Provided by: scons_2.1.0-1_all bug

NAME

       scons - a software construction tool

SYNOPSIS

       scons [ options...  ] [ name=val...  ] [ targets...  ]

DESCRIPTION

       The  scons  utility builds software (or other files) by determining which component pieces
       must be rebuilt and executing the necessary commands to rebuild them.

       By default, scons searches for a file named SConstruct, Sconstruct, or sconstruct (in that
       order) in the current directory and reads its configuration from the first file found.  An
       alternate file name may be specified via the -f option.

       The SConstruct file can specify subsidiary  configuration  files  using  the  SConscript()
       function.   By  convention, these subsidiary files are named SConscript, although any name
       may be used.  (Because of this naming convention, the term "SConscript files" is sometimes
       used  to  refer  generically  to  all scons configuration files, regardless of actual file
       name.)

       The configuration files specify the target files to be built, and (optionally)  the  rules
       to  build  those  targets.   Reasonable  default  rules exist for building common software
       components (executable programs, object files,  libraries),  so  that  for  most  software
       projects, only the target and input files need be specified.

       Before  reading  the  SConstruct  file,  scons  looks  for a directory named site_scons in
       various system directories (see below) and the directory containing the  SConstruct  file;
       for  each  of  those  dirs  which  exists,  site_scons  is prepended to sys.path, the file
       site_scons/site_init.py,   is   evaluated   if    it    exists,    and    the    directory
       site_scons/site_tools  is  prepended  to the default toolpath if it exists.  See the --no-
       site-dir and --site-dir options for more details.

       scons reads and executes the SConscript files as Python scripts, so  you  may  use  normal
       Python  scripting  capabilities  (such  as  flow  control, data manipulation, and imported
       Python libraries) to handle complicated  build  situations.   scons,  however,  reads  and
       executes  all of the SConscript files before it begins building any targets.  To make this
       obvious, scons prints the following messages about what it is doing:

              $ scons foo.out
              scons: Reading SConscript files ...
              scons: done reading SConscript files.
              scons: Building targets  ...
              cp foo.in foo.out
              scons: done building targets.
              $

       The status messages (everything except the line that reads "cp  foo.in  foo.out")  may  be
       suppressed using the -Q option.

       scons  does  not automatically propagate the external environment used to execute scons to
       the commands used to build target files.  This  is  so  that  builds  will  be  guaranteed
       repeatable regardless of the environment variables set at the time scons is invoked.  This
       also means that if the compiler or other commands that you  want  to  use  to  build  your
       target  files  are  not  in standard system locations, scons will not find them unless you
       explicitly set the PATH  to  include  those  locations.   Whenever  you  create  an  scons
       construction  environment,  you  can  propagate  the  value  of  PATH  from  your external
       environment as follows:

              import os
              env = Environment(ENV = {'PATH' : os.environ['PATH']})

       Similarly,  if  the  commands  use  external  environment  variables  like  $PATH,  $HOME,
       $JAVA_HOME, $LANG, $SHELL, $TERM, etc., these variables can also be explicitly propagated:

              import os
              env = Environment(ENV = {'PATH' : os.environ['PATH'],
                                       'HOME' : os.environ['HOME']})

       Or you may explicitly propagate the invoking user's complete external environment:

              import os
              env = Environment(ENV = os.environ)

       This  comes  at the expense of making your build dependent on the user's environment being
       set correctly, but it may be more convenient for many configurations.

       scons can scan known input files automatically for dependency  information  (for  example,
       #include  statements  in  C  or  C++ files) and will rebuild dependent files appropriately
       whenever any "included" input file changes.  scons supports  the  ability  to  define  new
       scanners for unknown input file types.

       scons  knows  how to fetch files automatically from SCCS or RCS subdirectories using SCCS,
       RCS or BitKeeper.

       scons is normally  executed  in  a  top-level  directory  containing  a  SConstruct  file,
       optionally specifying as command-line arguments the target file or files to be built.

       By default, the command

              scons

       will  build  all target files in or below the current directory.  Explicit default targets
       (to be built when no targets are specified  on  the  command  line)  may  be  defined  the
       SConscript file(s) using the Default() function, described below.

       Even  when  Default() targets are specified in the SConscript file(s), all target files in
       or below the current directory may be built by explicitly specifying the current directory
       (.)  as a command-line target:

              scons .

       Building  all  target  files, including any files outside of the current directory, may be
       specified by supplying a command-line target of the root directory (on POSIX systems):

              scons /

       or the path name(s) of the volume(s) in which all the targets should be built (on  Windows
       systems):

              scons C:\ D:\

       To build only specific targets, supply them as command-line arguments:

              scons foo bar

       in  which  case  only the specified targets will be built (along with any derived files on
       which they depend).

       Specifying "cleanup" targets in SConscript files is not usually necessary.   The  -c  flag
       removes all files necessary to build the specified target:

              scons -c .

       to remove all target files, or:

              scons -c build export

       to  remove target files under build and export.  Additional files or directories to remove
       can be specified using the Clean() function.  Conversely, targets that would  normally  be
       removed  by  the  -c invocation can be prevented from being removed by using the NoClean()
       function.

       A subset of a hierarchical tree may be built  by  remaining  at  the  top-level  directory
       (where  the  SConstruct  file  lives)  and specifying the subdirectory as the target to be
       built:

              scons src/subdir

       or by changing directory and invoking scons with the -u option,  which  traverses  up  the
       directory hierarchy until it finds the SConstruct file, and then builds targets relatively
       to the current subdirectory:

              cd src/subdir
              scons -u .

       scons supports building multiple targets in parallel via a -j option that  takes,  as  its
       argument, the number of simultaneous tasks that may be spawned:

              scons -j 4

       builds four targets in parallel, for example.

       scons  can  maintain a cache of target (derived) files that can be shared between multiple
       builds.  When caching is enabled in a SConscript file, any target  files  built  by  scons
       will  be copied to the cache.  If an up-to-date target file is found in the cache, it will
       be retrieved from the cache instead of being rebuilt locally.   Caching  behavior  may  be
       disabled  and controlled in other ways by the --cache-force, --cache-disable, and --cache-
       show command-line options.  The --random option is useful to prevent multiple builds  from
       trying to update the cache simultaneously.

       Values of variables to be passed to the SConscript file(s) may be specified on the command
       line:

              scons debug=1 .

       These variables are available in SConscript files through the  ARGUMENTS  dictionary,  and
       can be used in the SConscript file(s) to modify the build in any way:

              if ARGUMENTS.get('debug', 0):
                  env = Environment(CCFLAGS = '-g')
              else:
                  env = Environment()

       The  command-line  variable  arguments  are also available in the ARGLIST list, indexed by
       their order on the command line.  This allows you to process them in order rather than  by
       name,  if necessary.  ARGLIST[0] returns a tuple containing (argname, argvalue).  A Python
       exception is thrown if you try to access a list member that does not exist.

       scons requires Python version 2.4 or later.  There should  be  no  other  dependencies  or
       requirements to run scons.

       By  default, scons knows how to search for available programming tools on various systems.
       On Windows systems, scons searches in order for the Microsoft Visual C++ tools, the  MinGW
       tool  chain,  the  Intel  compiler  tools, and the PharLap ETS compiler.  On OS/2 systems,
       scons searches in order for the OS/2 compiler, the  GCC  tool  chain,  and  the  Microsoft
       Visual  C++  tools,  On SGI IRIX, IBM AIX, Hewlett Packard HP-UX, and Sun Solaris systems,
       scons searches for the native compiler tools (MIPSpro, Visual Age, aCC,  and  Forte  tools
       respectively)  and the GCC tool chain.  On all other platforms, including POSIX (Linux and
       UNIX) platforms, scons searches in order for the GCC tool chain, the Microsoft Visual  C++
       tools, and the Intel compiler tools.  You may, of course, override these default values by
       appropriate configuration of Environment construction variables.

OPTIONS

       In general, scons supports the same command-line options as GNU make, and  many  of  those
       supported by cons.

       -b     Ignored for compatibility with non-GNU versions of make.

       -c, --clean, --remove
              Clean  up  by  removing  all  target  files  for  which  a  construction command is
              specified.  Also remove any files or directories  associated  to  the  construction
              command  using  the Clean() function.  Will not remove any targets specified by the
              NoClean() function.

       --cache-debug=file
              Print debug information about the CacheDir() derived-file caching to the  specified
              file.   If  file is - (a hyphen), the debug information are printed to the standard
              output.  The printed messages describe what signature file names are  being  looked
              for in, retrieved from, or written to the CacheDir() directory tree.

       --cache-disable, --no-cache
              Disable  the  derived-file  caching  specified  by  CacheDir().  scons will neither
              retrieve files from the cache nor copy files to the cache.

       --cache-force, --cache-populate
              When using CacheDir(), populate a cache by copying any already-existing, up-to-date
              derived files to the cache, in addition to files built by this invocation.  This is
              useful to populate a new cache with all the current derived files, or to add to the
              cache  any  derived  files  recently  built  with caching disabled via the --cache-
              disable option.

       --cache-show
              When using CacheDir() and retrieving a  derived  file  from  the  cache,  show  the
              command  that  would  have  been  executed  to build the file, instead of the usual
              report, "Retrieved `file' from cache."  This will  produce  consistent  output  for
              build  logs,  regardless of whether a target file was rebuilt or retrieved from the
              cache.

       --config=mode
              This specifies how the Configure  call  should  use  or  generate  the  results  of
              configuration  tests.   The  option  should  be  specified from among the following
              choices:

       --config=auto
              scons will use its normal dependency mechanisms to decide if a test must be rebuilt
              or not.  This saves time by not running the same configuration tests every time you
              invoke scons, but will overlook changes in system header files or external commands
              (such as compilers) if you don't specify those dependecies explicitly.  This is the
              default behavior.

       --config=force
              If this option is specified, all configuration tests will be re-run  regardless  of
              whether  the  cached results are out of date.  This can be used to explicitly force
              the configuration tests to be updated in  response  to  an  otherwise  unconfigured
              change in a system header file or compiler.

       --config=cache
              If  this  option is specified, no configuration tests will be rerun and all results
              will be taken from cache.  Note that scons will  still  consider  it  an  error  if
              --config=cache  is  specified and a necessary test does not yet have any results in
              the cache.

       -C directory,  --directory=directory
              Change to the specified directory before searching for the SConstruct,  Sconstruct,
              or  sconstruct  file,  or doing anything else.  Multiple -C options are interpreted
              relative to the previous one, and the right-most -C option wins.  (This  option  is
              nearly  equivalent  to  -f  directory/SConstruct,  except  that  it will search for
              SConstruct, Sconstruct, or sconstruct in the specified directory.)

       -D     Works exactly the same way as the -u option except for the way default targets  are
              handled.   When  this  option  is  used and no targets are specified on the command
              line, all default targets are built, whether or not  they  are  below  the  current
              directory.

       --debug=type
              Debug the build process.  type specifies what type of debugging:

       --debug=count
              Print  how many objects are created of the various classes used internally by SCons
              before and after reading  the  SConscript  files  and  before  and  after  building
              targets.   This  is  not  supported  when  SCons  is  executed  with  the Python -O
              (optimized) option or when the SCons modules have been compiled  with  optimization
              (that is, when executing from *.pyo files).

       --debug=duplicate
              Print  a  line  for  each unlink/relink (or copy) of a variant file from its source
              file.  Includes debugging info for  unlinking  stale  variant  files,  as  well  as
              unlinking old targets before building them.

       --debug=dtree
              A  synonym  for  the  newer --tree=derived option.  This will be deprecated in some
              future release and ultimately removed.

       --debug=explain
              Print an explanation of precisely why scons is deciding to (re-)build any  targets.
              (Note:  this does not print anything for targets that are not rebuilt.)

       --debug=findlibs
              Instruct  the  scanner  that  searches  for libraries to print a message about each
              potential library name it is searching for,  and  about  the  actual  libraries  it
              finds.

       --debug=includes
              Print  the  include  tree  after each top-level target is built.  This is generally
              used to find out what files are included by the sources of a given derived file:

              $ scons --debug=includes foo.o

       --debug=memoizer
              Prints a summary of hits and misses using the Memoizer, an internal subsystem  that
              counts  how  often  SCons  uses cached values in memory instead of recomputing them
              each time they're needed.

       --debug=memory
              Prints how much memory SCons uses before and after reading the SConscript files and
              before and after building targets.

       --debug=nomemoizer
              A deprecated option preserved for backwards compatibility.

       --debug=objects
              Prints  a  list  of  the  various objects of the various classes used internally by
              SCons.

       --debug=pdb
              Re-run SCons under the control of the pdb Python debugger.

       --debug=prepare
              Print a line each time any target (internal or external) is prepared for  building.
              scons  prints  this for each target it considers, even if that target is up to date
              (see also --debug=explain).  This can help debug problems with targets that  aren't
              being built; it shows whether scons is at least considering them or not.

       --debug=presub
              Print  the  raw  command  line  used  to  build each target before the construction
              environment variables are substituted.  Also shows which targets are being built by
              this command.  Output looks something like this:
              $ scons --debug=presub
              Building myprog.o with action(s):
                $SHCC $SHCFLAGS $SHCCFLAGS $CPPFLAGS $_CPPINCFLAGS -c -o $TARGET $SOURCES
              ...

       --debug=stacktrace
              Prints  an  internal  Python stack trace when encountering an otherwise unexplained
              error.

       --debug=stree
              A synonym for the newer --tree=all,status option.  This will be deprecated in  some
              future release and ultimately removed.

       --debug=time
              Prints various time profiling information: the time spent executing each individual
              build command; the total build time (time SCons ran from  beginning  to  end);  the
              total time spent reading and executing SConscript files; the total time spent SCons
              itself spend running (that  is,  not  counting  reading  and  executing  SConscript
              files);  and both the total time spent executing all build commands and the elapsed
              wall-clock time spent executing those build  commands.   (When  scons  is  executed
              without  the  -j  option,  the  elapsed  wall-clock time will typically be slightly
              longer than the total time spent executing all the build commands, due to the SCons
              processing  that  takes  place  in  between  executing each command.  When scons is
              executed  with  the  -j  option,  and  your   build   configuration   allows   good
              parallelization,  the  elapsed wall-clock time should be significantly smaller than
              the total time spent  executing  all  the  build  commands,  since  multiple  build
              commands and intervening SCons processing should take place in parallel.)

       --debug=tree
              A  synonym for the newer --tree=all option.  This will be deprecated in some future
              release and ultimately removed.

       --diskcheck=types
              Enable specific checks for whether or not there is a file on disk where  the  SCons
              configuration  expects  a directory (or vice versa), and whether or not RCS or SCCS
              sources exist when searching for source and include files.  The types argument  can
              be  set  to:  all, to enable all checks explicitly (the default behavior); none, to
              disable all such checks; match, to check that files and directories on  disk  match
              SCons' expected configuration; rcs, to check for the existence of an RCS source for
              any missing source or include files; sccs, to check for the existence  of  an  SCCS
              source  for  any missing source or include files.  Multiple checks can be specified
              separated by commas; for example, --diskcheck=sccs,rcs would still check  for  SCCS
              and  RCS  sources,  but  disable  the  check  for  on-disk  matches  of  files  and
              directories.  Disabling some or all of these checks can provide a performance boost
              for  large  configurations,  or  when the configuration will check for files and/or
              directories across networked or shared file systems, at the slight  increased  risk
              of an incorrect build or of not handling errors gracefully (if include files really
              should be found in SCCS or RCS, for example, or if a file really does  exist  where
              the SCons configuration expects a directory).

       --duplicate=ORDER
              There  are  three  ways  to  duplicate  files  in  a  build  tree: hard links, soft
              (symbolic) links and copies. The default behaviour of SCons is to prefer hard links
              to  soft  links  to  copies. You can specify different behaviours with this option.
              ORDER must be one of hard-soft-copy (the default), soft-hard-copy, hard-copy, soft-
              copy  or  copy.   SCons will attempt to duplicate files using the mechanisms in the
              specified order.

       -f file, --file=file, --makefile=file, --sconstruct=file
              Use file as the initial SConscript file.  Multiple -f options may be specified,  in
              which case scons will read all of the specified files.

       -h, --help
              Print  a  local  help  message  for this build, if one is defined in the SConscript
              file(s), plus a line that describes the -H option for command-line option help.  If
              no  local  help message is defined, prints the standard help message about command-
              line options.  Exits after displaying the appropriate message.

       -H, --help-options
              Print the standard help message about command-line options and exit.

       -i, --ignore-errors
              Ignore all errors from commands executed to rebuild files.

       -I directory, --include-dir=directory
              Specifies a directory to search for imported Python modules.  If several -I options
              are used, the directories are searched in the order specified.

       --implicit-cache
              Cache  implicit  dependencies.   This  causes  scons  to use the implicit (scanned)
              dependencies from the last time it was  run  instead  of  scanning  the  files  for
              implicit  dependencies.   This  can  significantly  speed  up  SCons,  but with the
              following limitations:

              scons will not detect changes to implicit dependency search paths  (e.g.   CPPPATH,
              LIBPATH)  that  would ordinarily cause different versions of same-named files to be
              used.

              scons will miss changes in the implicit dependencies in cases where a new  implicit
              dependency  is added earlier in the implicit dependency search path (e.g.  CPPPATH,
              LIBPATH) than a current implicit dependency with the same name.

       --implicit-deps-changed
              Forces SCons to ignore the cached implicit dependencies. This causes  the  implicit
              dependencies to be rescanned and recached. This implies --implicit-cache.

       --implicit-deps-unchanged
              Force  SCons  to  ignore  changes in the implicit dependencies.  This causes cached
              implicit dependencies to always be used.  This implies --implicit-cache.

       --interactive
              Starts SCons in interactive mode.   The  SConscript  files  are  read  once  and  a
              scons>>>  prompt  is  printed.   Targets  may  now be rebuilt by typing commands at
              interactive prompt without having to re-read the SConscript files and re-initialize
              the dependency graph from scratch.

              SCons interactive mode supports the following commands:

                 build[OPTIONS] [TARGETS] ...
                       Builds  the  specified TARGETS (and their dependencies) with the specified
                       SCons command-line OPTIONS.  b and scons are synonyms.

                       The following SCons command-line options affect the build command:

                       --cache-debug=FILE
                       --cache-disable, --no-cache
                       --cache-force, --cache-populate
                       --cache-show
                       --debug=TYPE
                       -i, --ignore-errors
                       -j N, --jobs=N
                       -k, --keep-going
                       -n, --no-exec, --just-print, --dry-run, --recon
                       -Q
                       -s, --silent, --quiet
                       --taskmastertrace=FILE
                       --tree=OPTIONS

                       Any other SCons command-line options  that  are  specified  do  not  cause
                       errors but have no effect on the build command (mainly because they affect
                       how the SConscript  files  are  read,  which  only  happens  once  at  the
                       beginning of interactive mode).

                 clean[OPTIONS] [TARGETS] ...
                       Cleans  the  specified TARGETS (and their dependencies) with the specified
                       options.  c is a synonym.  This command is  itself  a  synonym  for  build
                       --clean

                 exit  Exits  SCons  interactive  mode.   You  can also exit by terminating input
                       (CTRL+D on UNIX or Linux systems, CTRL+Z on Windows systems).

                 help[COMMAND]
                       Provides a help message about the commands available in SCons  interactive
                       mode.  If COMMAND is specified, h and ?  are synonyms.

                 shell[COMMANDLINE]
                       Executes  the  specified  COMMANDLINE in a subshell.  If no COMMANDLINE is
                       specified, executes the interactive command interpreter specified  in  the
                       SHELL  environment  variable  (on  UNIX  and Linux systems) or the COMSPEC
                       environment variable (on Windows systems).  sh and !  are synonyms.

                 version
                       Prints SCons version information.

              An empty line repeats the last typed command.  Command-line editing can be used  if
              the readline module is available.

              $ scons --interactive
              scons: Reading SConscript files ...
              scons: done reading SConscript files.
              scons>>> build -n prog
              scons>>> exit

       -j N, --jobs=N
              Specifies  the  number  of jobs (commands) to run simultaneously.  If there is more
              than one -j option, the last one is effective.

       -k, --keep-going
              Continue as much as possible after an error.  The target that failed and those that
              depend  on  it  will not be remade, but other targets specified on the command line
              will still be processed.

       -m     Ignored for compatibility with non-GNU versions of make.

       --max-drift=SECONDS
              Set the maximum expected drift in the modification time of files to SECONDS.   This
              value  determines  how  long  a  file  must be unmodified before its cached content
              signature will be  used  instead  of  calculating  a  new  content  signature  (MD5
              checksum)  of the file's contents.  The default value is 2 days, which means a file
              must have a modification time of at least two days ago in order to have its  cached
              content  signature  used.   A  negative  value  means  to  never  cache the content
              signature and to ignore the cached value if there already is  one.  A  value  of  0
              means to always use the cached signature, no matter how old the file is.

       --md5-chunksize=KILOBYTES
              Set  the  block  size  used  to  compute  MD5  signatures to KILOBYTES.  This value
              determines the size of the chunks which are read in  at  once  when  computing  MD5
              signatures.  Files below that size are fully stored in memory before performing the
              signature computation while bigger files are read in block-by-block. A huge  block-
              size  leads to high memory consumption while a very small block-size slows down the
              build considerably.

              The default value is to  use  a  chunk  size  of  64  kilobytes,  which  should  be
              appropriate for most uses.

       -n, --just-print, --dry-run, --recon
              No  execute.   Print  the  commands that would be executed to build any out-of-date
              target files, but do not execute the commands.

       --no-site-dir
              Prevents the automatic addition of the standard site_scons dirs to sys.path.   Also
              prevents  loading  the  site_scons/site_init.py modules if they exist, and prevents
              adding their site_scons/site_tools dirs to the toolpath.

       --profile=file
              Run SCons under the Python profiler and save the results  in  the  specified  file.
              The results may be analyzed using the Python pstats module.

       -q, --question
              Do  not  run  any  commands, or print anything.  Just return an exit status that is
              zero if the specified targets are already up to date, non-zero otherwise.

       -Q     Quiets SCons status messages about reading SConscript files, building  targets  and
              entering directories.  Commands that are executed to rebuild target files are still
              printed.

       --random
              Build dependencies in a random order.  This is useful when building multiple  trees
              simultaneously with caching enabled, to prevent multiple builds from simultaneously
              trying to build or retrieve the same target files.

       -s, --silent, --quiet
              Silent.  Do not print commands that are executed to  rebuild  target  files.   Also
              suppresses SCons status messages.

       -S, --no-keep-going, --stop
              Ignored for compatibility with GNU make.

       --site-dir=dir
              Uses  the  named dir as the site dir rather than the default site_scons dirs.  This
              dir will get prepended to sys.path, the module dir/site_init.py will get loaded  if
              it exists, and dir/site_tools will get added to the default toolpath.

              The default set of site_scons dirs used when --site-dir is not specified depends on
              the system platform, as follows.  Note that the directories  are  examined  in  the
              order  given, from most generic to most specific, so the last-executed site_init.py
              file is the most specific one (which gives it the  chance  to  override  everything
              else),  and  the  dirs  are  prepended to the paths, again so the last dir examined
              comes first in the resulting path.

       Windows:
                  %ALLUSERSPROFILE/Application Data/scons/site_scons
                  %USERPROFILE%/Local Settings/Application Data/scons/site_scons
                  %APPDATA%/scons/site_scons
                  %HOME%/.scons/site_scons
                  ./site_scons

       Mac OS X:
                  /Library/Application Support/SCons/site_scons
                  /opt/local/share/scons/site_scons (for MacPorts)
                  /sw/share/scons/site_scons (for Fink)
                  $HOME/Library/Application Support/SCons/site_scons
                  $HOME/.scons/site_scons
                  ./site_scons

       Solaris:
                  /opt/sfw/scons/site_scons
                  /usr/share/scons/site_scons
                  $HOME/.scons/site_scons
                  ./site_scons

       Linux, HPUX, and other Posix-like systems:
                  /usr/share/scons/site_scons
                  $HOME/.scons/site_scons
                  ./site_scons

       --stack-size=KILOBYTES
              Set the size stack used to run threads to KILOBYTES.   This  value  determines  the
              stack size of the threads used to run jobs.  These are the threads that execute the
              actions of the builders for the nodes that are out-of-date.  Note that this  option
              has  no  effect  unless the num_jobs option, which corresponds to -j and --jobs, is
              larger than one.  Using a stack size that is too small  may  cause  stack  overflow
              errors.   This  usually  shows  up as segmentation faults that cause scons to abort
              before building anything.  Using a stack size that is too large will cause scons to
              use more memory than required and may slow down the entire build process.

              The  default  value  is  to  use  a  stack  size  of 256 kilobytes, which should be
              appropriate for most uses.  You should not need to increase this value  unless  you
              encounter stack overflow errors.

       -t, --touch
              Ignored for compatibility with GNU make.  (Touching a file to make it appear up-to-
              date is unnecessary when using scons.)

       --taskmastertrace=file
              Prints trace information to the specified file about how  the  internal  Taskmaster
              object evaluates and controls the order in which Nodes are built.  A file name of -
              may be used to specify the standard output.

       -tree=options
              Prints a tree of the dependencies after  each  top-level  target  is  built.   This
              prints  out  some  or all of the tree, in various formats, depending on the options
              specified:

       --tree=all
              Print the entire dependency tree after each top-level target is built.  This prints
              out  the  complete  dependency  tree,  including  implicit dependencies and ignored
              dependencies.

       --tree=derived
              Restricts the tree output to only derived (target) files, not source files.

       --tree=status
              Prints status information for each displayed node.

       --tree=prune
              Prunes the tree to avoid repeating  dependency  information  for  nodes  that  have
              already  been  displayed.   Any  node that has already been displayed will have its
              name printed in [square brackets], as an indication that the dependencies for  that
              node can be found by searching for the relevant output higher up in the tree.

              Multiple options may be specified, separated by commas:

              # Prints only derived files, with status information:
              scons --tree=derived,status

              # Prints all dependencies of target, with status information
              # and pruning dependencies of already-visited Nodes:
              scons --tree=all,prune,status target

       -u, --up, --search-up
              Walks  up  the  directory  structure until an SConstruct , Sconstruct or sconstruct
              file is found, and uses that as the top of the directory tree.  If no  targets  are
              specified  on the command line, only targets at or below the current directory will
              be built.

       -U     Works exactly the same way as the -u option except for the way default targets  are
              handled.   When  this  option  is  used and no targets are specified on the command
              line, all default targets that are defined in  the  SConscript(s)  in  the  current
              directory are built, regardless of what directory the resultant targets end up in.

       -v, --version
              Print  the  scons  version,  copyright  information, list of authors, and any other
              relevant information.  Then exit.

       -w, --print-directory
              Print a message containing the working directory before and after other processing.

       --no-print-directory
              Turn off -w, even if it was turned on implicitly.

       --warn=type, --warn=no-type
              Enable or disable warnings.  type specifies the type of warnings to be  enabled  or
              disabled:

       --warn=all, --warn=no-all
              Enables or disables all warnings.

       --warn=cache-write-error, --warn=no-cache-write-error
              Enables or disables warnings about errors trying to write a copy of a built file to
              a specified CacheDir().  These warnings are disabled by default.

       --warn=corrupt-sconsign, --warn=no-corrupt-sconsign
              Enables or disables warnings about unfamiliar signature data  in  .sconsign  files.
              These warnings are enabled by default.

       --warn=dependency, --warn=no-dependency
              Enables  or  disables  warnings about dependencies.  These warnings are disabled by
              default.

       --warn=deprecated, --warn=no-deprecated
              Enables or disables all warnings about use of currently deprecated features.  These
              warnings  are  enabled  by default.  Note that the --warn=no-deprecated option does
              not disable warnings about absolutely all deprecated features.  Warnings  for  some
              deprecated   features   that  have  already  been  through  several  releases  with
              deprecation warnings may be  mandatory  for  a  release  or  two  before  they  are
              officially  no  longer  supported  by SCons.  Warnings for some specific deprecated
              features may be enabled or disabled individually; see below.

              --warn=deprecated-copy, --warn=no-deprecated-copy
                     Enables or disables warnings about use of the deprecated env.Copy() method.

              --warn=deprecated-source-signatures, --warn=no-deprecated-source-signatures
                     Enables or disables warnings about use of the deprecated  SourceSignatures()
                     function or env.SourceSignatures() method.

              --warn=deprecated-target-signatures, --warn=no-deprecated-target-signatures
                     Enables  or disables warnings about use of the deprecated TargetSignatures()
                     function or env.TargetSignatures() method.

       --warn=duplicate-environment, --warn=no-duplicate-environment
              Enables or disables warnings about attempts to specify a build of a target with two
              different  construction  environments that use the same action.  These warnings are
              enabled by default.

       --warn=fortran-cxx-mix, --warn=no-fortran-cxx-mix
              Enables or disables the specific warning about linking Fortran and C++ object files
              in a single executable, which can yield unpredictable behavior with some compilers.

       --warn=future-deprecated, --warn=no-future-deprecated
              Enables  or disables warnings about features that will be deprecated in the future.
              These warnings are disabled  by  default.   Enabling  this  warning  is  especially
              recommended  for projects that redistribute SCons configurations for other users to
              build, so that the project can be warned as soon as possible about to-be-deprecated
              features that may require changes to the configuration.

       --warn=link, --warn=no-link
              Enables or disables warnings about link steps.

       --warn=misleading-keywords, --warn=no-misleading-keywords
              Enables  or  disables  warnings  about  use  of the misspelled keywords targets and
              sources when calling Builders.  (Note the last s characters, the correct  spellings
              are target and source.)  These warnings are enabled by default.

       --warn=missing-sconscript, --warn=no-missing-sconscript
              Enables  or  disables  warnings about missing SConscript files.  These warnings are
              enabled by default.

       --warn=no-md5-module, --warn=no-no-md5-module
              Enables or disables warnings about the version of Python not having an MD5 checksum
              module available.  These warnings are enabled by default.

       --warn=no-metaclass-support, --warn=no-no-metaclass-support
              Enables or disables warnings about the version of Python not supporting metaclasses
              when the --debug=memoizer option is used.  These warnings are enabled by default.

       --warn=no-object-count, --warn=no-no-object-count
              Enables or disables warnings about the  --debug=object  feature  not  working  when
              scons is run with the python -O option or from optimized Python (.pyo) modules.

       --warn=no-parallel-support, --warn=no-no-parallel-support
              Enables  or disables warnings about the version of Python not being able to support
              parallel builds when the -j option is used.  These warnings are enabled by default.

       --warn=python-version, --warn=no-python-version
              Enables or disables the warning about running SCons with a  deprecated  version  of
              Python.  These warnings are enabled by default.

       --warn=reserved-variable, --warn=no-reserved-variable
              Enables  or  disables  warnings  about  attempts  to  set the reserved construction
              variable names CHANGED_SOURCES, CHANGED_TARGETS, TARGET, TARGETS, SOURCE,  SOURCES,
              UNCHANGED_SOURCES or UNCHANGED_TARGETS.  These warnings are disabled by default.

       --warn=stack-size, --warn=no-stack-size
              Enables or disables warnings about requests to set the stack size that could not be
              honored.  These warnings are enabled by default.

       -Y repository, --repository=repository, --srcdir=repository
              Search the specified repository for any input and target files  not  found  in  the
              local directory hierarchy.  Multiple -Y options may be specified, in which case the
              repositories are searched in the order specified.

CONFIGURATION FILE REFERENCE

   Construction Environments
       A construction environment is the basic means by which the  SConscript  files  communicate
       build  information  to  scons.   A  new  construction  environment  is  created  using the
       Environment function:

              env = Environment()

       Variables, called construction variables, may be set in a construction environment  either
       by  specifying  them  as  keywords when the object is created or by assigning them a value
       after the object is created:

              env = Environment(FOO = 'foo')
              env['BAR'] = 'bar'

       As a convenience, construction variables may also be set or modified  by  the  parse_flags
       keyword  argument,  which  applies the ParseFlags method (described below) to the argument
       value after all other processing is completed.  This is useful either if the exact content
       of  the  flags  is  unknown  (for  example,  read from a control file) or if the flags are
       distributed to a number of construction variables.

              env = Environment(parse_flags = '-Iinclude -DEBUG -lm')

       This example adds 'include' to CPPPATH, 'EBUG' to CPPDEFINES, and 'm' to LIBS.

       By default, a new construction environment is initialized with a set  of  builder  methods
       and  construction  variables  that  are appropriate for the current platform.  An optional
       platform keyword argument may be used to specify that an environment should be initialized
       for a different platform:

              env = Environment(platform = 'cygwin')
              env = Environment(platform = 'os2')
              env = Environment(platform = 'posix')
              env = Environment(platform = 'win32')

       Specifying   a   platform  initializes  the  appropriate  construction  variables  in  the
       environment to use and generate file names with prefixes and suffixes appropriate for  the
       platform.

       Note that the win32 platform adds the SystemDrive and SystemRoot variables from the user's
       external environment to the construction environment's ENV dictionary.  This  is  so  that
       any  executed  commands  that  use sockets to connect with other systems (such as fetching
       source     files     from     external     CVS     repository     specifications      like
       :pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons) will work on Windows systems.

       The  platform argument may be function or callable object, in which case the Environment()
       method will call the specified argument to update the new construction environment:

              def my_platform(env):
                  env['VAR'] = 'xyzzy'

              env = Environment(platform = my_platform)

       Additionally, a specific set of tools with which to  initialize  the  environment  may  be
       specified as an optional keyword argument:

              env = Environment(tools = ['msvc', 'lex'])

       Non-built-in tools may be specified using the toolpath argument:

              env = Environment(tools = ['default', 'foo'], toolpath = ['tools'])

       This looks for a tool specification in tools/foo.py (as well as using the ordinary default
       tools for the platform).  foo.py  should  have  two  functions:  generate(env,  **kw)  and
       exists(env).   The  generate()  function  modifies  the  passed-in  environment  to set up
       variables so that the tool can be executed; it may use any keyword arguments that the user
       supplies  (see  below)  to vary its initialization.  The exists() function should return a
       true value if the tool is available.  Tools in the toolpath are used  before  any  of  the
       built-in ones.  For example, adding gcc.py to the toolpath would override the built-in gcc
       tool.  Also note that the toolpath is stored in the environment for use by later calls  to
       Clone() and Tool() methods:

              base = Environment(toolpath=['custom_path'])
              derived = base.Clone(tools=['custom_tool'])
              derived.CustomBuilder()

       The  elements  of  the tools list may also be functions or callable objects, in which case
       the Environment() method will call the specified elements to update the  new  construction
       environment:

              def my_tool(env):
                  env['XYZZY'] = 'xyzzy'

              env = Environment(tools = [my_tool])

       The  individual elements of the tools list may also themselves be two-element lists of the
       form (toolname, kw_dict).  SCons searches for the toolname specification file as described
       above,  and passes kw_dict, which must be a dictionary, as keyword arguments to the tool's
       generate function.  The generate function can use  the  arguments  to  modify  the  tool's
       behavior  by  setting  up  the  environment  in  different  ways or otherwise changing its
       initialization.

              # in tools/my_tool.py:
              def generate(env, **kw):
                # Sets MY_TOOL to the value of keyword argument 'arg1' or 1.
                env['MY_TOOL'] = kw.get('arg1', '1')
              def exists(env):
                return 1

              # in SConstruct:
              env = Environment(tools = ['default', ('my_tool', {'arg1': 'abc'})],
                                toolpath=['tools'])

       The tool definition (i.e. my_tool()) can use the PLATFORM variable from the environment it
       receives to customize the tool for different platforms.

       If  no  tool  list is specified, then SCons will auto-detect the installed tools using the
       PATH variable in the ENV construction variable and the platform name when the  Environment
       is  constructed.  Changing the PATH variable after the Environment is constructed will not
       cause the tools to be redetected.

       SCons supports the following tool specifications out of the box:

              386asm
              aixc++
              aixcc
              aixf77
              aixlink
              ar
              as
              bcc32
              c++
              cc
              cvf
              dmd
              dvipdf
              dvips
              f77
              f90
              f95
              fortran
              g++
              g77
              gas
              gcc
              gfortran
              gnulink
              gs
              hpc++
              hpcc
              hplink
              icc
              icl
              ifl
              ifort
              ilink
              ilink32
              intelc
              jar
              javac
              javah
              latex
              lex
              link
              linkloc
              m4
              masm
              midl
              mingw
              mslib
              mslink
              mssdk
              msvc
              msvs
              mwcc
              mwld
              nasm
              pdflatex
              pdftex
              qt
              rmic
              rpcgen
              sgiar
              sgic++
              sgicc
              sgilink
              sunar
              sunc++
              suncc
              sunf77
              sunf90
              sunf95
              sunlink
              swig
              tar
              tex
              textfile
              tlib
              yacc
              zip

       Additionally, there is a "tool" named default which  configures  the  environment  with  a
       default set of tools for the current platform.

       On  posix and cygwin platforms the GNU tools (e.g. gcc) are preferred by SCons, on Windows
       the Microsoft tools (e.g. msvc) followed by MinGW are preferred by SCons, and in OS/2  the
       IBM tools (e.g. icc) are preferred by SCons.

   Builder Methods
       Build  rules  are  specified by calling a construction environment's builder methods.  The
       arguments to the builder methods are target (a list of targets to be built,  usually  file
       names) and source (a list of sources to be built, usually file names).

       Because  long  lists  of file names can lead to a lot of quoting, scons supplies a Split()
       global function and a same-named environment method that split  a  single  string  into  a
       list,  separated  on strings of white-space characters.  (These are similar to the split()
       member function of Python strings but work even if the input isn't a string.)

       Like all Python arguments, the target and source arguments to  a  builder  method  can  be
       specified  either  with  or without the "target" and "source" keywords.  When the keywords
       are omitted, the target is first, followed by the source.  The  following  are  equivalent
       examples of calling the Program builder method:

              env.Program('bar', ['bar.c', 'foo.c'])
              env.Program('bar', Split('bar.c foo.c'))
              env.Program('bar', env.Split('bar.c foo.c'))
              env.Program(source =  ['bar.c', 'foo.c'], target = 'bar')
              env.Program(target = 'bar', Split('bar.c foo.c'))
              env.Program(target = 'bar', env.Split('bar.c foo.c'))
              env.Program('bar', source = 'bar.c foo.c'.split())

       Target  and source file names that are not absolute path names (that is, do not begin with
       / on POSIX systems or  on Windows systems, with or without an optional drive  letter)  are
       interpreted  relative  to  the  directory  containing  the SConscript file being read.  An
       initial # (hash mark) on a path name means that the rest of the file name  is  interpreted
       relative  to  the  directory  containing  the  top-level SConstruct file, even if the # is
       followed by a directory separator character (slash or backslash).

       Examples:

              # The comments describing the targets that will be built
              # assume these calls are in a SConscript file in the
              # a subdirectory named "subdir".

              # Builds the program "subdir/foo" from "subdir/foo.c":
              env.Program('foo', 'foo.c')

              # Builds the program "/tmp/bar" from "subdir/bar.c":
              env.Program('/tmp/bar', 'bar.c')

              # An initial '#' or '#/' are equivalent; the following
              # calls build the programs "foo" and "bar" (in the
              # top-level SConstruct directory) from "subdir/foo.c" and
              # "subdir/bar.c", respectively:
              env.Program('#foo', 'foo.c')
              env.Program('#/bar', 'bar.c')

              # Builds the program "other/foo" (relative to the top-level
              # SConstruct directory) from "subdir/foo.c":
              env.Program('#other/foo', 'foo.c')

       When the target shares the same base name as the source and only the suffix varies, and if
       the builder method has a suffix defined for the target file type, then the target argument
       may be omitted completely, and scons will deduce the target file name from the source file
       name.   The  following examples all build the executable program bar (on POSIX systems) or
       bar.exe (on Windows systems) from the bar.c source file:

              env.Program(target = 'bar', source = 'bar.c')
              env.Program('bar', source = 'bar.c')
              env.Program(source = 'bar.c')
              env.Program('bar.c')

       As a convenience, a srcdir keyword argument may be specified when calling a Builder.  When
       specified,  all  source  file  strings  that  are  not  absolute paths will be interpreted
       relative to the specified srcdir.  The following example will  build  the  build/prog  (or
       build/prog.exe on Windows) program from the files src/f1.c and src/f2.c:

              env.Program('build/prog', ['f1.c', 'f2.c'], srcdir='src')

       It  is possible to override or add construction variables when calling a builder method by
       passing additional keyword arguments.  These overridden or added variables will only be in
       effect  when  building  the  target, so they will not affect other parts of the build. For
       example, if you want to add additional libraries for just one program:

              env.Program('hello', 'hello.c', LIBS=['gl', 'glut'])

       or generate a shared library with a non-standard suffix:

              env.SharedLibrary('word', 'word.cpp',
                                SHLIBSUFFIX='.ocx',
                                LIBSUFFIXES=['.ocx'])

       (Note that both the $SHLIBSUFFIX and $LIBSUFFIXES variables must be set if you want  SCons
       to  search  automatically  for  dependencies  on  the  non-standard library names; see the
       descriptions of these variables, below, for more information.)

       It is also possible to use the parse_flags keyword argument in an override:

              env = Program('hello', 'hello.c', parse_flags = '-Iinclude -DEBUG -lm')

       This example adds 'include' to CPPPATH, 'EBUG' to CPPDEFINES, and 'm' to LIBS.

       Although the builder methods defined by scons are, in  fact,  methods  of  a  construction
       environment object, they may also be called without an explicit environment:

              Program('hello', 'hello.c')
              SharedLibrary('word', 'word.cpp')

       In  this  case, the methods are called internally using a default construction environment
       that consists of the tools and values that scons has determined are  appropriate  for  the
       local system.

       Builder  methods  that  can  be  called without an explicit environment may be called from
       custom Python modules that you import into an SConscript file by adding the  following  to
       the Python module:

              from SCons.Script import *

       All  builder  methods return a list-like object containing Nodes that represent the target
       or targets that will be built.  A Node is an internal SCons object which represents  build
       targets or sources.

       The  returned  Node-list  object  can  be  passed to other builder methods as source(s) or
       passed to any SCons function or method where a filename would normally be  accepted.   For
       example, if it were necessary to add a specific -D flag when compiling one specific object
       file:

              bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
              env.Program(source = ['foo.c', bar_obj_list, 'main.c'])

       Using a Node in this way makes for a more portable build by avoiding having to  specify  a
       platform-specific object suffix when calling the Program() builder method.

       Note  that Builder calls will automatically "flatten" the source and target file lists, so
       it's all right to have the bar_obj list return by the StaticObject() call in the middle of
       the  source  file  list.   If  you need to manipulate a list of lists returned by Builders
       directly using Python, you can either build the list by hand:

              foo = Object('foo.c')
              bar = Object('bar.c')
              objects = ['begin.o'] + foo + ['middle.o'] + bar + ['end.o']
              for object in objects:
                  print str(object)

       Or you can use the Flatten() function supplied by scons to create a list  containing  just
       the Nodes, which may be more convenient:

              foo = Object('foo.c')
              bar = Object('bar.c')
              objects = Flatten(['begin.o', foo, 'middle.o', bar, 'end.o'])
              for object in objects:
                  print str(object)

       Note also that because Builder calls return a list-like object, not an actual Python list,
       you should not use the Python += operator to append Builder  results  to  a  Python  list.
       Because  the  list and the object are different types, Python will not update the original
       list in place, but will instead create a new Node-list object containing the concatenation
       of  the  list  elements  and  the Builder results.  This will cause problems for any other
       Python variables in your SCons configuration that still hold on  to  a  reference  to  the
       original  list.  Instead, use the Python .extend() method to make sure the list is updated
       in-place.  Example:

              object_files = []

              # Do NOT use += as follows:
              #
              #    object_files += Object('bar.c')
              #
              # It will not update the object_files list in place.
              #
              # Instead, use the .extend() method:
              object_files.extend(Object('bar.c'))

       The path name for a Node's file may be used by passing  the  Node  to  the  Python-builtin
       str() function:

              bar_obj_list = env.StaticObject('bar.c', CPPDEFINES='-DBAR')
              print "The path to bar_obj is:", str(bar_obj_list[0])

       Note  again  that  because  the  Builder  call returns a list, we have to access the first
       element in the list (bar_obj_list[0]) to get at the  Node  that  actually  represents  the
       object file.

       Builder calls support a chdir keyword argument that specifies that the Builder's action(s)
       should be executed after changing directory.  If the chdir  argument  is  a  string  or  a
       directory  Node,  scons  will  change  to  the specified directory.  If the chdir is not a
       string or Node and is non-zero, then scons will change to the target file's directory.

              # scons will change to the "sub" subdirectory
              # before executing the "cp" command.
              env.Command('sub/dir/foo.out', 'sub/dir/foo.in',
                          "cp dir/foo.in dir/foo.out",
                          chdir='sub')

              # Because chdir is not a string, scons will change to the
              # target's directory ("sub/dir") before executing the
              # "cp" command.
              env.Command('sub/dir/foo.out', 'sub/dir/foo.in',
                          "cp foo.in foo.out",
                          chdir=1)

       Note that scons will not automatically modify its expansion of construction variables like
       $TARGET  and  $SOURCE  when  using  the chdir keyword argument--that is, the expanded file
       names will still be relative to  the  top-level  SConstruct  directory,  and  consequently
       incorrect  relative  to  the  chdir directory.  If you use the chdir keyword argument, you
       will  typically  need  to  supply  a  different  command  line   using   expansions   like
       ${TARGET.file}  and  ${SOURCE.file}  to  use  just the filename portion of the targets and
       source.

       scons provides the following builder methods:

       CFile()

       env.CFile()
              Builds a C source file given a lex (.l)  or  yacc  (.y)  input  file.   The  suffix
              specified   by   the   $CFILESUFFIX   construction  variable  (.c  by  default)  is
              automatically added to the target if it is not already present.  Example:

              # builds foo.c
              env.CFile(target = 'foo.c', source = 'foo.l')
              # builds bar.c
              env.CFile(target = 'bar', source = 'bar.y')

       Command()

       env.Command()
              The Command() "Builder" is actually implemented as a function  that  looks  like  a
              Builder,  but  actually  takes  an additional argument of the action from which the
              Builder should be made.  See the Command() function  description  for  the  calling
              syntax and details.

       CXXFile()

       env.CXXFile()
              Builds  a  C++  source file given a lex (.ll) or yacc (.yy) input file.  The suffix
              specified  by  the  $CXXFILESUFFIX  construction  variable  (.cc  by  default)   is
              automatically added to the target if it is not already present.  Example:

              # builds foo.cc
              env.CXXFile(target = 'foo.cc', source = 'foo.ll')
              # builds bar.cc
              env.CXXFile(target = 'bar', source = 'bar.yy')

       DVI()

       env.DVI()
              Builds  a  .dvi  file  from  a .tex, .ltx or .latex input file.  If the source file
              suffix is .tex, scons will  examine  the  contents  of  the  file;  if  the  string
              ocumentclass  or  ocumentstyle is found, the file is assumed to be a LaTeX file and
              the target is built by invoking the $LATEXCOM command line; otherwise, the  $TEXCOM
              command  line  is used.  If the file is a LaTeX file, the DVI() builder method will
              also examine the contents of the .aux file and invoke the $BIBTEX command  line  if
              the  string  bibdata is found, start $MAKEINDEX to generate an index if a .ind file
              is found and will examine the contents .log file and re-run the  $LATEXCOM  command
              if the log file says it is necessary.

              The suffix .dvi (hard-coded within TeX itself) is automatically added to the target
              if it is not already present.  Examples:

              # builds from aaa.tex
              env.DVI(target = 'aaa.dvi', source = 'aaa.tex')
              # builds bbb.dvi
              env.DVI(target = 'bbb', source = 'bbb.ltx')
              # builds from ccc.latex
              env.DVI(target = 'ccc.dvi', source = 'ccc.latex')

       Install()

       env.Install()
              Installs one or more source files or directories in  the  specified  target,  which
              must be a directory.  The names of the specified source files or directories remain
              the same within the destination directory.

              env.Install('/usr/local/bin', source = ['foo', 'bar'])

       InstallAs()

       env.InstallAs()
              Installs one or more source  files  or  directories  to  specific  names,  allowing
              changing  a  file or directory name as part of the installation.  It is an error if
              the target and source arguments list different numbers of files or directories.

              env.InstallAs(target = '/usr/local/bin/foo',
                            source = 'foo_debug')
              env.InstallAs(target = ['../lib/libfoo.a', '../lib/libbar.a'],
                            source = ['libFOO.a', 'libBAR.a'])

       Jar()

       env.Jar()
              Builds a Java archive  (.jar)  file  from  the  specified  list  of  sources.   Any
              directories in the source list will be searched for .class files).  Any .java files
              in the source list will be compiled  to .class files by calling the Java() Builder.

              If the $JARCHDIR value is set,  the  jar  command  will  change  to  the  specified
              directory  using  the  -C option.  If $JARCHDIR is not set explicitly, &SCons; will
              use the top of any subdirectory tree in which Java .class were built by the  Java()
              Builder.

              If the contents any of the source files begin with the string Manifest-Version, the
              file is assumed to be a manifest and is passed to the jar command with the m option
              set.

              env.Jar(target = 'foo.jar', source = 'classes')

              env.Jar(target = 'bar.jar',
                      source = ['bar1.java', 'bar2.java'])

       Java()

       env.Java()
              Builds  one  or  more  Java  class  files.   The  sources may be any combination of
              explicit .java files, or directory trees which will be scanned for .java files.

              SCons will parse each source .java  file  to  find  the  classes  (including  inner
              classes) defined within that file, and from that figure out the target .class files
              that will be created.  The class files will  be  placed  underneath  the  specified
              target directory.

              SCons  will  also search each Java file for the Java package name, which it assumes
              can be found on a line beginning with the string package in the first  column;  the
              resulting  .class  files  will  be  placed  in a directory reflecting the specified
              package name.  For example, the file Foo.java defining a single  public  Foo  class
              and   containing   a   package  name  of  sub.dir  will  generate  a  corresponding
              sub/dir/Foo.class class file.

              Examples:

              env.Java(target = 'classes', source = 'src')
              env.Java(target = 'classes', source = ['src1', 'src2'])
              env.Java(target = 'classes', source = ['File1.java', 'File2.java'])

              Java source files can use the native encoding for the underlying OS.   Since  SCons
              compiles in simple ASCII mode by default, the compiler will generate warnings about
              unmappable characters, which may lead to errors as the file is  processed  further.
              In  this  case,  the  user  must  specify the LANG environment variable to tell the
              compiler what encoding is used.  For portibility, it's  best  if  the  encoding  is
              hard-coded so that the compile will work if it is done on a system with a different
              encoding.

              env = Environment()
              env['ENV']['LANG'] = 'en_GB.UTF-8'

       JavaH()

       env.JavaH()
              Builds C header and source files for implementing Java native methods.  The  target
              can  be  either  a directory in which the header files will be written, or a header
              file name which will contain all of the definitions.  The source can be  the  names
              of  .class  files,  the  names  of  .java files to be compiled into .class files by
              calling the Java() builder method, or the objects returned from the Java()  builder
              method.

              If  the construction variable $JAVACLASSDIR is set, either in the environment or in
              the call to the JavaH() builder method itself, then the value of the variable  will
              be stripped from the beginning of any .class file names.

              Examples:

              # builds java_native.h
              classes = env.Java(target = 'classdir', source = 'src')
              env.JavaH(target = 'java_native.h', source = classes)

              # builds include/package_foo.h and include/package_bar.h
              env.JavaH(target = 'include',
                        source = ['package/foo.class', 'package/bar.class'])

              # builds export/foo.h and export/bar.h
              env.JavaH(target = 'export',
                        source = ['classes/foo.class', 'classes/bar.class'],
                        JAVACLASSDIR = 'classes')

       Library()

       env.Library()
              A synonym for the StaticLibrary() builder method.

       LoadableModule()

       env.LoadableModule()
              On  most  systems,  this  is  the  same  as  SharedLibrary().  On Mac OS X (Darwin)
              platforms, this creates a loadable module bundle.

       M4()

       env.M4()
              Builds an output file from an M4 input file.  This uses a default $M4FLAGS value of
              -E,  which  considers  all warnings to be fatal and stops on the first warning when
              using the GNU version of m4.  Example:

              env.M4(target = 'foo.c', source = 'foo.c.m4')

       Moc()

       env.Moc()
              Builds an output file from a moc input file. Moc  input  files  are  either  header
              files  or  cxx files. This builder is only available after using the tool 'qt'. See
              the $QTDIR variable for more information.  Example:

              env.Moc('foo.h') # generates moc_foo.cc
              env.Moc('foo.cpp') # generates foo.moc

       MSVSProject()

       env.MSVSProject()
              Builds a Microsoft Visual Studio project file, and by  default  builds  a  solution
              file as well.

              This  builds  a  Visual  Studio project file, based on the version of Visual Studio
              that is configured (either the latest installed version, or the  version  specified
              by  $MSVS_VERSION  in  the  Environment constructor).  For Visual Studio 6, it will
              generate a .dsp file.  For Visual Studio 7  (.NET)  and  later  versions,  it  will
              generate a .vcproj file.

              By  default,  this also generates a solution file for the specified project, a .dsw
              file for Visual Studio 6 or a .sln file for Visual Studio 7 (.NET).  This  behavior
              may be disabled by specifying auto_build_solution=0 when you call MSVSProject(), in
              which case you presumably want  to  build  the  solution  file(s)  by  calling  the
              MSVSSolution() Builder (see below).

              The  MSVSProject()  builder  takes several lists of filenames to be placed into the
              project file.  These are currently limited to srcs, incs, localincs, resources, and
              misc.   These  are pretty self-explanatory, but it should be noted that these lists
              are added to the $SOURCES construction variable  as  strings,  NOT  as  SCons  File
              Nodes.   This is because they represent file names to be added to the project file,
              not the source files used to build the project file.

              The above filename lists are all optional, although at least one must be  specified
              for the resulting project file to be non-empty.

              In addition to the above lists of values, the following values may be specified:

              target:  The  name  of the target .dsp or .vcproj file.  The correct suffix for the
              version of Visual Studio must be  used,  but  the  $MSVSPROJECTSUFFIX  construction
              variable will be defined to the correct value (see example below).

              variant:  The  name of this particular variant.  For Visual Studio 7 projects, this
              can also be a list of variant names.  These are typically things  like  "Debug"  or
              "Release", but really can be anything you want.  For Visual Studio 7 projects, they
              may also specify a target platform separated from the variant name by a | (vertical
              pipe) character: Debug|Xbox.  The default target platform is Win32.  Multiple calls
              to MSVSProject() with different variants are allowed; all variants will be added to
              the project file with their appropriate build targets and sources.

              buildtarget:  An  optional string, node, or list of strings or nodes (one per build
              variant), to tell the Visual Studio debugger what output  target  to  use  in  what
              build  variant.  The number of buildtarget entries must match the number of variant
              entries.

              runfile: The name of the file that Visual Studio 7 and later will  run  and  debug.
              This  appears  as  the  value  of  the  Output field in the resutling Visual Studio
              project file.  If this is not specified, the default is the same as  the  specified
              buildtarget value.

              Note  that because &SCons; always executes its build commands from the directory in
              which the SConstruct file is located, if you generate a project file in a different
              directory  than the SConstruct directory, users will not be able to double-click on
              the file name in compilation error messages displayed in the Visual Studio  console
              output window.  This can be remedied by adding the Visual C/C++ /FC compiler option
              to the $CCFLAGS  variable so that the compiler will print the full path name of any
              files that cause compilation errors.

              Example usage:

              barsrcs = ['bar.cpp'],
              barincs = ['bar.h'],
              barlocalincs = ['StdAfx.h']
              barresources = ['bar.rc','resource.h']
              barmisc = ['bar_readme.txt']

              dll = env.SharedLibrary(target = 'bar.dll',
                                      source = barsrcs)

              env.MSVSProject(target = 'Bar' + env['MSVSPROJECTSUFFIX'],
                              srcs = barsrcs,
                              incs = barincs,
                              localincs = barlocalincs,
                              resources = barresources,
                              misc = barmisc,
                              buildtarget = dll,
                              variant = 'Release')

       MSVSSolution()

       env.MSVSSolution()
              Builds a Microsoft Visual Studio solution file.

              This  builds  a  Visual Studio solution file, based on the version of Visual Studio
              that is configured (either the latest installed version, or the  version  specified
              by  $MSVS_VERSION  in  the construction environment).  For Visual Studio 6, it will
              generate a .dsw file.  For Visual Studio 7 (.NET), it will generate a .sln file.

              The following values must be specified:

              target: The name of the target .dsw or .sln  file.   The  correct  suffix  for  the
              version  of  Visual  Studio must be used, but the value $MSVSSOLUTIONSUFFIX will be
              defined to the correct value (see example below).

              variant: The name of this particular variant, or  a  list  of  variant  names  (the
              latter  is  only  supported  for MSVS 7 solutions). These are typically things like
              "Debug" or "Release", but really can be anything you want. For MSVS 7 they may also
              specify target platform, like this "Debug|Xbox". Default platform is Win32.

              projects:  A  list of project file names, or Project nodes returned by calls to the
              MSVSProject() Builder, to be placed into the solution file.   It  should  be  noted
              that these file names are NOT added to the $SOURCES environment variable in form of
              files, but rather as strings.   This is because they represent  file  names  to  be
              added to the solution file, not the source files used to build the solution file.

              Example Usage:

              env.MSVSSolution(target = 'Bar' + env['MSVSSOLUTIONSUFFIX'],
                               projects = ['bar' + env['MSVSPROJECTSUFFIX']],
                               variant = 'Release')

       Object()

       env.Object()
              A synonym for the StaticObject() builder method.

       Package()

       env.Package()
              Builds  software  distribution  packages.  Packages consist of files to install and
              packaging information.  The former may be specified with the source  parameter  and
              may  be  left out, in which case the &FindInstalledFiles; function will collect all
              files that have an Install() or InstallAs() Builder attached.  If the target is not
              specified it will be deduced from additional information given to this Builder.

              The  packaging  information  is  specified  with the help of construction variables
              documented below.  This information is called a tag to stress that some of them can
              also  be  attached  to  files  with  the  &Tag;  function.  The mandatory ones will
              complain if they  were  not  specified.   They  vary  depending  on  chosen  target
              packager.

              The  target  packager may be selected with the "PACKAGETYPE" command line option or
              with the $PACKAGETYPE construction  variable.  Currently  the  following  packagers
              available:

               * msi - Microsoft Installer
               * rpm - Redhat Package Manger
               * ipkg - Itsy Package Management System
               * tarbz2 - compressed tar
               * targz - compressed tar
               * zip - zip file
               * src_tarbz2 - compressed tar source
               * src_targz - compressed tar source
               * src_zip - zip file source

              An  updated  list  is always available under the "package_type" option when running
              "scons --help" on a project that has packaging activated.
              env = Environment(tools=['default', 'packaging'])
              env.Install('/bin/', 'my_program')
              env.Package( NAME           = 'foo',
                           VERSION        = '1.2.3',
                           PACKAGEVERSION = 0,
                           PACKAGETYPE    = 'rpm',
                           LICENSE        = 'gpl',
                           SUMMARY        = 'balalalalal',
                           DESCRIPTION    = 'this should be really really long',
                           X_RPM_GROUP    = 'Application/fu',
                           SOURCE_URL     = 'http://foo.org/foo-1.2.3.tar.gz'
                      )

       PCH()

       env.PCH()
              Builds a Microsoft Visual C++ precompiled  header.   Calling  this  builder  method
              returns a list of two targets: the PCH as the first element, and the object file as
              the second element. Normally the object file is ignored.  This  builder  method  is
              only  provided  when  Microsoft  Visual C++ is being used as the compiler.  The PCH
              builder method is generally used in conjuction with the PCH  construction  variable
              to force object files to use the precompiled header:

              env['PCH'] = env.PCH('StdAfx.cpp')[0]

       PDF()

       env.PDF()
              Builds  a  .pdf  file  from  a  .dvi input file (or, by extension, a .tex, .ltx, or
              .latex input file).  The suffix specified by the $PDFSUFFIX  construction  variable
              (.pdf  by  default)  is  added  automatically  to  the  target if it is not already
              present.  Example:

              # builds from aaa.tex
              env.PDF(target = 'aaa.pdf', source = 'aaa.tex')
              # builds bbb.pdf from bbb.dvi
              env.PDF(target = 'bbb', source = 'bbb.dvi')

       PostScript()

       env.PostScript()
              Builds a .ps file from a .dvi input file (or, by extension, a .tex, .ltx, or .latex
              input  file).   The suffix specified by the $PSSUFFIX construction variable (.ps by
              default) is added automatically to  the  target  if  it  is  not  already  present.
              Example:

              # builds from aaa.tex
              env.PostScript(target = 'aaa.ps', source = 'aaa.tex')
              # builds bbb.ps from bbb.dvi
              env.PostScript(target = 'bbb', source = 'bbb.dvi')

       Program()

       env.Program()
              Builds an executable given one or more object files or C, C++, D, or Fortran source
              files.  If any C, C++, D or Fortran source files are specified, then they  will  be
              automatically  compiled to object files using the Object() builder method; see that
              builder method's description for a list of legal source file suffixes and how  they
              are  interpreted.   The target executable file prefix (specified by the $PROGPREFIX
              construction variable; nothing by default) and suffix (specified by the $PROGSUFFIX
              construction  variable;  by  default,  .exe  on  Windows  systems, nothing on POSIX
              systems) are automatically added to the target if not already present.  Example:

              env.Program(target = 'foo', source = ['foo.o', 'bar.c', 'baz.f'])

       RES()

       env.RES()
              Builds a Microsoft Visual C++ resource file.  This builder method is only  provided
              when  Microsoft  Visual C++ or MinGW is being used as the compiler. The .res (or .o
              for MinGW) suffix is added to the target name if no other  suffix  is  given.   The
              source  file  is  scanned  for  implicit  dependencies  as though it were a C file.
              Example:

              env.RES('resource.rc')

       RMIC()

       env.RMIC()
              Builds stub and skeleton class files for remote objects  from  Java  .class  files.
              The  target is a directory relative to which the stub and skeleton class files will
              be written.  The source can be the names of .class files,  or  the  objects  return
              from the Java() builder method.

              If  the construction variable $JAVACLASSDIR is set, either in the environment or in
              the call to the RMIC() builder method itself, then the value of the  variable  will
              be stripped from the beginning of any .class file names.

              classes = env.Java(target = 'classdir', source = 'src')
              env.RMIC(target = 'outdir1', source = classes)

              env.RMIC(target = 'outdir2',
                       source = ['package/foo.class', 'package/bar.class'])

              env.RMIC(target = 'outdir3',
                       source = ['classes/foo.class', 'classes/bar.class'],
                       JAVACLASSDIR = 'classes')

       RPCGenClient()

       env.RPCGenClient()
              Generates  an RPC client stub (_clnt.c) file from a specified RPC (.x) source file.
              Because rpcgen only builds output files in the local directory, the command will be
              executed in the source file's directory by default.

              # Builds src/rpcif_clnt.c
              env.RPCGenClient('src/rpcif.x')

       RPCGenHeader()

       env.RPCGenHeader()
              Generates  an  RPC header (.h) file from a specified RPC (.x) source file.  Because
              rpcgen only builds output files  in  the  local  directory,  the  command  will  be
              executed in the source file's directory by default.

              # Builds src/rpcif.h
              env.RPCGenHeader('src/rpcif.x')

       RPCGenService()

       env.RPCGenService()
              Generates  an  RPC  server-skeleton  (_svc.c) file from a specified RPC (.x) source
              file.  Because rpcgen only builds output files in the local directory, the  command
              will be executed in the source file's directory by default.

              # Builds src/rpcif_svc.c
              env.RPCGenClient('src/rpcif.x')

       RPCGenXDR()

       env.RPCGenXDR()
              Generates  an  RPC XDR routine (_xdr.c) file from a specified RPC (.x) source file.
              Because rpcgen only builds output files in the local directory, the command will be
              executed in the source file's directory by default.

              # Builds src/rpcif_xdr.c
              env.RPCGenClient('src/rpcif.x')

       SharedLibrary()

       env.SharedLibrary()
              Builds  a shared library (.so on a POSIX system, .dll on Windows) given one or more
              object files or C, C++, D or Fortran source files.  If any source files are  given,
              then  they  will  be  automatically  compiled  to object files.  The static library
              prefix and suffix (if any) are automatically  added  to  the  target.   The  target
              library  file  prefix  (specified  by  the  $SHLIBPREFIX  construction variable; by
              default, lib on POSIX systems, nothing on Windows systems) and suffix (specified by
              the $SHLIBSUFFIX construction variable; by default, .dll on Windows systems, .so on
              POSIX systems) are automatically added  to  the  target  if  not  already  present.
              Example:

              env.SharedLibrary(target = 'bar', source = ['bar.c', 'foo.o'])

              On  Windows systems, the SharedLibrary() builder method will always build an import
              (.lib) library in addition to the shared (.dll) library, adding a .lib library with
              the  same  basename  if  there  is not already a .lib file explicitly listed in the
              targets.

              Any object files listed in the source must have been built  for  a  shared  library
              (that  is,  using the SharedObject() builder method).  scons will raise an error if
              there is any mismatch.

              On some platforms,  there  is  a  distinction  between  a  shared  library  (loaded
              automatically  by  the system to resolve external references) and a loadable module
              (explicitly  loaded  by  user  action).    For   maximum   portability,   use   the
              LoadableModule() builder for the latter.

              On  Windows  systems,  specifying  register=1  will cause the .dll to be registered
              after it is built using REGSVR32.  The command that is run ("regsvr32" by  default)
              is determined by $REGSVR construction variable, and the flags passed are determined
              by $REGSVRFLAGS.  By default, $REGSVRFLAGS  includes  the  /s  option,  to  prevent
              dialogs from popping up and requiring user attention when it is run.  If you change
              $REGSVRFLAGS, be sure to include the /s option.  For example,

              env.SharedLibrary(target = 'bar',
                                source = ['bar.cxx', 'foo.obj'],
                                register=1)

              will register bar.dll as a COM object when it is done linking it.

       SharedObject()

       env.SharedObject()
              Builds an object file for inclusion in a shared library.  Source  files  must  have
              one  of  the  same set of extensions specified above for the StaticObject() builder
              method.  On some platforms building a shared object  requires  additional  compiler
              option  (e.g. -fPIC for gcc) in addition to those needed to build a normal (static)
              object, but on some platforms there is no difference between a shared object and  a
              normal  (static)  one.  When  there  is  a difference, SCons will only allow shared
              objects to be linked into a shared library, and will use  a  different  suffix  for
              shared  objects.  On  platforms where there is no difference, SCons will allow both
              normal (static) and shared objects to be linked into a shared library, and will use
              the  same  suffix  for  shared and normal (static) objects.  The target object file
              prefix (specified by the $SHOBJPREFIX construction variable; by default,  the  same
              as $OBJPREFIX) and suffix (specified by the $SHOBJSUFFIX construction variable) are
              automatically added to the target if not already present.  Examples:

              env.SharedObject(target = 'ddd', source = 'ddd.c')
              env.SharedObject(target = 'eee.o', source = 'eee.cpp')
              env.SharedObject(target = 'fff.obj', source = 'fff.for')

              Note that the source files will be scanned according to the suffix mappings in  the
              SourceFileScanner  object.   See  the  section  "Scanner  Objects," below, for more
              information.

       StaticLibrary()

       env.StaticLibrary()
              Builds a static library given one or more object files or  C,  C++,  D  or  Fortran
              source  files.   If  any  source  files  are given, then they will be automatically
              compiled to object files.  The static  library  prefix  and  suffix  (if  any)  are
              automatically  added  to  the target.  The target library file prefix (specified by
              the $LIBPREFIX construction variable; by default, lib on POSIX systems, nothing  on
              Windows  systems) and suffix (specified by the $LIBSUFFIX construction variable; by
              default, .lib on Windows systems, .a on POSIX systems) are automatically  added  to
              the target if not already present.  Example:

              env.StaticLibrary(target = 'bar', source = ['bar.c', 'foo.o'])

              Any  object  files  listed  in the source must have been built for a static library
              (that is, using the StaticObject() builder method).  scons will raise an  error  if
              there is any mismatch.

       StaticObject()

       env.StaticObject()
              Builds  a  static  object file from one or more C, C++, D, or Fortran source files.
              Source files must have one of the following extensions:

                .asm    assembly language file
                .ASM    assembly language file
                .c      C file
                .C      Windows:  C file
                        POSIX:  C++ file
                .cc     C++ file
                .cpp    C++ file
                .cxx    C++ file
                .cxx    C++ file
                .c++    C++ file
                .C++    C++ file
                .d      D file
                .f      Fortran file
                .F      Windows:  Fortran file
                        POSIX:  Fortran file + C pre-processor
                .for    Fortran file
                .FOR    Fortran file
                .fpp    Fortran file + C pre-processor
                .FPP    Fortran file + C pre-processor
                .m      Object C file
                .mm     Object C++ file
                .s      assembly language file
                .S      Windows:  assembly language file
                        ARM: CodeSourcery Sourcery Lite
                .sx     assembly language file + C pre-processor
                        POSIX:  assembly language file + C pre-processor
                .spp    assembly language file + C pre-processor
                .SPP    assembly language file + C pre-processor

              The target object file prefix (specified by the $OBJPREFIX  construction  variable;
              nothing  by default) and suffix (specified by the $OBJSUFFIX construction variable;
              .obj on Windows systems, .o on POSIX systems) are automatically added to the target
              if not already present.  Examples:

              env.StaticObject(target = 'aaa', source = 'aaa.c')
              env.StaticObject(target = 'bbb.o', source = 'bbb.c++')
              env.StaticObject(target = 'ccc.obj', source = 'ccc.f')

              Note  that  the  source  files  will be scanned according to the suffix mappings in
              SourceFileScanner object.  See the  section  "Scanner  Objects,"  below,  for  more
              information.

       Substfile()

       env.Substfile()
              The  Substfile()  builder  generates a single text file by concatenating the source
              files.  Nested lists of sources are flattened.  $LINESEPARATOR is used to  separate
              the source files; see the description of Textfile() for details.

              If  a  single source file is present with an .in suffix, the suffix is stripped and
              the remainder is used as the default target name.

              The prefix and  suffix  specified  by  the  $SUBSTFILEPREFIX  and  $SUBSTFILESUFFIX
              construction variables (the null string by default in both cases) are automatically
              added to the target if they are not already present.

              If a construction variable named $SUBST_DICT is present, it may be either a  Python
              dictionary  or  a sequence of (key,value) tuples.  If the former, the dictionary is
              converted into a list of tuples in an arbitrary order, so if one key is a prefix of
              another   key  or  if  one  substitution  could  be  further  expanded  by  another
              subsitition, it is unpredictible whether the expansion will occur.

              Any occurences in the source of a key are  replaced  by  the  corresponding  value,
              which  may be a Python callable function or a string.  If a value is a function, it
              is first called (with no arguments) to produce a  string.   The  string  is  subst-
              expanded and the result replaces the key.

              env = Environment(tools = ['default', 'textfile'])

              env['prefix'] = '/usr/bin'
              script_dict = {'@prefix@': '/bin', @exec_prefix@: '$prefix'}
              env.Substfile('script.in', SUBST_DICT = script_dict)

              conf_dict = {'%VERSION%': '1.2.3', '%BASE%': 'MyProg'}
              env.Substfile('config.h.in', conf_dict, SUBST_DICT = conf_dict)

              # UNPREDICTABLE - one key is a prefix of another
              bad_foo = {'$foo': '$foo', '$foobar': '$foobar'}
              env.Substfile('foo.in', SUBST_DICT = bad_foo)

              # PREDICTABLE - keys are applied longest first
              good_foo = [('$foobar', '$foobar'), ('$foo', '$foo')]
              env.Substfile('foo.in', SUBST_DICT = good_foo)

              # UNPREDICTABLE - one substitution could be futher expanded
              bad_bar = {'@bar@': '@soap@', '@soap@': 'lye'}
              env.Substfile('bar.in', SUBST_DICT = bad_bar)

              # PREDICTABLE - substitutions are expanded in order
              good_bar = (('@bar@', '@soap@'), ('@soap@', 'lye'))
              env.Substfile('bar.in', SUBST_DICT = good_bar)

              # the SUBST_DICT may be in common (and not an override)
              substutions = {}
              subst = Environment(tools = ['textfile', SUBST_DICT = substitutions)
              substitutions['@foo@'] = 'foo'
              subst['SUBST_DICT']['@bar@'] = 'bar'
              subst.Substfile('pgm1.c', [Value('#include "@foo@.h"'),
                                         Value('#include "@bar@.h"'),
                                         "common.in",
                                         "pgm1.in"
                                        ])
              subst.Substfile('pgm2.c', [Value('#include "@foo@.h"'),
                                         Value('#include "@bar@.h"'),
                                         "common.in",
                                         "pgm2.in"
                                        ])

       Tar()

       env.Tar()
              Builds  a  tar  archive  of  the  specified  files and/or directories.  Unlike most
              builder methods, the Tar() builder method may be called multiple times for a  given
              target;  each  additional  call adds to the list of entries that will be built into
              the archive.  Any source directories will be scanned for  changes  to  any  on-disk
              files,  regardless  of  whether or not scons knows about them from other Builder or
              function calls.

              env.Tar('src.tar', 'src')

              # Create the stuff.tar file.
              env.Tar('stuff', ['subdir1', 'subdir2'])
              # Also add "another" to the stuff.tar file.
              env.Tar('stuff', 'another')

              # Set TARFLAGS to create a gzip-filtered archive.
              env = Environment(TARFLAGS = '-c -z')
              env.Tar('foo.tar.gz', 'foo')

              # Also set the suffix to .tgz.
              env = Environment(TARFLAGS = '-c -z',
                                TARSUFFIX = '.tgz')
              env.Tar('foo')

       Textfile()

       env.Textfile()
              The Textfile() builder generates a single text file.  The source strings constitute
              the  lines;  nested  lists  of  sources  are  flattened.  $LINESEPARATOR is used to
              separate the strings.

              If present, the $SUBST_DICT construction variable is used  to  modify  the  strings
              before they are written; see the Substfile() description for details.

              The  prefix  and  suffix  specified  by  the  $TEXTFILEPREFIX  and  $TEXTFILESUFFIX
              construction variables (the null string and  .txt  by  default,  respectively)  are
              automatically added to the target if they are not already present.  Examples:

              # builds/writes foo.txt
              env.Textfile(target = 'foo.txt', source = ['Goethe', 42, 'Schiller'])

              # builds/writes bar.txt
              env.Textfile(target = 'bar',
                           source = ['lalala', 'tanteratei'],
                           LINESEPARATOR='|*')

              # nested lists are flattened automatically
              env.Textfile(target = 'blob',
                           source = ['lalala', ['Goethe', 42 'Schiller'], 'tanteratei'])

              # files may be used as input by wraping them in File()
              env.Textfile(target = 'concat',  # concatenate files with a marker between
                           source = [File('concat1'), File('concat2')],
                           LINESEPARATOR = '====================\n')

              Results are:
              foo.txt
                ....8<----
                Goethe
                42
                Schiller
                ....8<---- (no linefeed at the end)

              bar.txt:
                ....8<----
                lalala|*tanteratei
                ....8<---- (no linefeed at the end)

              blob.txt
                ....8<----
                lalala
                Goethe
                42
                Schiller
                tanteratei
                ....8<---- (no linefeed at the end)

       TypeLibrary()

       env.TypeLibrary()
              Builds  a  Windows  type  library  (.tlb)  file  from an input IDL file (.idl).  In
              addition, it will build the associated inteface stub and proxy source files, naming
              them according to the base name of the .idl file.  For example,

              env.TypeLibrary(source="foo.idl")

              Will create foo.tlb, foo.h, foo_i.c, foo_p.c and foo_data.c files.

       Uic()

       env.Uic()
              Builds  a  header file, an implementation file and a moc file from an ui file.  and
              returns the corresponding nodes in the above order.  This builder is only available
              after using the tool 'qt'. Note: you can specify .ui files directly as source files
              to the  Program(),  Library()  and  SharedLibrary()  builders  without  using  this
              builder.  Using  this builder lets you override the standard naming conventions (be
              careful: prefixes are always prepended to names of built files; if you  don't  want
              prefixes,  you  may set them to ``).  See the $QTDIR variable for more information.
              Example:

              env.Uic('foo.ui') # -> ['foo.h', 'uic_foo.cc', 'moc_foo.cc']
              env.Uic(target = Split('include/foo.h gen/uicfoo.cc gen/mocfoo.cc'),
                      source = 'foo.ui') # -> ['include/foo.h', 'gen/uicfoo.cc', 'gen/mocfoo.cc']

       Zip()

       env.Zip()
              Builds a zip archive of  the  specified  files  and/or  directories.   Unlike  most
              builder  methods, the Zip() builder method may be called multiple times for a given
              target; each additional call adds to the list of entries that will  be  built  into
              the  archive.   Any  source  directories will be scanned for changes to any on-disk
              files, regardless of whether or not scons knows about them from  other  Builder  or
              function calls.

              env.Zip('src.zip', 'src')

              # Create the stuff.zip file.
              env.Zip('stuff', ['subdir1', 'subdir2'])
              # Also add "another" to the stuff.tar file.
              env.Zip('stuff', 'another')

       All  targets  of  builder  methods  automatically  depend  on  their sources.  An explicit
       dependency can be specified using the Depends method of a  construction  environment  (see
       below).

       In  addition, scons automatically scans source files for various programming languages, so
       the dependencies do not need to be specified explicitly.  By default, SCons can  C  source
       files,  C++ source files, Fortran source files with .F (POSIX systems only), .fpp, or .FPP
       file extensions, and assembly language files with .S (POSIX systems only), .spp,  or  .SPP
       files  extensions  for  C  preprocessor  dependencies.  SCons also has default support for
       scanning D source files, You  can  also  write  your  own  Scanners  to  add  support  for
       additional  source  file  types.  These can be added to the default Scanner object used by
       the  Object(),  StaticObject(),  and  SharedObject()  Builders  by  adding  them  to   the
       SourceFileScanner  object.   See the section "Scanner Objects" below, for more information
       about defining your own Scanner objects and using the SourceFileScanner object.

   Methods and Functions to Do Things
       In addition to Builder methods, scons provides a number of other construction  environment
       methods and global functions to manipulate the build configuration.

       Usually,  a  construction  environment  method and global function with the same name both
       exist so that you don't have to remember whether to a specific bit of  functionality  must
       be  called with or without a construction environment.  In the following list, if you call
       something as a global function it looks like:
              Function(arguments)
       and if you call something through a construction environment it looks like:
              env.Function(arguments)
       If you can call the functionality in both ways, then both forms are listed.

       Global functions may be called  from  custom  Python  modules  that  you  import  into  an
       SConscript file by adding the following to the Python module:

              from SCons.Script import *

       Except  where  otherwise  noted, the same-named construction environment method and global
       function provide the exact  same  functionality.   The  only  difference  is  that,  where
       appropriate,  calling the functionality through a construction environment will substitute
       construction variables into any supplied strings.  For example:

              env = Environment(FOO = 'foo')
              Default('$FOO')
              env.Default('$FOO')

       In the above example, the first call to the global Default() function will actually add  a
       target  named  $FOO  to  the  list  of  default  targets,  while  the  second  call to the
       env.Default() construction environment method will expand the value and add a target named
       foo  to the list of default targets.  For more on construction variable expansion, see the
       next section on construction variables.

       Construction environment methods and global functions supported by scons include:

       Action(action, [cmd/str/fun, [var, ...]] [option=value, ...])

       env.Action(action, [cmd/str/fun, [var, ...]] [option=value, ...])
              Creates an Action object  for  the  specified  action.   See  the  section  "Action
              Objects," below, for a complete explanation of the arguments and behavior.

              Note  that  the  env.Action()  form  of  the  invocation  will  expand construction
              variables in any argument strings, including the action argument, at the time it is
              called using the construction variables in the env construction environment through
              which env.Action() was called.  The Action() form  delays  all  variable  expansion
              until the Action object is actually used.

       AddMethod(object, function, [name])

       env.AddMethod(function, [name])
              When called with the AddMethod() form, adds the specified function to the specified
              object as the specified method name.  When called with  the  env.AddMethod()  form,
              adds  the  specified  function to the construction environment env as the specified
              method name.  In both cases, if name is omitted or None, the name of the  specified
              function itself is used for the method name.

              Examples:

              # Note that the first argument to the function to
              # be attached as a method must be the object through
              # which the method will be called; the Python
              # convention is to call it 'self'.
              def my_method(self, arg):
                  print "my_method() got", arg

              # Use the global AddMethod() function to add a method
              # to the Environment class.  This
              AddMethod(Environment, my_method)
              env = Environment()
              env.my_method('arg')

              # Add the function as a method, using the function
              # name for the method call.
              env = Environment()
              env.AddMethod(my_method, 'other_method_name')
              env.other_method_name('another arg')

       AddOption(arguments)
              This  function  adds  a  new  command-line  option to be recognized.  The specified
              arguments are the same as supported by the  standard  Python  optparse.add_option()
              method  (with a few additional capabilities noted below); see the documentation for
              optparse for a thorough discussion of its option-processing capabities.

              In addition to the arguments and  values  supported  by  the  optparse.add_option()
              method, the SCons AddOption() function allows you to set the nargs keyword value to
              '?'  (a string with just the question mark) to indicate  that  the  specified  long
              option(s)  take(s)  an  optional  argument.   When  nargs  =  '?'  is passed to the
              AddOption() function, the  const  keyword  argument  may  be  used  to  supply  the
              "default"  value  that  should  be used when the option is specified on the command
              line without an explicit argument.

              If no default= keyword argument is supplied when calling  AddOption(),  the  option
              will have a default value of None.

              Once  a  new  command-line option has been added with AddOption(), the option value
              may be accessed using GetOption() or env.GetOption().  The value may also  be  set,
              using  SetOption()  or  env.SetOption(),  if  conditions  in  a  SConscript require
              overriding any default value.  Note, however, that a value specified on the command
              line will always override a value set by any SConscript file.

              Any specified help= strings for the new option(s) will be displayed by the -H or -h
              options (the latter only if no other help  text  is  specified  in  the  SConscript
              files).   The  help text for the local options specified by AddOption() will appear
              below the SCons options themselves, under a separate Local  Options  heading.   The
              options  will  appear  in the help text in the order in which the AddOption() calls
              occur.

              Example:

              AddOption('--prefix',
                        dest='prefix',
                        nargs=1, type='string',
                        action='store',
                        metavar='DIR',
                        help='installation prefix')
              env = Environment(PREFIX = GetOption('prefix'))

       AddPostAction(target, action)

       env.AddPostAction(target, action)
              Arranges for the specified action to be performed after the  specified  target  has
              been  built.  The specified action(s) may be an Action object, or anything that can
              be converted into an Action object (see below).

              When multiple targets are supplied, the action may be called multiple  times,  once
              after each action that generates one or more targets in the list.

       AddPreAction(target, action)

       env.AddPreAction(target, action)
              Arranges  for  the  specified action to be performed before the specified target is
              built.  The specified action(s) may be an Action object, or anything  that  can  be
              converted into an Action object (see below).

              When  multiple  targets  are specified, the action(s) may be called multiple times,
              once before each action that generates one or more targets in the list.

              Note that if any of the targets are built in multiple steps,  the  action  will  be
              invoked  just  before  the "final" action that specifically generates the specified
              target(s).  For example, when building  an  executable  program  from  a  specified
              source .c file via an intermediate object file:

              foo = Program('foo.c')
              AddPreAction(foo, 'pre_action')

              The specified pre_action would be executed before scons calls the link command that
              actually generates the executable program binary  foo,  not  before  compiling  the
              foo.c file into an object file.

       Alias(alias, [targets, [action]])

       env.Alias(alias, [targets, [action]])
              Creates  one  or  more  phony targets that expand to one or more other targets.  An
              optional action (command) or list of actions can be specified that will be executed
              whenever  the  any  of  the alias targets are out-of-date.  Returns the Node object
              representing the alias, which exists outside of any file system.  This Node object,
              or  the  alias  name,  may  be  used as a dependency of any other target, including
              another alias.  Alias() can be called multiple times for  the  same  alias  to  add
              additional targets to the alias, or additional actions to the list for this alias.

              Examples:

              Alias('install')
              Alias('install', '/usr/bin')
              Alias(['install', 'install-lib'], '/usr/local/lib')

              env.Alias('install', ['/usr/local/bin', '/usr/local/lib'])
              env.Alias('install', ['/usr/local/man'])

              env.Alias('update', ['file1', 'file2'], "update_database $SOURCES")

       AllowSubstExceptions([exception, ...])
              Specifies   the  exceptions  that  will  be  allowed  when  expanding  construction
              variables.  By default,  any  construction  variable  expansions  that  generate  a
              NameError or IndexError exception will expand to a '' (a null string) and not cause
              scons to fail.  All exceptions not in the specified list  will  generate  an  error
              message and terminate processing.

              If AllowSubstExceptions() is called multiple times, each call completely overwrites
              the previous list of allowed exceptions.

              Example:

              # Requires that all construction variable names exist.
              # (You may wish to do this if you want to enforce strictly
              # that all construction variables must be defined before use.)
              AllowSubstExceptions()

              # Also allow a string containing a zero-division expansion
              # like '${1 / 0}' to evalute to ''.
              AllowSubstExceptions(IndexError, NameError, ZeroDivisionError)

       AlwaysBuild(target, ...)

       env.AlwaysBuild(target, ...)
              Marks each given target so that it is always assumed to be out of  date,  and  will
              always  be  rebuilt  if needed.  Note, however, that AlwaysBuild() does not add its
              target(s) to the default target list, so the targets will only be built if they are
              specified  on  the  command  line,  or are a dependent of a target specified on the
              command line--but they will always be built if so specified.  Multiple targets  can
              be passed in to a single call to AlwaysBuild().

       env.Append(key=val, [...])
              Appends the specified keyword arguments to the end of construction variables in the
              environment.  If the Environment does not have the specified construction variable,
              it  is simply added to the environment.  If the values of the construction variable
              and the keyword argument are the same type, then the  two  values  will  be  simply
              added  together.  Otherwise, the construction variable and the value of the keyword
              argument are both coerced to lists, and the lists are added  together.   (See  also
              the Prepend method, below.)

              Example:

              env.Append(CCFLAGS = ' -g', FOO = ['foo.yyy'])

       env.AppendENVPath(name, newpath, [envname, sep, delete_existing])
              This  appends  new  path  elements  to  the  given  path  in the specified external
              environment (ENV by default).  This will only add any particular path once (leaving
              the  last  one it encounters and ignoring the rest, to preserve path order), and to
              help  assure  this,  will  normalize  all   paths   (using   os.path.normpath   and
              os.path.normcase).  This can also handle the case where the given old path variable
              is a list instead of a string, in which case a list will be returned instead  of  a
              string.

              If delete_existing is 0, then adding a path that already exists will not move it to
              the end; it will stay where it is in the list.

              Example:

              print 'before:',env['ENV']['INCLUDE']
              include_path = '/foo/bar:/foo'
              env.AppendENVPath('INCLUDE', include_path)
              print 'after:',env['ENV']['INCLUDE']

              yields:
              before: /foo:/biz
              after: /biz:/foo/bar:/foo

       env.AppendUnique(key=val, [...], delete_existing=0)
              Appends the specified keyword arguments to the end of construction variables in the
              environment.  If the Environment does not have the specified construction variable,
              it is simply added to the environment.  If the construction variable being appended
              to  is  a  list,  then any value(s) that already exist in the construction variable
              will not be added again to the list.  However, if delete_existing  is  1,  existing
              matching  values  are removed first, so existing values in the arg list move to the
              end of the list.

              Example:

              env.AppendUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])

       env.BitKeeper()
              A factory function that returns a Builder object to be used to fetch  source  files
              using BitKeeper.  The returned Builder is intended to be passed to the SourceCode()
              function.

              This function is deprecated.  For details,  see  the  entry  for  the  SourceCode()
              function.

              Example:

              env.SourceCode('.', env.BitKeeper())

       BuildDir(build_dir, src_dir, [duplicate])

       env.BuildDir(build_dir, src_dir, [duplicate])
              Deprecated  synonyms for VariantDir() and env.VariantDir().  The build_dir argument
              becomes the variant_dir argument of VariantDir() or env.VariantDir().

       Builder(action, [arguments])

       env.Builder(action, [arguments])
              Creates a Builder object for  the  specified  action.   See  the  section  "Builder
              Objects," below, for a complete explanation of the arguments and behavior.

              Note  that  the  env.Builder()  form  of  the  invocation  will expand construction
              variables in any arguments strings, including the action argument, at the  time  it
              is  called  using  the  construction  variables in the env construction environment
              through which env.Builder() was called.  The Builder()  form  delays  all  variable
              expansion until after the Builder object is actually called.

       CacheDir(cache_dir)

       env.CacheDir(cache_dir)
              Specifies  that  scons  will  maintain  a cache of derived files in cache_dir.  The
              derived files in the cache will be shared among  all  the  builds  using  the  same
              CacheDir() call.  Specifying a cache_dir of None disables derived file caching.

              Calling  env.CacheDir()  will  only  affect  targets  built  through  the specified
              construction environment.  Calling CacheDir() sets a global default  that  will  be
              used  by  all  targets  built through construction environments that do not have an
              env.CacheDir() specified.

              When a CacheDir() is being used and scons finds a derived file  that  needs  to  be
              rebuilt,  it will first look in the cache to see if a derived file has already been
              built from identical input files and an identical  build  action  (as  incorporated
              into the MD5 build signature).  If so, scons will retrieve the file from the cache.
              If the derived file is not present in the cache, scons will  rebuild  it  and  then
              place  a  copy  of  the  built  file  in  the  cache  (identified  by its MD5 build
              signature), so that it may be retrieved by other builds that need to build the same
              derived file from identical inputs.

              Use  of  a  specified  CacheDir()  may  be disabled for any invocation by using the
              --cache-disable option.

              If the --cache-force option is used, scons will place a copy of all  derived  files
              in  the  cache, even if they already existed and were not built by this invocation.
              This is useful to populate a cache the first time CacheDir() is added to  a  build,
              or after using the --cache-disable option.

              When using CacheDir(), scons will report, "Retrieved `file' from cache," unless the
              --cache-show option is being used.  When the --cache-show  option  is  used,  scons
              will  print  the  action  that  would have been used to build the file, without any
              indication that the file was actually retrieved from the cache.  This is useful  to
              generate  build logs that are equivalent regardless of whether a given derived file
              has been built in-place or retrieved from the cache.

              The NoCache() method can be used to disable caching of specific files.  This can be
              useful  if  inputs  and/or  outputs  of  some  tool  are  impossible  to predict or
              prohibitively large.

       Clean(targets, files_or_dirs)

       env.Clean(targets, files_or_dirs)
              This specifies a list of files or directories which should be removed whenever  the
              targets  are  specified with the -c command line option.  The specified targets may
              be a list or an individual target.  Multiple calls to Clean() are legal, and create
              new  targets  or  add  files  and  directories  to the clean list for the specified
              targets.

              Multiple files or directories should be specified either as separate  arguments  to
              the Clean() method, or as a list.  Clean() will also accept the return value of any
              of the construction environment Builder methods.  Examples:

              The related NoClean() function overrides calling Clean() for the same  target,  and
              any targets passed to both functions will not be removed by the -c option.

              Examples:

              Clean('foo', ['bar', 'baz'])
              Clean('dist', env.Program('hello', 'hello.c'))
              Clean(['foo', 'bar'], 'something_else_to_clean')

              In   this   example,   installing  the  project  creates  a  subdirectory  for  the
              documentation.  This statement causes the subdirectory to be removed if the project
              is deinstalled.
              Clean(docdir, os.path.join(docdir, projectname))

       env.Clone([key=val, ...])
              Returns  a  separate  copy of a construction environment.  If there are any keyword
              arguments specified, they are added to the returned copy, overwriting any  existing
              values for the keywords.

              Example:

              env2 = env.Clone()
              env3 = env.Clone(CCFLAGS = '-g')

              Additionally,  a  list  of  tools  and  a  toolpath  may  be  specified,  as in the
              Environment constructor:

              def MyTool(env): env['FOO'] = 'bar'
              env4 = env.Clone(tools = ['msvc', MyTool])

              The parse_flags keyword argument is also recognized:

              # create an environment for compiling programs that use wxWidgets
              wx_env = env.Clone(parse_flags = '!wx-config --cflags --cxxflags')

       Command(target, source, action, [key=val, ...])

       env.Command(target, source, action, [key=val, ...])
              Executes a specific action (or list of actions) to build a target  file  or  files.
              This  is  more  convenient  than  defining  a  separate Builder object for a single
              special-case build.

              As a special case, the source_scanner keyword argument can be  used  to  specify  a
              Scanner  object  that  will  be  used  to scan the sources.  (The global DirScanner
              object can be used if any of the sources will be directories that must  be  scanned
              on-disk  for  changes  to  files  that aren't already specified in other Builder of
              function calls.)

              Any other keyword arguments specified override any same-named existing construction
              variables.

              An  action  can be an external command, specified as a string, or a callable Python
              object; see "Action Objects," below, for more complete information.  Also note that
              a  string  specifying  an  external  command  may  be preceded by an @ (at-sign) to
              suppress printing the command in question, or by a - (hyphen) to  ignore  the  exit
              status of the external command.

              Examples:

              env.Command('foo.out', 'foo.in',
                          "$FOO_BUILD < $SOURCES > $TARGET")

              env.Command('bar.out', 'bar.in',
                          ["rm -f $TARGET",
                           "$BAR_BUILD < $SOURCES > $TARGET"],
                          ENV = {'PATH' : '/usr/local/bin/'})

              def rename(env, target, source):
                  import os
                  os.rename('.tmp', str(target[0]))

              env.Command('baz.out', 'baz.in',
                          ["$BAZ_BUILD < $SOURCES > .tmp",
                        rename ])

              Note  that  the  Command()  function  will  usually  assume,  by  default, that the
              specified targets and/or sources are Files, if no other part of  the  configuration
              identifies what type of entry it is.  If necessary, you can explicitly specify that
              targets or source nodes should be treated as directoriese by  using  the  Dir()  or
              env.Dir() functions.

              Examples:

              env.Command('ddd.list', Dir('ddd'), 'ls -l $SOURCE > $TARGET')

              env['DISTDIR'] = 'destination/directory'
              env.Command(env.Dir('$DISTDIR')), None, make_distdir)

              (Also  note that SCons will usually automatically create any directory necessary to
              hold a target file, so you normally don't need to create directories by hand.)

       Configure(env, [custom_tests, conf_dir, log_file, config_h])

       env.Configure([custom_tests, conf_dir, log_file, config_h])
              Creates a Configure object for integrated functionality similar  to  GNU  autoconf.
              See  the  section  "Configure  Contexts,"  below, for a complete explanation of the
              arguments and behavior.

       env.Copy([key=val, ...])
              A now-deprecated synonym for env.Clone().

       env.CVS(repository, module)
              A factory function that returns a Builder object to be used to fetch  source  files
              from  the  specified CVS repository.  The returned Builder is intended to be passed
              to the SourceCode() function.

              This function is deprecated.  For details,  see  the  entry  for  the  SourceCode()
              function.

              The optional specified module will be added to the beginning of all repository path
              names; this can be used, in essence, to strip  initial  directory  names  from  the
              repository  path  names,  so that you only have to replicate part of the repository
              directory hierarchy in your local build directory.

              Examples:

              # Will fetch foo/bar/src.c
              # from /usr/local/CVSROOT/foo/bar/src.c.
              env.SourceCode('.', env.CVS('/usr/local/CVSROOT'))

              # Will fetch bar/src.c
              # from /usr/local/CVSROOT/foo/bar/src.c.
              env.SourceCode('.', env.CVS('/usr/local/CVSROOT', 'foo'))

              # Will fetch src.c
              # from /usr/local/CVSROOT/foo/bar/src.c.
              env.SourceCode('.', env.CVS('/usr/local/CVSROOT', 'foo/bar'))

       Decider(function)

       env.Decider(function)
              Specifies that all up-to-date decisions for targets built through this construction
              environment  will be handled by the specified function.  The function can be one of
              the following strings that specify the type of decision function to be performed:

                 timestamp-newer
                       Specifies that a target shall be considered out of date and rebuilt if the
                       dependency's timestamp is newer than the target file's timestamp.  This is
                       the behavior of the classic Make utility, and make can be used  a  synonym
                       for timestamp-newer.

                 timestamp-match
                       Specifies that a target shall be considered out of date and rebuilt if the
                       dependency's timestamp is different than the timestamp recorded  the  last
                       time  the  target  was  built.  This provides behavior very similar to the
                       classic Make utility (in particular, files are not opened up so that their
                       contents  can  be checksummed) except that the target will also be rebuilt
                       if a dependency file has been  restored  to  a  version  with  an  earlier
                       timestamp, such as can happen when restoring files from backup archives.

                 MD5   Specifies that a target shall be considered out of date and rebuilt if the
                       dependency's content has changed sine the last time the target was  built,
                       as  determined  be performing an MD5 checksum on the dependency's contents
                       and comparing it to the checksum recorded the last  time  the  target  was
                       built.  content can be used as a synonym for MD5.

                 MD5-timestamp
                       Specifies that a target shall be considered out of date and rebuilt if the
                       dependency's content has changed sine the last time the target was  built,
                       except  that  dependencies with a timestamp that matches the last time the
                       target was rebuilt will be assumed to be up-to-date and not rebuilt.  This
                       provides  behavior very similar to the MD5 behavior of always checksumming
                       file contents, with an optimization of not checking the contents of  files
                       whose  timestamps  haven't  changed.   The drawback is that SCons will not
                       detect if a file's content has changed but its timestamp is the  same,  as
                       might happen in an automated script that runs a build, updates a file, and
                       runs the build again, all within a single second.

       Examples:

              # Use exact timestamp matches by default.
              Decider('timestamp-match')

              # Use MD5 content signatures for any targets built
              # with the attached construction environment.
              env.Decider('content')

              In addition to the above already-available functions, the function argument may  be
              an actual Python function that takes the following three arguments:

                 dependency
                        The  Node  (file)  which  should cause the target to be rebuilt if it has
                        "changed" since the last tme target was built.

                 target The Node (file) being built.  In the normal case, this is what should get
                        rebuilt if the dependency has "changed."

                 prev_ni
                        Stored  information  about  the state of the dependency the last time the
                        target  was  built.   This  can  be  consulted  to  match  various   file
                        characteristics such as the timestamp, size, or content signature.

       The  function  should return a True (non-zero) value if the dependency has "changed" since
       the last time the target was built (indicating that the target  should  be  rebuilt),  and
       False  (zero) otherwise (indicating that the target should not be rebuilt).  Note that the
       decision can be made using whatever criteria are appopriate.  Ignoring some or all of  the
       function arguments is perfectly normal.

       Example:

              def my_decider(dependency, target, prev_ni):
                  return not os.path.exists(str(target))

              env.Decider(my_decider)

       Default(targets)

       env.Default(targets)
              This  specifies  a  list  of  default  targets,  which will be built by scons if no
              explicit targets are given on the command line.  Multiple calls  to  Default()  are
              legal, and add to the list of default targets.

              Multiple targets should be specified as separate arguments to the Default() method,
              or as a  list.   Default()  will  also  accept  the  Node  returned  by  any  of  a
              construction environment's builder methods.

              Examples:

              Default('foo', 'bar', 'baz')
              env.Default(['a', 'b', 'c'])
              hello = env.Program('hello', 'hello.c')
              env.Default(hello)

              An  argument  to  Default() of None will clear all default targets.  Later calls to
              Default() will add to the (now empty) default-target list like normal.

              The current list of targets  added  using  the  Default()  function  or  method  is
              available in the DEFAULT_TARGETS list; see below.

       DefaultEnvironment([args])
              Creates  and  returns a default construction environment object.  This construction
              environment is used internally by SCons in order to  execute  many  of  the  global
              functions  in  this  list, and to fetch source files transparently from source code
              management systems.

       Depends(target, dependency)

       env.Depends(target, dependency)
              Specifies  an  explicit  dependency;  the  target  will  be  rebuilt  whenever  the
              dependency  has  changed.  Both the specified target and dependency can be a string
              (usually the path name of a file or directory)  or  Node  objects,  or  a  list  of
              strings  or Node objects (such as returned by a Builder call).  This should only be
              necessary for cases where the dependency is not caught by a Scanner for the file.

              Example:

              env.Depends('foo', 'other-input-file-for-foo')

              mylib = env.Library('mylib.c')
              installed_lib = env.Install('lib', mylib)
              bar = env.Program('bar.c')

              # Arrange for the library to be copied into the installation
              # directory before trying to build the "bar" program.
              # (Note that this is for example only.  A "real" library
              # dependency would normally be configured through the $LIBS
              # and $LIBPATH variables, not using an env.Depends() call.)

              env.Depends(bar, installed_lib)

       env.Dictionary([vars])
              Returns a dictionary object containing copies of all of the construction  variables
              in  the environment.  If there are any variable names specified, only the specified
              construction variables are returned in the dictionary.

              Example:

              dict = env.Dictionary()
              cc_dict = env.Dictionary('CC', 'CCFLAGS', 'CCCOM')

       Dir(name, [directory])

       env.Dir(name, [directory])
              This returns a Directory Node, an object that represents  the  specified  directory
              name.  name can be a relative or absolute path.  directory is an optional directory
              that will be used as the parent directory.   If  no  directory  is  specified,  the
              current script's directory is used as the parent.

              If  name  is a list, SCons returns a list of Dir nodes.  Construction variables are
              expanded in name.

              Directory Nodes can be used anywhere you would supply a string as a directory  name
              to  a Builder method or function.  Directory Nodes have attributes and methods that
              are useful in many situations; see "File and Directory Nodes," below.

       env.Dump([key])
              Returns a pretty printable representation of the environment.  key,  if  not  None,
              should be a string containing the name of the variable of interest.

              This SConstruct:

              env=Environment()
              print env.Dump('CCCOM')

              will print:

              While this SConstruct:

              env=Environment()
              print env.Dump()

              will print:
              { 'AR': 'ar',
                'ARCOM': '$AR $ARFLAGS $TARGET $SOURCES\n$RANLIB $RANLIBFLAGS $TARGET',
                'ARFLAGS': ['r'],
                'AS': 'as',
                'ASCOM': '$AS $ASFLAGS -o $TARGET $SOURCES',
                'ASFLAGS': [],
                ...

       EnsurePythonVersion(major, minor)

       env.EnsurePythonVersion(major, minor)
              Ensure  that  the Python version is at least major.minor.  This function will print
              out an error message and exit SCons with a non-zero exit code if the actual  Python
              version is not late enough.

              Example:

              EnsurePythonVersion(2,2)

       EnsureSConsVersion(major, minor, [revision])

       env.EnsureSConsVersion(major, minor, [revision])
              Ensure that the SCons version is at least major.minor, or major.minor.revision.  if
              revision is specified.  This function will print out  an  error  message  and  exit
              SCons with a non-zero exit code if the actual SCons version is not late enough.

              Examples:

              EnsureSConsVersion(0,14)

              EnsureSConsVersion(0,96,90)

       Environment([key=value, ...])

       env.Environment([key=value, ...])
              Return  a  new  construction  environment  initialized with the specified key=value
              pairs.

       Execute(action, [strfunction, varlist])

       env.Execute(action, [strfunction, varlist])
              Executes an Action object.  The specified action may be an Action object  (see  the
              section  "Action  Objects,"  below, for a complete explanation of the arguments and
              behavior), or it may be a command-line string,  list  of  commands,  or  executable
              Python  function,  each  of  which will be converted into an Action object and then
              executed.  The exit value of the command or return value  of  the  Python  function
              will be returned.

              Note  that scons will print an error message if the executed action fails--that is,
              exits with or returns a non-zero value.  scons  will  not,  however,  automatically
              terminate  the  build if the specified action fails.  If you want the build to stop
              in response to a failed Execute() call, you must explicitly check  for  a  non-zero
              return value:

              Execute(Copy('file.out', 'file.in'))

              if Execute("mkdir sub/dir/ectory"):
                  # The mkdir failed, don't try to build.
                  Exit(1)

       Exit([value])

       env.Exit([value])
              This  tells  scons  to  exit  immediately with the specified value.  A default exit
              value of 0 (zero) is used if no value is specified.

       Export(vars)

       env.Export(vars)
              This tells scons to export a list of variables from the current SConscript file  to
              all  other  SConscript  files.   The  exported  variables  are  kept  in  a  global
              collection, so subsequent calls to Export() will over-write previous  exports  that
              have  the same name.  Multiple variable names can be passed to Export() as separate
              arguments or as a list.  Keyword arguments can be used to provide names  and  their
              values.   A  dictionary  can  be  used  to  map  variables to a different name when
              exported.  Both local variables and global variables can be exported.

              Examples:

              env = Environment()
              # Make env available for all SConscript files to Import().
              Export("env")

              package = 'my_name'
              # Make env and package available for all SConscript files:.
              Export("env", "package")

              # Make env and package available for all SConscript files:
              Export(["env", "package"])

              # Make env available using the name debug:
              Export(debug = env)

              # Make env available using the name debug:
              Export({"debug":env})

              Note that the SConscript() function supports an  exports  argument  that  makes  it
              easier  to  to  export  a variable or set of variables to a single SConscript file.
              See the description of the SConscript() function, below.

       File(name, [directory])

       env.File(name, [directory])
              This returns a File Node, an object that represents the specified file name.   name
              can  be  a relative or absolute path.  directory is an optional directory that will
              be used as the parent directory.

              If name is a list, SCons returns a list of File nodes.  Construction variables  are
              expanded in name.

              File  Nodes  can  be  used  anywhere  you would supply a string as a file name to a
              Builder method or function.  File Nodes have attributes and methods that are useful
              in many situations; see "File and Directory Nodes," below.

       FindFile(file, dirs)

       env.FindFile(file, dirs)
              Search  for  file  in  the path specified by dirs.  dirs may be a list of directory
              names or a single directory name.  In addition to searching for files that exist in
              the  filesystem,  this  function  also searches for derived files that have not yet
              been built.

              Example:

              foo = env.FindFile('foo', ['dir1', 'dir2'])

       FindInstalledFiles()

       env.FindInstalledFiles()
              Returns the list of targets set up by the Install() or InstallAs() builders.

              This function serves as a convenient method to select  the  contents  of  a  binary
              package.

              Example:

              Install( '/bin', [ 'executable_a', 'executable_b' ] )

              # will return the file node list
              # [ '/bin/executable_a', '/bin/executable_b' ]
              FindInstalledFiles()

              Install( '/lib', [ 'some_library' ] )

              # will return the file node list
              # [ '/bin/executable_a', '/bin/executable_b', '/lib/some_library' ]
              FindInstalledFiles()

       FindPathDirs(variable)
              Returns  a  function (actually a callable Python object) intended to be used as the
              path_function of a Scanner object.  The returned object will look up the  specified
              variable  in a construction environment and treat the construction variable's value
              as a list of directory paths that should  be  searched  (like  $CPPPATH,  $LIBPATH,
              etc.).

              Note  that  use  of  FindPathDirs()  is  generally  preferable  to writing your own
              path_function for the following reasons: 1) The  returned  list  will  contain  all
              appropriate  directories  found  in  source trees (when VariantDir() is used) or in
              code repositories (when Repository() or the -Y option are  used).   2)  scons  will
              identify  expansions  of variable that evaluate to the same list of directories as,
              in fact, the same list, and avoid  re-scanning  the  directories  for  files,  when
              possible.

              Example:

              def my_scan(node, env, path, arg):
                  # Code to scan file contents goes here...
                  return include_files

              scanner = Scanner(name = 'myscanner',
                                function = my_scan,
                                path_function = FindPathDirs('MYPATH'))

       FindSourceFiles(node='"."')

       env.FindSourceFiles(node='"."')
              Returns the list of nodes which serve as the source of the built files.  It does so
              by inspecting the dependency tree starting at  the  optional  argument  node  which
              defaults  to the '"."'-node. It will then return all leaves of node.  These are all
              children which have no further children.

              This function is a convenient method to select the contents of a Source Package.

              Example:

              Program( 'src/main_a.c' )
              Program( 'src/main_b.c' )
              Program( 'main_c.c' )

              # returns ['main_c.c', 'src/main_a.c', 'SConstruct', 'src/main_b.c']
              FindSourceFiles()

              # returns ['src/main_b.c', 'src/main_a.c' ]
              FindSourceFiles( 'src' )

              As you can see build support files (SConstruct in the above example) will  also  be
              returned by this function.

       Flatten(sequence)

       env.Flatten(sequence)
              Takes  a  sequence  (that  is,  a  Python  list  or  tuple) that may contain nested
              sequences and returns a flattened list containing all of the individual elements in
              any  sequence.   This  can be helpful for collecting the lists returned by calls to
              Builders; other Builders will automatically flatten lists specified as  input,  but
              direct Python manipulation of these lists does not.

              Examples:

              foo = Object('foo.c')
              bar = Object('bar.c')

              # Because `foo' and `bar' are lists returned by the Object() Builder,
              # `objects' will be a list containing nested lists:
              objects = ['f1.o', foo, 'f2.o', bar, 'f3.o']

              # Passing such a list to another Builder is all right because
              # the Builder will flatten the list automatically:
              Program(source = objects)

              # If you need to manipulate the list directly using Python, you need to
              # call Flatten() yourself, or otherwise handle nested lists:
              for object in Flatten(objects):
                  print str(object)

       GetBuildFailures()
              Returns  a list of exceptions for the actions that failed while attempting to build
              targets.  Each element in the  returned  list  is  a  BuildError  object  with  the
              following attributes that record various aspects of the build failure:

              .node The node that was being built when the build failure occurred.

              .status  The  numeric  exit  status returned by the command or Python function that
              failed when trying to build the specified Node.

              .errstr The SCons error string describing the build  failure.   (This  is  often  a
              generic  message  like "Error 2" to indicate that an executed command exited with a
              status of 2.)

              .filename The name of the file or directory that actually caused the failure.  This
              may  be  different from the .node attribute.  For example, if an attempt to build a
              target named sub/dir/target fails  because  the  sub/dir  directory  could  not  be
              created,  then  the  .node  attribute  will  be  sub/dir/target  but  the .filename
              attribute will be sub/dir.

              .executor The SCons Executor object for the target Node being built.  This  can  be
              used to retrieve the construction environment used for the failed action.

              .action  The  actual  SCons  Action  object that failed.  This will be one specific
              action out of the possible list of actions that would have been executed  to  build
              the target.

              .command  The actual expanded command that was executed and failed, after expansion
              of $TARGET, $SOURCE, and other construction variables.

              Note that the GetBuildFailures() function will always return an  empty  list  until
              any  build  failure  has  occurred, which means that GetBuildFailures() will always
              return an empty list while the  SConscript  files  are  being  read.   Its  primary
              intended  use  is for functions that will be executed before SCons exits by passing
              them to the standard Python atexit.register() function.  Example:

              import atexit

              def print_build_failures():
                  from SCons.Script import GetBuildFailures
                  for bf in GetBuildFailures():
                      print "%s failed: %s" % (bf.node, bf.errstr)

              atexit.register(print_build_failures)

       GetBuildPath(file, [...])

       env.GetBuildPath(file, [...])
              Returns the scons path name (or names) for the  specified  file  (or  files).   The
              specified file or files may be scons Nodes or strings representing path names.

       GetLaunchDir()

       env.GetLaunchDir()
              Returns  the  absolute  path  name  of the directory from which scons was initially
              invoked.  This can be useful when using the -u, -U or -D options, which  internally
              change to the directory in which the SConstruct file is found.

       GetOption(name)

       env.GetOption(name)
              This  function  provides  a  way  to  query the value of SCons options set on scons
              command line (or set using the SetOption() function).  The options supported are:

                 cache_debug
                       which corresponds to --cache-debug;

                 cache_disable
                       which corresponds to --cache-disable;

                 cache_force
                       which corresponds to --cache-force;

                 cache_show
                       which corresponds to --cache-show;

                 clean which corresponds to -c, --clean and --remove;

                 config
                       which corresponds to --config;

                 directory
                       which corresponds to -C and --directory;

                 diskcheck
                       which corresponds to --diskcheck

                 duplicate
                       which corresponds to --duplicate;

                 file  which corresponds to -f, --file, --makefile and --sconstruct;

                 help  which corresponds to -h and --help;

                 ignore_errors
                       which corresponds to --ignore-errors;

                 implicit_cache
                       which corresponds to --implicit-cache;

                 implicit_deps_changed
                       which corresponds to --implicit-deps-changed;

                 implicit_deps_unchanged
                       which corresponds to --implicit-deps-unchanged;

                 interactive
                       which corresponds to --interact and --interactive;

                 keep_going
                       which corresponds to -k and --keep-going;

                 max_drift
                       which corresponds to --max-drift;

                 no_exec
                       which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;

                 no_site_dir
                       which corresponds to --no-site-dir;

                 num_jobs
                       which corresponds to -j and --jobs;

                 profile_file
                       which corresponds to --profile;

                 question
                       which corresponds to -q and --question;

                 random
                       which corresponds to --random;

                 repository
                       which corresponds to -Y, --repository and --srcdir;

                 silent
                       which corresponds to -s, --silent and --quiet;

                 site_dir
                       which corresponds to --site-dir;

                 stack_size
                       which corresponds to --stack-size;

                 taskmastertrace_file
                       which corresponds to --taskmastertrace; and

                 warn  which corresponds to --warn and --warning.

       See the documentation for the corresponding command line object for information about each
       specific option.

       Glob(pattern, [ondisk, source, strings])

       env.Glob(pattern, [ondisk, source, strings])
              Returns  Nodes  (or  strings)  that  match  the  specified pattern, relative to the
              directory of the current SConscript file.   The  env.Glob()  form  performs  string
              substition on pattern and returns whatever matches the resulting expanded pattern.

              The specified pattern uses Unix shell style metacharacters for matching:

                *       matches everything
                ?       matches any single character
                [seq]   matches any character in seq
                [!seq]  matches any char not in seq

              If  the  first  character  of  a  filename is a dot, it must be matched explicitly.
              Character matches do not span directory separators.

              The Glob() knows about repositories (see  the  Repository()  function)  and  source
              directories  (see  the  VariantDir() function) and returns a Node (or string, if so
              configured) in the local (SConscript) directory if matching Node is found  anywhere
              in a corresponding repository or source directory.

              The  ondisk  argument  may be set to False (or any other non-true value) to disable
              the search for matches on disk,  thereby  only  returning  matches  among  already-
              configured  File  or  Dir  Nodes.   The default behavior is to return corresponding
              Nodes for any on-disk matches found.

              The source argument may be set to True (or any equivalent value) to  specify  that,
              when  the  local directory is a VariantDir(), the returned Nodes should be from the
              corresponding source directory, not the local directory.

              The strings argument may be set to True (or  any  equivalent  value)  to  have  the
              Glob()  function  return  strings,  not  Nodes, that represent the matched files or
              directories.  The returned strings will  be  relative  to  the  local  (SConscript)
              directory.  (Note that This may make it easier to perform arbitrary manipulation of
              file names, but if the returned strings are passed to a different SConscript  file,
              any  Node  translation  will be relative to the other SConscript directory, not the
              original SConscript directory.)

              Examples:

              Program('foo', Glob('*.c'))
              Zip('/tmp/everything', Glob('.??*') + Glob('*'))

       Help(text)

       env.Help(text)
              This specifies help text to be printed if the -h argument is given  to  scons.   If
              Help()  is  called  multiple times, the text is appended together in the order that
              Help() is called.

       Ignore(target, dependency)

       env.Ignore(target, dependency)
              The specified dependency file(s) will  be  ignored  when  deciding  if  the  target
              file(s) need to be rebuilt.

              You  can  also use Ignore() to remove a target from the default build.  In order to
              do this you must specify the directory the target will be built in as  the  target,
              and the file you want to skip building as the dependency.

              Note  that  this  will  only remove the dependencies listed from the files built by
              default.  It will still be built if that dependency is  needed  by  another  object
              being built.  See the third and forth examples below.

              Examples:

              env.Ignore('foo', 'foo.c')
              env.Ignore('bar', ['bar1.h', 'bar2.h'])
              env.Ignore('.','foobar.obj')
              env.Ignore('bar','bar/foobar.obj')

       Import(vars)

       env.Import(vars)
              This  tells  scons  to import a list of variables into the current SConscript file.
              This will import variables that were exported  with  Export()  or  in  the  exports
              argument  to  SConscript().   Variables  exported  by SConscript() have precedence.
              Multiple variable names can be passed to Import() as separate  arguments  or  as  a
              list. The variable "*" can be used to import all variables.

              Examples:

              Import("env")
              Import("env", "variable")
              Import(["env", "variable"])
              Import("*")

       Literal(string)

       env.Literal(string)
              The  specified  string  will be preserved as-is and not have construction variables
              expanded.

       Local(targets)

       env.Local(targets)
              The specified targets will have copies made in the local tree, even if  an  already
              up-to-date  copy  exists  in  a  repository.   Returns a list of the target Node or
              Nodes.

       env.MergeFlags(arg, [unique])
              Merges the specified arg values  to  the  construction  environment's  construction
              variables.   If  the  arg  argument  is not a dictionary, it is converted to one by
              calling env.ParseFlags() on the argument before the values are merged.   Note  that
              arg must be a single value, so multiple strings must be passed in as a list, not as
              separate arguments to env.MergeFlags().

              By default, duplicate values are eliminated; you can, however, specify unique=0  to
              allow  duplicate  values  to  be  added.   When  eliminating  duplicate values, any
              construction variables that end with the string  PATH  keep  the  left-most  unique
              value.  All other construction variables keep the right-most unique value.

              Examples:

              # Add an optimization flag to $CCFLAGS.
              env.MergeFlags('-O3')

              # Combine the flags returned from running pkg-config with an optimization
              # flag and merge the result into the construction variables.
              env.MergeFlags(['!pkg-config gtk+-2.0 --cflags', '-O3'])

              # Combine an optimization flag with the flags returned from running pkg-config
              # twice and merge the result into the construction variables.
              env.MergeFlags(['-O3',
                             '!pkg-config gtk+-2.0 --cflags --libs',
                             '!pkg-config libpng12 --cflags --libs'])

       NoCache(target, ...)

       env.NoCache(target, ...)
              Specifies a list of files which should not be cached whenever the CacheDir() method
              has been activated.  The specified targets may be a list or an individual target.

              Multiple files should be specified either as separate arguments  to  the  NoCache()
              method,  or  as  a list.  NoCache() will also accept the return value of any of the
              construction environment Builder methods.

              Calling NoCache() on directories and  other  non-File  Node  types  has  no  effect
              because only File Nodes are cached.

              Examples:

              NoCache('foo.elf')
              NoCache(env.Program('hello', 'hello.c'))

       NoClean(target, ...)

       env.NoClean(target, ...)
              Specifies  a  list of files or directories which should not be removed whenever the
              targets (or their dependencies) are specified with the -c command line option.  The
              specified  targets  may  be  a  list  or  an  individual target.  Multiple calls to
              NoClean() are legal, and prevent each specified target from being removed by  calls
              to the -c option.

              Multiple  files  or directories should be specified either as separate arguments to
              the NoClean() method, or as a list.  NoClean() will also accept the return value of
              any of the construction environment Builder methods.

              Calling  NoClean()  for a target overrides calling Clean() for the same target, and
              any targets passed to both functions will not be removed by the -c option.

              Examples:

              NoClean('foo.elf')
              NoClean(env.Program('hello', 'hello.c'))

       env.ParseConfig(command, [function, unique])
              Calls the specified function to modify the environment as specified by  the  output
              of  command.  The default function is env.MergeFlags(), which expects the output of
              a typical *-config command (for example, gtk-config) and adds the  options  to  the
              appropriate  construction variables.  By default, duplicate values are not added to
              any construction variables; you can specify unique=0 to allow duplicate  values  to
              be added.

              Interpreted options and the construction variables they affect are as specified for
              the  env.ParseFlags()  method  (which  this  method  calls).   See  that   method's
              description, below, for a table of options and construction variables.

       ParseDepends(filename, [must_exist, only_one])

       env.ParseDepends(filename, [must_exist, only_one])
              Parses  the  contents  of  the  specified filename as a list of dependencies in the
              style of Make or mkdep, and explicitly establishes all of the listed dependencies.

              By default, it is not an error if the  specified  filename  does  not  exist.   The
              optional  must_exist argument may be set to a non-zero value to have scons throw an
              exception and generate an error if  the  file  does  not  exist,  or  is  otherwise
              inaccessible.

              The  optional only_one argument may be set to a non-zero value to have scons thrown
              an exception and generate an error if the file contains dependency information  for
              more  than one target.  This can provide a small sanity check for files intended to
              be generated by, for example, the gcc -M flag, which should  typically  only  write
              dependency information for one output file into a corresponding .d file.

              The  filename  and  all of the files listed therein will be interpreted relative to
              the directory of the SConscript file which calls the ParseDepends() function.

       env.ParseFlags(flags, ...)
              Parses one or more strings containing  typical  command-line  flags  for  GCC  tool
              chains and returns a dictionary with the flag values separated into the appropriate
              SCons  construction  variables.   This  is  intended  as   a   companion   to   the
              env.MergeFlags() method, but allows for the values in the returned dictionary to be
              modified, if necessary, before merging  them  into  the  construction  environment.
              (Note  that  env.MergeFlags()  will  call  this  method  if  its  argument is not a
              dictionary, so it is usually not necessary to call env.ParseFlags() directly unless
              you want to manipulate the values.)

              If  the  first  character in any string is an exclamation mark (!), the rest of the
              string is executed as a command, and the output from the command is parsed  as  GCC
              tool chain command-line flags and added to the resulting dictionary.

              Flag values are translated accordig to the prefix found, and added to the following
              construction variables:

              -arch               CCFLAGS, LINKFLAGS
              -D                  CPPDEFINES
              -framework          FRAMEWORKS
              -frameworkdir=      FRAMEWORKPATH
              -include            CCFLAGS
              -isysroot           CCFLAGS, LINKFLAGS
              -I                  CPPPATH
              -l                  LIBS
              -L                  LIBPATH
              -mno-cygwin         CCFLAGS, LINKFLAGS
              -mwindows           LINKFLAGS
              -pthread            CCFLAGS, LINKFLAGS
              -std=               CFLAGS
              -Wa,                ASFLAGS, CCFLAGS
              -Wl,-rpath=         RPATH
              -Wl,-R,             RPATH
              -Wl,-R              RPATH
              -Wl,                LINKFLAGS
              -Wp,                CPPFLAGS
              -                   CCFLAGS
              +                   CCFLAGS, LINKFLAGS

              Any other strings not associated with options  are  assumed  to  be  the  names  of
              libraries and added to the $LIBS construction variable.

              Examples (all of which produce the same result):

              dict = env.ParseFlags('-O2 -Dfoo -Dbar=1')
              dict = env.ParseFlags('-O2', '-Dfoo', '-Dbar=1')
              dict = env.ParseFlags(['-O2', '-Dfoo -Dbar=1'])
              dict = env.ParseFlags('-O2', '!echo -Dfoo -Dbar=1')

       env.Perforce()
              A  factory  function that returns a Builder object to be used to fetch source files
              from the Perforce source code management system.  The returned Builder is  intended
              to be passed to the SourceCode() function.

              This  function  is  deprecated.   For  details,  see the entry for the SourceCode()
              function.

              Example:

              env.SourceCode('.', env.Perforce())

              Perforce uses a  number  of  external  environment  variables  for  its  operation.
              Consequently,  this  function adds the following variables from the user's external
              environment to the construction environment's ENV dictionary: P4CHARSET,  P4CLIENT,
              P4LANGUAGE, P4PASSWD, P4PORT, P4USER, SystemRoot, USER, and USERNAME.

       Platform(string)
              The  Platform()  form  returns  a  callable object that can be used to initialize a
              construction environment using the platform keyword of the Environment() function.

              Example:

              env = Environment(platform = Platform('win32'))

              The env.Platform() form applies the callable  object  for  the  specified  platform
              string to the environment through which the method was called.

              env.Platform('posix')

              Note that the win32 platform adds the SystemDrive and SystemRoot variables from the
              user's external environment to  the  construction  environment's  $ENV  dictionary.
              This  is  so  that  any  executed  commands  that use sockets to connect with other
              systems (such as fetching source files from external CVS repository  specifications
              like  :pserver:anonymous@cvs.sourceforge.net:/cvsroot/scons)  will  work on Windows
              systems.

       Precious(target, ...)

       env.Precious(target, ...)
              Marks each given target as precious so it is not  deleted  before  it  is  rebuilt.
              Normally scons deletes a target before building it.  Multiple targets can be passed
              in to a single call to Precious().

       env.Prepend(key=val, [...])
              Appends the specified keyword arguments to the beginning of construction  variables
              in  the  environment.   If the Environment does not have the specified construction
              variable, it is simply added to the environment.  If the values of the construction
              variable  and  the  keyword argument are the same type, then the two values will be
              simply added together.  Otherwise, the construction variable and the value  of  the
              keyword argument are both coerced to lists, and the lists are added together.  (See
              also the Append method, above.)

              Example:

              env.Prepend(CCFLAGS = '-g ', FOO = ['foo.yyy'])

       env.PrependENVPath(name, newpath, [envname, sep, delete_existing])
              This appends new path  elements  to  the  given  path  in  the  specified  external
              environment  ($ENV  by  default).   This  will  only  add  any particular path once
              (leaving the first one it encounters  and  ignoring  the  rest,  to  preserve  path
              order),  and  to help assure this, will normalize all paths (using os.path.normpath
              and os.path.normcase).  This can also handle the case  where  the  given  old  path
              variable  is  a  list  instead  of  a string, in which case a list will be returned
              instead of a string.

              If delete_existing is 0, then adding a path that already exists will not move it to
              the beginning; it will stay where it is in the list.

              Example:

              print 'before:',env['ENV']['INCLUDE']
              include_path = '/foo/bar:/foo'
              env.PrependENVPath('INCLUDE', include_path)
              print 'after:',env['ENV']['INCLUDE']

              The above example will print:

              before: /biz:/foo
              after: /foo/bar:/foo:/biz

       env.PrependUnique(key=val, delete_existing=0, [...])
              Appends  the specified keyword arguments to the beginning of construction variables
              in the environment.  If the Environment does not have  the  specified  construction
              variable,  it  is  simply  added  to the environment.  If the construction variable
              being appended to  is  a  list,  then  any  value(s)  that  already  exist  in  the
              construction   variable  will  not  be  added  again  to  the  list.   However,  if
              delete_existing is 1, existing matching  values  are  removed  first,  so  existing
              values in the arg list move to the front of the list.

              Example:

              env.PrependUnique(CCFLAGS = '-g', FOO = ['foo.yyy'])

       Progress(callable, [interval])

       Progress(string, [interval, file, overwrite])

       Progress(list_of_strings, [interval, file, overwrite])
              Allows  SCons  to  show  progress  made  during the build by displaying a string or
              calling a function while evaluating Nodes (e.g. files).

              If the first specified argument is a Python callable (a function or an object  that
              has  a  __call__() method), the function will be called once every interval times a
              Node is evaluated.  The callable will be passed the  evaluated  Node  as  its  only
              argument.   (For  future compatibility, it's a good idea to also add *args and **kw
              as arguments to your function or method.  This will prevent the code from  breaking
              if  SCons ever changes the interface to call the function with additional arguments
              in the future.)

              An example of a simple custom progress function that prints a string containing the
              Node name every 10 Nodes:

              def my_progress_function(node, *args, **kw):
                  print 'Evaluating node %s!' % node
              Progress(my_progress_function, interval=10)

              A more complicated example of a custom progress display object t(atcarriageareturn)
              containing a count every 100 evaluated Nodes.  Note the use of
              at the end so that the string will overwrite itself on a display:

              import sys
              class ProgressCounter(object):
                  count = 0
                  def __call__(self, node, *args, **kw):
                      self.count += 100
                      sys.stderr.write('Evaluated %s nodes\r' % self.count)
              Progress(ProgressCounter(), interval=100)

              If  the  first  argument Progress() is a string, the string will be displayed every
              interval evaluated Nodes.  The default is to print the string on  standard  output;
              an alternate output stream may be specified with the file= argument.  The following
              will print a series of dots on the error output, one dot for  every  100  evaluated
              Nodes:

              import sys
              Progress('.', interval=100, file=sys.stderr)

              If the string contains the verbatim substring $TARGET, it will be replaced with the
              Node.  Note that, for performance reasons, this is not  a  regular  SCons  variable
              substition,  so you can not use other variables or use curly b(carriagehreturn)wito
              example will print the name of every evaluated Node, using a
              cause  each  line  to  overwritten  by  the  next  line, and the overwrite= keyword
              argument to make sure the previously-printed file name is  overwritten  with  blank
              spaces:

              import sys
              Progress('$TARGET\r', overwrite=True)

              If  the  first argument to Progress() is a list of strings, then each string in the
              list will be displayed in rotating fashion every interval  evaluated  Nodes.   This
              can be used to implement a "spinner" on the user's screen as follows:

              Progress(['-\r', '\\\r', '|\r', '/\r'], interval=5)

       env.RCS()
              A  factory  function that returns a Builder object to be used to fetch source files
              from RCS.  The returned Builder is  intended  to  be  passed  to  the  SourceCode()
              function:

              This  function  is  deprecated.   For  details,  see the entry for the SourceCode()
              function.

              Examples:

              env.SourceCode('.', env.RCS())

              Note that scons will fetch source files from RCS subdirectories  automatically,  so
              configuring  RCS  as  demonstrated in the above example should only be necessary if
              you are fetching from RCS,v files in the same directory as the source files, or  if
              you need to explicitly specify RCS for a specific subdirectory.

       env.Replace(key=val, [...])
              Replaces  construction  variables  in  the  Environment  with the specified keyword
              arguments.

              Example:

              env.Replace(CCFLAGS = '-g', FOO = 'foo.xxx')

       Repository(directory)

       env.Repository(directory)
              Specifies that directory is a repository to be searched for files.  Multiple  calls
              to  Repository() are legal, and each one adds to the list of repositories that will
              be searched.

              To scons, a repository is a copy of the source tree, from the  top-level  directory
              on  down, which may contain both source files and derived files that can be used to
              build targets in the local source tree.  The canonical example would be an official
              source tree maintained by an integrator.  If the repository contains derived files,
              then the derived files should have been built using scons, so that  the  repository
              contains  the  necessary signature information to allow scons to figure out when it
              is appropriate to use the repository copy of a derived file,  instead  of  building
              one locally.

              Note  that if an up-to-date derived file already exists in a repository, scons will
              not make a copy in the local directory tree.  In order to guarantee  that  a  local
              copy will be made, use the Local() method.

       Requires(target, prerequisite)

       env.Requires(target, prerequisite)
              Specifies  an  order-only relationship between the specified target file(s) and the
              specified prerequisite file(s).  The prerequisite file(s)  will  be  (re)built,  if
              necessary, before the target file(s), but the target file(s) do not actually depend
              on the prerequisites and will  not  be  rebuilt  simply  because  the  prerequisite
              file(s) change.

              Example:

              env.Requires('foo', 'file-that-must-be-built-before-foo')

       Return([vars..., stop=])
              By  default,  this  stops processing the current SConscript file and returns to the
              calling SConscript file the values of  the  variables  named  in  the  vars  string
              arguments.   Multiple  strings  contaning variable names may be passed to Return().
              Any strings that contain white space

              The optional stop= keyword argument may  be  set  to  a  false  value  to  continue
              processing  the  rest of the SConscript file after the Return() call.  This was the
              default behavior prior to SCons 0.98.  However, the values returned are  still  the
              values of the variables in the named vars at the point Return() is called.

              Examples:

              # Returns without returning a value.
              Return()

              # Returns the value of the 'foo' Python variable.
              Return("foo")

              # Returns the values of the Python variables 'foo' and 'bar'.
              Return("foo", "bar")

              # Returns the values of Python variables 'val1' and 'val2'.
              Return('val1 val2')

       Scanner(function,  [argument,  keys,  path_function, node_class, node_factory, scan_check,
       recursive])

       env.Scanner(function,   [argument,   keys,   path_function,   node_class,    node_factory,
       scan_check, recursive])
              Creates  a  Scanner  object  for  the specified function.  See the section "Scanner
              Objects," below, for a complete explanation of the arguments and behavior.

       env.SCCS()
              A factory function that returns a Builder object to be used to fetch  source  files
              from  SCCS.   The  returned  Builder  is  intended to be passed to the SourceCode()
              function.

              Example:

              env.SourceCode('.', env.SCCS())

              Note that scons will fetch source files from SCCS subdirectories automatically,  so
              configuring  SCCS  as demonstrated in the above example should only be necessary if
              you are fetching from s.SCCS files in the same directory as the source files, or if
              you need to explicitly specify SCCS for a specific subdirectory.

       SConscript(scripts, [exports, variant_dir, duplicate])

       env.SConscript(scripts, [exports, variant_dir, duplicate])

       SConscript(dirs=subdirs, [name=script, exports, variant_dir, duplicate])

       env.SConscript(dirs=subdirs, [name=script, exports, variant_dir, duplicate])
              This  tells  scons  to  execute  one  or more subsidiary SConscript (configuration)
              files.  Any variables returned by a called script using Return() will  be  returned
              by the call to SConscript().  There are two ways to call the SConscript() function.

              The  first  way  you  can  call  SConscript()  is to explicitly specify one or more
              scripts as the first argument.  A single script  may  be  specified  as  a  string;
              multiple  scripts must be specified as a list (either explicitly or as created by a
              function like Split()).  Examples:
              SConscript('SConscript')      # run SConscript in the current directory
              SConscript('src/SConscript')  # run SConscript in the src directory
              SConscript(['src/SConscript', 'doc/SConscript'])
              config = SConscript('MyConfig.py')

              The second way you can call SConscript() is to specify  a  list  of  (sub)directory
              names  as  a  dirs=subdirs keyword argument.  In this case, scons will, by default,
              execute a subsidiary configuration file named SConscript in each of  the  specified
              directories.  You may specify a name other than SConscript by supplying an optional
              name=script keyword argument.  The first three examples below have the same  effect
              as the first three examples above:
              SConscript(dirs='.')      # run SConscript in the current directory
              SConscript(dirs='src')    # run SConscript in the src directory
              SConscript(dirs=['src', 'doc'])
              SConscript(dirs=['sub1', 'sub2'], name='MySConscript')

              The  optional exports argument provides a list of variable names or a dictionary of
              named values to export to the script(s).  These variables are locally exported only
              to  the specified script(s), and do not affect the global pool of variables used by
              the Export() function.  The subsidiary script(s) must use the Import() function  to
              import the variables.  Examples:
              foo = SConscript('sub/SConscript', exports='env')
              SConscript('dir/SConscript', exports=['env', 'variable'])
              SConscript(dirs='subdir', exports='env variable')
              SConscript(dirs=['one', 'two', 'three'], exports='shared_info')

              If  the optional variant_dir argument is present, it causes an effect equivalent to
              the VariantDir() method described below.   (If  variant_dir  is  not  present,  the
              duplicate  argument  is ignored.)  The variant_dir argument is interpreted relative
              to the directory of the calling  SConscript  file.   See  the  description  of  the
              VariantDir() function below for additional details and restrictions.

              If  variant_dir  is  present,  the  source  directory is the directory in which the
              SConscript file resides and the SConscript file is evaluated as if it were  in  the
              variant_dir directory:
              SConscript('src/SConscript', variant_dir = 'build')

              is equivalent to

              VariantDir('build', 'src')
              SConscript('build/SConscript')

              This later paradigm is often used when the sources are in the same directory as the
              SConstruct:

              SConscript('SConscript', variant_dir = 'build')

              is equivalent to

              VariantDir('build', '.')
              SConscript('build/SConscript')

              Here are some composite examples:

              # collect the configuration information and use it to build src and doc
              shared_info = SConscript('MyConfig.py')
              SConscript('src/SConscript', exports='shared_info')
              SConscript('doc/SConscript', exports='shared_info')

              # build debugging and production versions.  SConscript
              # can use Dir('.').path to determine variant.
              SConscript('SConscript', variant_dir='debug', duplicate=0)
              SConscript('SConscript', variant_dir='prod', duplicate=0)

              # build debugging and production versions.  SConscript
              # is passed flags to use.
              opts = { 'CPPDEFINES' : ['DEBUG'], 'CCFLAGS' : '-pgdb' }
              SConscript('SConscript', variant_dir='debug', duplicate=0, exports=opts)
              opts = { 'CPPDEFINES' : ['NODEBUG'], 'CCFLAGS' : '-O' }
              SConscript('SConscript', variant_dir='prod', duplicate=0, exports=opts)

              # build common documentation and compile for different architectures
              SConscript('doc/SConscript', variant_dir='build/doc', duplicate=0)
              SConscript('src/SConscript', variant_dir='build/x86', duplicate=0)
              SConscript('src/SConscript', variant_dir='build/ppc', duplicate=0)

       SConscriptChdir(value)

       env.SConscriptChdir(value)
              By default, scons changes its working directory to  the  directory  in  which  each
              subsidiary  SConscript  file  lives.   This  behavior may be disabled by specifying
              either:

              SConscriptChdir(0)
              env.SConscriptChdir(0)

              in which case scons  will  stay  in  the  top-level  directory  while  reading  all
              SConscript files.  (This may be necessary when building from repositories, when all
              the directories in which SConscript files may  be  found  don't  necessarily  exist
              locally.)   You  may  enable  and disable this ability by calling SConscriptChdir()
              multiple times.

              Example:

              env = Environment()
              SConscriptChdir(0)
              SConscript('foo/SConscript')  # will not chdir to foo
              env.SConscriptChdir(1)
              SConscript('bar/SConscript')  # will chdir to bar

       SConsignFile([file, dbm_module])

       env.SConsignFile([file, dbm_module])
              This tells scons to store all file signatures in the specified database  file.   If
              the  file  name is omitted, .sconsign is used by default.  (The actual file name(s)
              stored on disk may have an appropriated suffix appended  by  the  dbm_module.)   If
              file  is not an absolute path name, the file is placed in the same directory as the
              top-level SConstruct file.

              If file is None, then scons will store file signatures in a separate .sconsign file
              in each directory, not in one global database file.  (This was the default behavior
              prior to SCons 0.96.91 and 0.97.)

              The optional dbm_module argument can be  used  to  specify  which  Python  database
              module  The default is to use a custom SCons.dblite module that uses pickled Python
              data structures, and which works on all Python versions.

              Examples:

              # Explicitly stores signatures in ".sconsign.dblite"
              # in the top-level SConstruct directory (the
              # default behavior).
              SConsignFile()

              # Stores signatures in the file "etc/scons-signatures"
              # relative to the top-level SConstruct directory.
              SConsignFile("etc/scons-signatures")

              # Stores signatures in the specified absolute file name.
              SConsignFile("/home/me/SCons/signatures")

              # Stores signatures in a separate .sconsign file
              # in each directory.
              SConsignFile(None)

       env.SetDefault(key=val, [...])
              Sets construction variables to default values specified with the keyword  arguments
              if  (and  only if) the variables are not already set.  The following statements are
              equivalent:

              env.SetDefault(FOO = 'foo')

              if 'FOO' not in env: env['FOO'] = 'foo'

       SetOption(name, value)

       env.SetOption(name, value)
              This function provides a way to set a select  subset  of  the  scons  command  line
              options from a SConscript file. The options supported are:

                 clean which corresponds to -c, --clean and --remove;

                 duplicate
                       which corresponds to --duplicate;

                 help  which corresponds to -h and --help;

                 implicit_cache
                       which corresponds to --implicit-cache;

                 max_drift
                       which corresponds to --max-drift;

                 no_exec
                       which corresponds to -n, --no-exec, --just-print, --dry-run and --recon;

                 num_jobs
                       which corresponds to -j and --jobs;

                 random
                       which corresponds to --random; and

                 stack_size
                       which corresponds to --stack-size.

       See the documentation for the corresponding command line object for information about each
       specific option.

       Example:

              SetOption('max_drift', 1)

       SideEffect(side_effect, target)

       env.SideEffect(side_effect, target)
              Declares side_effect as a side effect of building  target.   Both  side_effect  and
              target  can be a list, a file name, or a node.  A side effect is a target file that
              is created or updated as a side effect of building other targets.  For  example,  a
              Windows  PDB  file  is  created  as  a side effect of building the .obj files for a
              static library, and various log files  are  created  updated  as  side  effects  of
              various  TeX  commands.   If  a target is a side effect of multiple build commands,
              scons  will  ensure  that  only  one  set  of  commands  is  executed  at  a  time.
              Consequently,  you  only  need  to use this method for side-effect targets that are
              built as a result of multiple build commands.

              Because multiple build commands may update the same side effect  file,  by  default
              the  side_effect  target is not automatically removed when the target is removed by
              the -c option.  (Note, however, that the side_effect might be removed  as  part  of
              cleaning  the  directory  in  which  it  lives.)   If  you  want  to  make sure the
              side_effect is cleaned whenever a specific target is cleaned, you must specify this
              explicitly with the Clean() or env.Clean() function.

       SourceCode(entries, builder)

       env.SourceCode(entries, builder)
              This  function  and  its  associate  factory functions are deprecated.  There is no
              replacement.  The intended use was to keep a local tree in sync  with  an  archive,
              but  in  actuality  the function only causes the archive to be fetched on the first
              run.  Synchronizing with the archive is best done external to &SCons;.

              Arrange for non-existent source files to be fetched from a source  code  management
              system using the specified builder.  The specified entries may be a Node, string or
              list of both, and may represent either individual source files  or  directories  in
              which source files can be found.

              For  any non-existent source files, scons will search up the directory tree and use
              the first SourceCode() builder it finds.  The specified builder  may  be  None,  in
              which  case  scons  will  not use a builder to fetch source files for the specified
              entries, even if a SourceCode() builder has been specified for a  directory  higher
              up the tree.

              scons  will,  by  default,  fetch  files  from  SCCS  or RCS subdirectories without
              explicit configuration.  This takes some extra processing time to  search  for  the
              necessary source code management files on disk.  You can avoid these extra searches
              and speed up your build a little by disabling these searches as follows:

              env.SourceCode('.', None)

              Note that if the specified builder is one you create  by  hand,  it  must  have  an
              associated construction environment to use when fetching a source file.

              scons  provides  a set of canned factory functions that return appropriate Builders
              for  various  popular  source  code  management  systems.   Canonical  examples  of
              invocation include:

              env.SourceCode('.', env.BitKeeper('/usr/local/BKsources'))
              env.SourceCode('src', env.CVS('/usr/local/CVSROOT'))
              env.SourceCode('/', env.RCS())
              env.SourceCode(['f1.c', 'f2.c'], env.SCCS())
              env.SourceCode('no_source.c', None)

       SourceSignatures(type)

       env.SourceSignatures(type)
              Note:   Although  it  is  not  yet  officially  deprecated, use of this function is
              discouraged.  See the Decider() function for a more  flexible  and  straightforward
              way to configure SCons' decision-making.

              The  SourceSignatures() function tells scons how to decide if a source file (a file
              that is not built from any other files) has changed since the last time it was used
              to build a particular target file.  Legal values are MD5 or timestamp.

              If  the  environment method is used, the specified type of source signature is only
              used when deciding whether targets built with that environment  are  up-to-date  or
              must  be  rebuilt.   If  the  global function is used, the specified type of source
              signature becomes the default used for all decisions about whether targets are  up-
              to-date.

              MD5  means  scons decides that a source file has changed if the MD5 checksum of its
              contents has changed since the last time it was used to rebuild a particular target
              file.

              timestamp  means  scons  decides  that  a  source file has changed if its timestamp
              (modification time) has changed since the last  time  it  was  used  to  rebuild  a
              particular  target  file.   (Note  that although this is similar to the behavior of
              Make, by default it will also rebuild if the dependency is older than the last time
              it was used to rebuild the target file.)

              There is no different between the two behaviors for Python Value() node objects.

              MD5  signatures  take  longer  to  compute,  but  are  more accurate than timestamp
              signatures.  The default value is MD5.

              Note that the default  TargetSignatures()  setting  (see  below)  is  to  use  this
              SourceSignatures() setting for any target files that are used to build other target
              files.  Consequently, changing the value of SourceSignatures()  will,  by  default,
              affect  the up-to-date decision for all files in the build (or all files built with
              a specific construction environment when env.SourceSignatures() is used).

       Split(arg)

       env.Split(arg)
              Returns a list of file names or other objects.  If arg is  a  string,  it  will  be
              split  on  strings of white-space characters within the string, making it easier to
              write long lists of file names.  If arg  is  already  a  list,  the  list  will  be
              returned  untouched.   If arg is any other type of object, it will be returned as a
              list containing just the object.

              Example:

              files = Split("f1.c f2.c f3.c")
              files = env.Split("f4.c f5.c f6.c")
              files = Split("""
                   f7.c
                   f8.c
                   f9.c
              """)

       env.subst(input, [raw, target, source, conv])
              Performs construction variable interpolation on the specified  string  or  sequence
              argument input.

              By  default,  leading or trailing white space will be removed from the result.  and
              all sequences of white space will  be  compressed  to  a  single  space  character.
              Additionally,  any $( and $) character sequences will be stripped from the returned
              string, The optional raw argument may be set to 1 if you  want  to  preserve  white
              space  and  $(-$) sequences.  The raw argument may be set to 2 if you want to strip
              all characters between any $( and $) pairs (as is done for signature calculation).

              If the input is a sequence (list or tuple), the individual elements of the sequence
              will be expanded, and the results will be returned as a list.

              The optional target and source keyword arguments must be set to lists of target and
              source nodes, respectively, if you want the $TARGET, $TARGETS, $SOURCE and $SOURCES
              to  be  available  for  expansion.   This  is  usually necessary if you are calling
              env.subst() from within a Python function used as an SCons action.

              Returned  string  values  or  sequence  elements  are  converted  to  their  string
              representation  by  default.   The  optional conv argument may specify a conversion
              function that will be used in place of the  default.   For  example,  if  you  want
              Python  objects  (including  SCons Nodes) to be returned as Python objects, you can
              use the Python lambda idiom to pass in an unnamed function that simply returns  its
              unconverted argument.

              Example:

              print env.subst("The C compiler is: $CC")

              def compile(target, source, env):
                  sourceDir = env.subst("${SOURCE.srcdir}",
                                        target=target,
                                        source=source)

              source_nodes = env.subst('$EXPAND_TO_NODELIST',
                                       conv=lambda x: x)

       Tag(node, tags)
              Annotates  file or directory Nodes with information about how the Package() Builder
              should package those files or directories.  All tags are optional.

              Examples:

              # makes sure the built library will be installed with 0644 file
              # access mode
              Tag( Library( 'lib.c' ), UNIX_ATTR="0644" )

              # marks file2.txt to be a documentation file
              Tag( 'file2.txt', DOC )

       TargetSignatures(type)

       env.TargetSignatures(type)
              Note:  Although it is not yet  officially  deprecated,  use  of  this  function  is
              discouraged.   See  the  Decider() function for a more flexible and straightforward
              way to configure SCons' decision-making.

              The TargetSignatures() function tells scons how to decide if a target file (a  file
              that  is built from any other files) has changed since the last time it was used to
              build some other target file.  Legal values are  build;  content  (or  its  synonym
              MD5); timestamp; or source.

              If  the  environment method is used, the specified type of target signature is only
              used for targets built with that environment.  If the global function is used,  the
              specified  type  of  signature  becomes  the default used for all target files that
              don't have an explicit target signature type specified for their environments.

              content (or its synonym MD5) means scons decides that a target file has changed  if
              the  MD5  checksum  of  its contents has changed since the last time it was used to
              rebuild some other target file.  This means scons will open up MD5 sum the contents
              of  target  files  after  they're  built,  and  may decide that it does not need to
              rebuild "downstream" target files if a file  was  rebuilt  with  exactly  the  same
              contents as the last time.

              timestamp  means  scons  decides  that  a  target file has changed if its timestamp
              (modification time) has changed since the last time it was  used  to  rebuild  some
              other target file.  (Note that although this is similar to the behavior of Make, by
              default it will also rebuild if the dependency is older than the last time  it  was
              used to rebuild the target file.)

              source  means  scons  decides  that  a  target file has changed as specified by the
              corresponding SourceSignatures() setting (MD5 or timestamp).  This means that scons
              will treat all input files to a target the same way, regardless of whether they are
              source files or have been built from other files.

              build means scons decides that a target file has changed if it has been rebuilt  in
              this  invocation  or  if  its content or timestamp have changed as specified by the
              corresponding SourceSignatures()  setting.   This  "propagates"  the  status  of  a
              rebuilt  file  so that other "downstream" target files will always be rebuilt, even
              if the contents or the timestamp have not changed.

              build signatures are fastest because content (or MD5)  signatures  take  longer  to
              compute,  but  are  more  accurate  than  timestamp  signatures,  and  can  prevent
              unnecessary "downstream" rebuilds when a target file is rebuilt to the  exact  same
              contents  as  the  previous build.  The source setting provides the most consistent
              behavior when other target files may be rebuilt from both source and  target  input
              files.  The default value is source.

              Because  the  default  setting  is  source,  using  SourceSignatures() is generally
              preferable  to  TargetSignatures(),  so  that  the  up-to-date  decision  will   be
              consistent  for  all  files  (or  all  files  built  with  a  specific construction
              environment).  Use of TargetSignatures() provides specific control  for  how  built
              target files affect their "downstream" dependencies.

       Tool(string, [toolpath, **kw])

       env.Tool(string, [toolpath, **kw])
              The  Tool()  form  of  the  function  returns a callable object that can be used to
              initialize a construction environment using the tools keyword of the  Environment()
              method.   The  object may be called with a construction environment as an argument,
              in which case the object will add  the  necessary  variables  to  the  construction
              environment  and  the  name  of  the  tool will be added to the $TOOLS construction
              variable.

              Additional keyword arguments are passed to the tool's generate() method.

              Examples:

              env = Environment(tools = [ Tool('msvc') ])

              env = Environment()
              t = Tool('msvc')
              t(env)  # adds 'msvc' to the TOOLS variable
              u = Tool('opengl', toolpath = ['tools'])
              u(env)  # adds 'opengl' to the TOOLS variable

              The env.Tool() form of the function applies the callable object for  the  specified
              tool string to the environment through which the method was called.

              Additional keyword arguments are passed to the tool's generate() method.

              env.Tool('gcc')
              env.Tool('opengl', toolpath = ['build/tools'])

       Value(value, [built_value])

       env.Value(value, [built_value])
              Returns  a Node object representing the specified Python value.  Value Nodes can be
              used as dependencies of targets.  If  the  result  of  calling  str(value)  changes
              between  SCons  runs, any targets depending on Value(value) will be rebuilt.  (This
              is true even when using timestamps to decide if files are up-to-date.)  When  using
              timestamp  source  signatures, Value Nodes' timestamps are equal to the system time
              when the Node is created.

              The returned Value Node object has a write() method that can be used to  "build"  a
              Value  Node  by  setting  a  new  value.   The optional built_value argument can be
              specified when the Value Node is created to indicate the  Node  should  already  be
              considered  "built."   There  is a corresponding read() method that will return the
              built value of the Node.

              Examples:

              env = Environment()

              def create(target, source, env):
                  # A function that will write a 'prefix=$SOURCE'
                  # string into the file name specified as the
                  # $TARGET.
                  f = open(str(target[0]), 'wb')
                  f.write('prefix=' + source[0].get_contents())

              # Fetch the prefix= argument, if any, from the command
              # line, and use /usr/local as the default.
              prefix = ARGUMENTS.get('prefix', '/usr/local')

              # Attach a .Config() builder for the above function action
              # to the construction environment.
              env['BUILDERS']['Config'] = Builder(action = create)
              env.Config(target = 'package-config', source = Value(prefix))

              def build_value(target, source, env):
                  # A function that "builds" a Python Value by updating
                  # the the Python value with the contents of the file
                  # specified as the source of the Builder call ($SOURCE).
                  target[0].write(source[0].get_contents())

              output = env.Value('before')
              input = env.Value('after')

              # Attach a .UpdateValue() builder for the above function
              # action to the construction environment.
              env['BUILDERS']['UpdateValue'] = Builder(action = build_value)
              env.UpdateValue(target = Value(output), source = Value(input))

       VariantDir(variant_dir, src_dir, [duplicate])

       env.VariantDir(variant_dir, src_dir, [duplicate])
              Use the VariantDir() function to create a copy of your sources in another location:
              if  a  name  under  variant_dir  is not found but exists under src_dir, the file or
              directory is copied to variant_dir.  Target files  can  be  built  in  a  different
              directory than the original sources by simply refering to the sources (and targets)
              within the variant tree.

              VariantDir() can be called multiple times with the same src_dir to set up  multiple
              builds  with  different  options  (variants).   The  src_dir location must be in or
              underneath the SConstruct file's directory, and variant_dir may not  be  underneath
              src_dir.

              The  default  behavior is for scons to physically duplicate the source files in the
              variant tree.  Thus, a build performed in the variant  tree  is  guaranteed  to  be
              identical to a build performed in the source tree even if intermediate source files
              are generated during the build, or  preprocessors  or  other  scanners  search  for
              included  files  relative  to  the  source  file,  or individual compilers or other
              invoked tools are hard-coded to put derived files in the same directory  as  source
              files.

              If  possible  on  the platform, the duplication is performed by linking rather than
              copying; see also the --duplicate command-line option.  Moreover,  only  the  files
              needed  for  the  build are duplicated; files and directories that are not used are
              not present in variant_dir.

              Duplicating the source tree may be disabled by setting the duplicate argument to  0
              (zero).   This  will  cause scons to invoke Builders using the path names of source
              files in src_dir and the path names of derived files within variant_dir.   This  is
              always  more  efficient  than duplicate=1, and is usually safe for most builds (but
              see above for cases that may cause problems).

              Note that VariantDir() works most naturally  with  a  subsidiary  SConscript  file.
              However,  you  would  then  call  the  subsidiary SConscript file not in the source
              directory, but in the variant_dir, regardless of the value of duplicate.   This  is
              how you tell scons which variant of a source tree to build:

              # run src/SConscript in two variant directories
              VariantDir('build/variant1', 'src')
              SConscript('build/variant1/SConscript')
              VariantDir('build/variant2', 'src')
              SConscript('build/variant2/SConscript')

              See  also  the SConscript() function, described above, for another way to specify a
              variant directory in conjunction with calling a subsidiary SConscript file.

              Examples:

              # use names in the build directory, not the source directory
              VariantDir('build', 'src', duplicate=0)
              Program('build/prog', 'build/source.c')

              # this builds both the source and docs in a separate subtree
              VariantDir('build', '.', duplicate=0)
              SConscript(dirs=['build/src','build/doc'])

              # same as previous example, but only uses SConscript
              SConscript(dirs='src', variant_dir='build/src', duplicate=0)
              SConscript(dirs='doc', variant_dir='build/doc', duplicate=0)

       WhereIs(program, [path, pathext, reject])

       env.WhereIs(program, [path, pathext, reject])
              Searches for the specified executable program, returning the full path name to  the
              program  if  it  is found, and returning None if not.  Searches the specified path,
              the value of the calling environment's PATH  (env['ENV']['PATH']),  or  the  user's
              current  external  PATH  (os.environ['PATH'])  by  default.   On  Windows  systems,
              searches for executable programs with any of the  file  extensions  listed  in  the
              specified pathext, the calling environment's PATHEXT (env['ENV']['PATHEXT']) or the
              user's current PATHEXT (os.environ['PATHEXT']) by default.   Will  not  select  any
              path name or names in the specified reject list, if any.

   SConscript Variables
       In  addition  to  the  global  functions  and  methods,  scons supports a number of Python
       variables that can be used in SConscript files to affect how you  want  the  build  to  be
       performed.   These  variables  may  be accessed from custom Python modules that you import
       into an SConscript file by adding the following to the Python module:

              from SCons.Script import *

       ARGLIST
              A list keyword=value arguments specified on the command line.  Each element in  the
              list  is  a  tuple  containing  the  (keyword,value) of the argument.  The separate
              keyword and value elements of the tuple can be accessed by subscripting for element
              [0] and [1] of the tuple, respectively.

              Example:

              print "first keyword, value =", ARGLIST[0][0], ARGLIST[0][1]
              print "second keyword, value =", ARGLIST[1][0], ARGLIST[1][1]
              third_tuple = ARGLIST[2]
              print "third keyword, value =", third_tuple[0], third_tuple[1]
              for key, value in ARGLIST:
                  # process key and value

       ARGUMENTS
              A dictionary of all the keyword=value arguments specified on the command line.  The
              dictionary is not in order, and if a given keyword has more than one value assigned
              to  it on the command line, the last (right-most) value is the one in the ARGUMENTS
              dictionary.

              Example:

              if ARGUMENTS.get('debug', 0):
                  env = Environment(CCFLAGS = '-g')
              else:
                  env = Environment()

       BUILD_TARGETS
              A list of the targets which scons will actually try to build, regardless of whether
              they  were  specified  on the command line or via the Default() function or method.
              The elements of this list may be strings or nodes,  so  you  should  run  the  list
              through  the  Python str function to make sure any Node path names are converted to
              strings.

              Because this list may be taken  from  the  list  of  targets  specified  using  the
              Default()  function  or  method,  the  contents  of  the  list  may  change on each
              successive call to Default().  See the DEFAULT_TARGETS list, below, for  additional
              information.

              Example:

              if 'foo' in BUILD_TARGETS:
                  print "Don't forget to test the `foo' program!"
              if 'special/program' in BUILD_TARGETS:
                  SConscript('special')

              Note  that  the  BUILD_TARGETS  list  only  contains targets expected listed on the
              command line or via calls to the Default() function or method.  It does not contain
              all  dependent  targets  that  will  be  built  as  a result of making the sure the
              explicitly-specified targets are up to date.

       COMMAND_LINE_TARGETS
              A list of the targets explicitly specified on the command line.  If  there  are  no
              targets  specified  on  the command line, the list is empty.  This can be used, for
              example, to take specific  actions  only  when  a  certain  target  or  targets  is
              explicitly being built.

              Example:

              if 'foo' in COMMAND_LINE_TARGETS:
                  print "Don't forget to test the `foo' program!"
              if 'special/program' in COMMAND_LINE_TARGETS:
                  SConscript('special')

       DEFAULT_TARGETS
              A list of the target nodes that have been specified using the Default() function or
              method.  The elements of the list are nodes, so you need to run  them  through  the
              Python str function to get at the path name for each Node.

              Example:

              print str(DEFAULT_TARGETS[0])
              if 'foo' in map(str, DEFAULT_TARGETS):
                  print "Don't forget to test the `foo' program!"

              The  contents  of the DEFAULT_TARGETS list change on on each successive call to the
              Default() function:

              print map(str, DEFAULT_TARGETS)   # originally []
              Default('foo')
              print map(str, DEFAULT_TARGETS)   # now a node ['foo']
              Default('bar')
              print map(str, DEFAULT_TARGETS)   # now a node ['foo', 'bar']
              Default(None)
              print map(str, DEFAULT_TARGETS)   # back to []

              Consequently, be sure to use DEFAULT_TARGETS only after you've  made  all  of  your
              Default() calls, or else simply be careful of the order of these statements in your
              SConscript files so that you don't look for a specific default target  before  it's
              actually been added to the list.

   Construction Variables
       A construction environment has an associated dictionary of construction variables that are
       used by built-in or user-supplied build rules.  Construction  variables  must  follow  the
       same  rules for Python identifiers: the initial character must be an underscore or letter,
       followed by any number of underscores, letters, or digits.

       A number of useful construction variables are automatically  defined  by  scons  for  each
       supported  platform, and additional construction variables can be defined by the user. The
       following is a list of the automatically defined construction variables:

       AR     The static library archiver.

       ARCHITECTURE
              Specifies the system architecture for  which  the  package  is  being  built.   The
              default  is the system architecture of the machine on which SCons is running.  This
              is used to fill in the Architecture: field in an Ipkg control file, and as part  of
              the name of a generated RPM file.

       ARCOM  The command line used to generate a static library from object files.

       ARCOMSTR
              The  string  displayed  when  an object file is generated from an assembly-language
              source file.  If this is not set, then $ARCOM (the command line) is displayed.

              env = Environment(ARCOMSTR = "Archiving $TARGET")

       ARFLAGS
              General options passed to the static library archiver.

       AS     The assembler.

       ASCOM  The command line used to generate an object file from an  assembly-language  source
              file.

       ASCOMSTR
              The  string  displayed  when  an object file is generated from an assembly-language
              source file.  If this is not set, then $ASCOM (the command line) is displayed.

              env = Environment(ASCOMSTR = "Assembling $TARGET")

       ASFLAGS
              General options passed to the assembler.

       ASPPCOM
              The command line used to assemble an assembly-language source file into  an  object
              file  after  first  running  the  file  through  the  C  preprocessor.  Any options
              specified in the $ASFLAGS and $CPPFLAGS construction variables are included on this
              command line.

       ASPPCOMSTR
              The  string  displayed  when  an object file is generated from an assembly-language
              source file after first running the file through the C preprocessor.   If  this  is
              not set, then $ASPPCOM (the command line) is displayed.

              env = Environment(ASPPCOMSTR = "Assembling $TARGET")

       ASPPFLAGS
              General  options when an assembling an assembly-language source file into an object
              file after first running the file through the C preprocessor.  The  default  is  to
              use the value of $ASFLAGS.

       BIBTEX The  bibliography  generator  for  the  TeX  formatter and typesetter and the LaTeX
              structured formatter and typesetter.

       BIBTEXCOM
              The command line used to call the bibliography generator for the TeX formatter  and
              typesetter and the LaTeX structured formatter and typesetter.

       BIBTEXCOMSTR
              The  string  displayed when generating a bibliography for TeX or LaTeX.  If this is
              not set, then $BIBTEXCOM (the command line) is displayed.

              env = Environment(BIBTEXCOMSTR = "Generating bibliography $TARGET")

       BIBTEXFLAGS
              General options passed to the bibliography generator  for  the  TeX  formatter  and
              typesetter and the LaTeX structured formatter and typesetter.

       BITKEEPER
              The BitKeeper executable.

       BITKEEPERCOM
              The command line for fetching source files using BitKeeper.

       BITKEEPERCOMSTR
              The  string  displayed when fetching a source file using BitKeeper.  If this is not
              set, then $BITKEEPERCOM (the command line) is displayed.

       BITKEEPERGET
              The command ($BITKEEPER) and subcommand for fetching source files using BitKeeper.

       BITKEEPERGETFLAGS
              Options that are passed to the BitKeeper get subcommand.

       BUILDERS
              A dictionary mapping the names of the builders available through  this  environment
              to underlying Builder objects.  Builders named Alias, CFile, CXXFile, DVI, Library,
              Object, PDF, PostScript, and Program are available by default.  If  you  initialize
              this variable when an Environment is created:

              env = Environment(BUILDERS = {'NewBuilder' : foo})

              the  default  Builders will no longer be available.  To use a new Builder object in
              addition to the default Builders, add your new Builder object like this:

              env = Environment()
              env.Append(BUILDERS = {'NewBuilder' : foo})

              or this:

              env = Environment()
              env['BUILDERS]['NewBuilder'] = foo

       CC     The C compiler.

       CCCOM  The command line used to compile a C source file to a (static)  object  file.   Any
              options specified in the $CFLAGS, $CCFLAGS and $CPPFLAGS construction variables are
              included on this command line.

       CCCOMSTR
              The string displayed when a C source file is compiled to a  (static)  object  file.
              If this is not set, then $CCCOM (the command line) is displayed.

              env = Environment(CCCOMSTR = "Compiling static object $TARGET")

       CCFLAGS
              General options that are passed to the C and C++ compilers.

       CCPCHFLAGS
              Options  added  to  the  compiler command line to support building with precompiled
              headers.  The default value expands expands to the appropriate Microsoft Visual C++
              command-line options when the $PCH construction variable is set.

       CCPDBFLAGS
              Options added to the compiler command line to support storing debugging information
              in a Microsoft  Visual  C++  PDB  file.   The  default  value  expands  expands  to
              appropriate  Microsoft  Visual  C++ command-line options when the $PDB construction
              variable is set.

              The Visual C++  compiler  option  that  SCons  uses  by  default  to  generate  PDB
              information  is  /Z7.   This  works  correctly with parallel (-j) builds because it
              embeds the debug information in  the  intermediate  object  files,  as  opposed  to
              sharing a single PDB file between multiple object files.  This is also the only way
              to get debug information embedded into a static library.  Using the /Zi instead may
              yield improved link-time performance, although parallel builds will no longer work.

              You  can  generate  PDB  files  with  the  /Zi  switch  by  overriding  the default
              $CCPDBFLAGS variable as follows:

              env['CCPDBFLAGS'] = ['${(PDB and "/Zi /Fd%s" % File(PDB)) or ""}']

              An alternative would be to use the /Zi  to  put  the  debugging  information  in  a
              separate  .pdb  file for each object file by overriding the $CCPDBFLAGS variable as
              follows:

              env['CCPDBFLAGS'] = '/Zi /Fd${TARGET}.pdb'

       CCVERSION
              The version number of the C compiler.  This may or may not be set, depending on the
              specific C compiler being used.

       CFILESUFFIX
              The  suffix  for  C  source files.  This is used by the internal CFile builder when
              generating C files from Lex (.l) or YACC (.y) input files.  The default suffix,  of
              course, is .c (lower case).  On case-insensitive systems (like Windows), SCons also
              treats .C (upper case) files as C files.

       CFLAGS General options that are passed to the C compiler (C only; not C++).

       CHANGE_SPECFILE
              A hook for modifying the file that controls the packaging build (the .spec for RPM,
              the control for Ipkg, the .wxs for MSI).  If set, the function will be called after
              the SCons template for the file has been written.  XXX

       CHANGED_SOURCES
              A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       CHANGED_TARGETS
              A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       CHANGELOG
              The name of a file containing the change log text to be included  in  the  package.
              This is included as the %changelog section of the RPM .spec file.

       _concat
              A  function  used  to  produce  variables like $_CPPINCFLAGS. It takes four or five
              arguments: a prefix to concatenate onto each element, a list of elements, a  suffix
              to concatenate onto each element, an environment for variable interpolation, and an
              optional function that will be called to transform the list before concatenation.

              env['_CPPINCFLAGS'] = '$( ${_concat(INCPREFIX, CPPPATH, INCSUFFIX, __env__, RDirs)} $)',

       CONFIGUREDIR
              The name of the directory in which Configure context test files are  written.   The
              default is .sconf_temp in the top-level directory containing the SConstruct file.

       CONFIGURELOG
              The  name of the Configure context log file.  The default is config.log in the top-
              level directory containing the SConstruct file.

       _CPPDEFFLAGS
              An automatically-generated construction  variable  containing  the  C  preprocessor
              command-line  options  to  define values.  The value of $_CPPDEFFLAGS is created by
              appending $CPPDEFPREFIX  and  $CPPDEFSUFFIX  to  the  beginning  and  end  of  each
              definition in $CPPDEFINES.

       CPPDEFINES
              A   platform   independent   specification  of  C  preprocessor  definitions.   The
              definitions will be added to  command  lines  through  the  automatically-generated
              $_CPPDEFFLAGS  construction variable (see above), which is constructed according to
              the type of value of $CPPDEFINES:

              If $CPPDEFINES  is  a  string,  the  values  of  the  $CPPDEFPREFIXand$CPPDEFSUFFIX
              construction variables will be added to the beginning and end.

              # Will add -Dxyz to POSIX compiler command lines,
              # and /Dxyz to Microsoft Visual C++ command lines.
              env = Environment(CPPDEFINES='xyz')

              If   $CPPDEFINES  is  a  list,  the  values  of  the  $CPPDEFPREFIXand$CPPDEFSUFFIX
              construction variables will be appended to the beginning and end of each element in
              the list.  If any element is a list or tuple, then the first item is the name being
              defined and the second item is its value:

              # Will add -DB=2 -DA to POSIX compiler command lines,
              # and /DB=2 /DA to Microsoft Visual C++ command lines.
              env = Environment(CPPDEFINES=[('B', 2), 'A'])

              If $CPPDEFINES is a dictionary, the  values  of  the  $CPPDEFPREFIXand$CPPDEFSUFFIX
              construction  variables will be appended to the beginning and end of each item from
              the dictionary.  The key of each dictionary item is a name  being  defined  to  the
              dictionary  item's  corresponding  value;  if  the  value is None, then the name is
              defined without an explicit value.  Note that the resulting  flags  are  sorted  by
              keyword  to  ensure that the order of the options on the command line is consistent
              each time scons is run.

              # Will add -DA -DB=2 to POSIX compiler command lines,
              # and /DA /DB=2 to Microsoft Visual C++ command lines.
              env = Environment(CPPDEFINES={'B':2, 'A':None})

       CPPDEFPREFIX
              The prefix used to specify preprocessor definitions on the C compiler command line.
              This  will  be  appended  to  the  beginning  of each definition in the $CPPDEFINES
              construction variable when the $_CPPDEFFLAGS variable is automatically generated.

       CPPDEFSUFFIX
              The suffix used to specify preprocessor definitions on the C compiler command line.
              This will be appended to the end of each definition in the $CPPDEFINES construction
              variable when the $_CPPDEFFLAGS variable is automatically generated.

       CPPFLAGS
              User-specified C preprocessor options.  These will be included in any command  that
              uses  the  C preprocessor, including not just compilation of C and C++ source files
              via the $CCCOM, $SHCCCOM,  $CXXCOM  and  $SHCXXCOM  command  lines,  but  also  the
              $FORTRANPPCOM,  $SHFORTRANPPCOM,  $F77PPCOM  and  $SHF77PPCOM command lines used to
              compile a Fortran source file, and the $ASPPCOM command line used  to  assemble  an
              assembly  language  source  file,  after  first  running  each  file  through the C
              preprocessor.  Note that this variable does not contain  -I  (or  similar)  include
              search  path  options  that  scons  generates  automatically  from  $CPPPATH.   See
              $_CPPINCFLAGS, below, for the variable that expands to those options.

       _CPPINCFLAGS
              An automatically-generated construction  variable  containing  the  C  preprocessor
              command-line  options  for specifying directories to be searched for include files.
              The value of $_CPPINCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the
              beginning and end of each directory in $CPPPATH.

       CPPPATH
              The   list  of  directories  that  the  C  preprocessor  will  search  for  include
              directories. The C/C++ implicit dependency scanner will  search  these  directories
              for  include  files. Don't explicitly put include directory arguments in CCFLAGS or
              CXXFLAGS because the result will be non-portable and the directories  will  not  be
              searched  by  the  dependency  scanner.  Note:  directory  names in CPPPATH will be
              looked-up relative to the SConscript directory when they are used in a command.  To
              force scons to look-up a directory relative to the root of the source tree use #:

              env = Environment(CPPPATH='#/include')

              The directory look-up can also be forced using the Dir() function:

              include = Dir('include')
              env = Environment(CPPPATH=include)

              The  directory  list  will  be  added  to  command lines through the automatically-
              generated $_CPPINCFLAGS construction variable, which is  constructed  by  appending
              the  values  of the $INCPREFIXand$INCSUFFIX construction variables to the beginning
              and end of each directory in $CPPPATH.  Any command lines you define that need  the
              CPPPATH directory list should include $_CPPINCFLAGS:

              env = Environment(CCCOM="my_compiler $_CPPINCFLAGS -c -o $TARGET $SOURCE")

       CPPSUFFIXES
              The  list  of  suffixes  of  files that will be scanned for C preprocessor implicit
              dependencies (#include lines).  The default list is:

              [".c", ".C", ".cxx", ".cpp", ".c++", ".cc",
               ".h", ".H", ".hxx", ".hpp", ".hh",
               ".F", ".fpp", ".FPP",
               ".m", ".mm",
               ".S", ".spp", ".SPP"]

       CVS    The CVS executable.

       CVSCOFLAGS
              Options that are passed to the CVS checkout subcommand.

       CVSCOM The command line used to fetch source files from a CVS repository.

       CVSCOMSTR
              The string displayed when fetching a source file from a CVS repository.  If this is
              not set, then $CVSCOM (the command line) is displayed.

       CVSFLAGS
              General  options  that  are  passed  to  CVS.   By  default,  this  is  set  to  -d
              $CVSREPOSITORY to specify from where the files must be fetched.

       CVSREPOSITORY
              The path to the CVS repository.  This is referenced in the default $CVSFLAGS value.

       CXX    The C++ compiler.

       CXXCOM The command line used to compile a C++ source file to an object file.  Any  options
              specified  in  the  $CXXFLAGS  and $CPPFLAGS construction variables are included on
              this command line.

       CXXCOMSTR
              The string displayed when a C++ source file is compiled to a (static) object  file.
              If this is not set, then $CXXCOM (the command line) is displayed.

              env = Environment(CXXCOMSTR = "Compiling static object $TARGET")

       CXXFILESUFFIX
              The suffix for C++ source files.  This is used by the internal CXXFile builder when
              generating C++ files from Lex (.ll) or YACC (.yy) input files.  The default  suffix
              is  .cc.   SCons  also treats files with the suffixes .cpp, .cxx, .c++, and .C++ as
              C++ files, and files with .mm suffixes as Objective C++ files.   On  case-sensitive
              systems  (Linux,  UNIX,  and other POSIX-alikes), SCons also treats .C (upper case)
              files as C++ files.

       CXXFLAGS
              General options that are passed to the C++ compiler.  By default, this includes the
              value of $CCFLAGS, so that setting $CCFLAGS affects both C and C++ compilation.  If
              you want to add  C++-specific  flags,  you  must  set  or  override  the  value  of
              $CXXFLAGS.

       CXXVERSION
              The  version  number of the C++ compiler.  This may or may not be set, depending on
              the specific C++ compiler being used.

       DESCRIPTION
              A long description of the project being packaged.  This is included in the relevant
              section of the file that controls the packaging build.

       DESCRIPTION_lang
              A  language-specific  long  description  for  the  specified lang.  This is used to
              populate a %description -l section of an RPM .spec file.

       Dir    A function that converts a string into a Dir instance relative to the target  being
              built.

       Dirs   A function that converts a list of strings into a list of Dir instances relative to
              the target being built.

       DSUFFIXES
              The list of suffixes of files that will be scanned for imported  D  package  files.
              The default list is:

              ['.d']

       DVIPDF The TeX DVI file to PDF file converter.

       DVIPDFCOM
              The command line used to convert TeX DVI files into a PDF file.

       DVIPDFCOMSTR
              The  string displayed when a TeX DVI file is converted into a PDF file.  If this is
              not set, then $DVIPDFCOM (the command line) is displayed.

       DVIPDFFLAGS
              General options passed to the TeX DVI file to PDF file converter.

       DVIPS  The TeX DVI file to PostScript converter.

       DVIPSFLAGS
              General options passed to the TeX DVI file to PostScript converter.

       ENV    A dictionary of environment variables to use when invoking commands. When  $ENV  is
              used  in  a command all list values will be joined using the path separator and any
              other non-string values will simply be coerced to a string.  Note that, by default,
              scons  does  not  propagate  the environment in force when you execute scons to the
              commands used to build target files.  This is so that  builds  will  be  guaranteed
              repeatable  regardless  of  the  environment  variables  set  at  the time scons is
              invoked.

              If you want to propagate your environment variables to  the  commands  executed  to
              build target files, you must do so explicitly:

              import os
              env = Environment(ENV = os.environ)

              Note that you can choose only to propagate certain environment variables.  A common
              example is the system PATH environment  variable,  so  that  scons  uses  the  same
              utilities as the invoking shell (or other process):

              import os
              env = Environment(ENV = {'PATH' : os.environ['PATH']})

       ESCAPE A function that will be called to escape shell special characters in command lines.
              The function should take one argument: the  command  line  string  to  escape;  and
              should return the escaped command line.

       F77    The  Fortran  77  compiler.   You  should normally set the $FORTRAN variable, which
              specifies the default Fortran compiler for all Fortran versions.  You only need  to
              set  $F77 if you need to use a specific compiler or compiler version for Fortran 77
              files.

       F77COM The command line used to compile a Fortran 77 source file to an object  file.   You
              only  need to set $F77COM if you need to use a specific command line for Fortran 77
              files.  You should normally set  the  $FORTRANCOM  variable,  which  specifies  the
              default command line for all Fortran versions.

       F77COMSTR
              The  string  displayed when a Fortran 77 source file is compiled to an object file.
              If this is not set, then $F77COM or $FORTRANCOM (the command line) is displayed.

       F77FILESUFFIXES
              The list of file extensions for which the F77 dialect will  be  used.  By  default,
              this is ['.f77']

       F77FLAGS
              General  user-specified  options  that are passed to the Fortran 77 compiler.  Note
              that this variable does not contain -I (or similar)  include  search  path  options
              that scons generates automatically from $F77PATH.  See $_F77INCFLAGS below, for the
              variable that expands to those options.  You only need to set $F77FLAGS if you need
              to  define specific user options for Fortran 77 files.  You should normally set the
              $FORTRANFLAGS variable, which specifies the user-specified options  passed  to  the
              default Fortran compiler for all Fortran versions.

       _F77INCFLAGS
              An automatically-generated construction variable containing the Fortran 77 compiler
              command-line options for specifying directories to be searched for  include  files.
              The value of $_F77INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the
              beginning and end of each directory in $F77PATH.

       F77PATH
              The list of directories that the  Fortran  77  compiler  will  search  for  include
              directories.  The  implicit  dependency  scanner  will search these directories for
              include files. Don't  explicitly  put  include  directory  arguments  in  $F77FLAGS
              because the result will be non-portable and the directories will not be searched by
              the dependency scanner.  Note:  directory  names  in  $F77PATH  will  be  looked-up
              relative  to  the  SConscript  directory  when they are used in a command. To force
              scons to look-up a directory relative to the root of the source  tree  use  #:  You
              only need to set $F77PATH if you need to define a specific include path for Fortran
              77 files.  You should normally set the $FORTRANPATH variable, which  specifies  the
              include path for the default Fortran compiler for all Fortran versions.

              env = Environment(F77PATH='#/include')

              The directory look-up can also be forced using the Dir() function:

              include = Dir('include')
              env = Environment(F77PATH=include)

              The  directory  list  will  be  added  to  command lines through the automatically-
              generated $_F77INCFLAGS construction variable, which is  constructed  by  appending
              the  values  of the $INCPREFIXand$INCSUFFIX construction variables to the beginning
              and end of each directory in $F77PATH.  Any command lines you define that need  the
              F77PATH directory list should include $_F77INCFLAGS:

              env = Environment(F77COM="my_compiler $_F77INCFLAGS -c -o $TARGET $SOURCE")

       F77PPCOM
              The  command  line used to compile a Fortran 77 source file to an object file after
              first running the file through the C preprocessor.  Any options  specified  in  the
              $F77FLAGS  and  $CPPFLAGS construction variables are included on this command line.
              You only need to set $F77PPCOM if you need to use a specific C-preprocessor command
              line  for  Fortran  77  files.  You should normally set the $FORTRANPPCOM variable,
              which specifies the default C-preprocessor command line for all Fortran versions.

       F77PPCOMSTR
              The string displayed when a Fortran 77 source file is compiled to  an  object  file
              after  first running the file through the C preprocessor.  If this is not set, then
              $F77PPCOM or $FORTRANPPCOM (the command line) is displayed.

       F77PPFILESUFFIXES
              The list of file extensions for which the compilation + preprocessor pass  for  F77
              dialect will be used. By default, this is empty

       F90    The  Fortran  90  compiler.   You  should normally set the $FORTRAN variable, which
              specifies the default Fortran compiler for all Fortran versions.  You only need  to
              set  $F90 if you need to use a specific compiler or compiler version for Fortran 90
              files.

       F90COM The command line used to compile a Fortran 90 source file to an object  file.   You
              only  need to set $F90COM if you need to use a specific command line for Fortran 90
              files.  You should normally set  the  $FORTRANCOM  variable,  which  specifies  the
              default command line for all Fortran versions.

       F90COMSTR
              The  string  displayed when a Fortran 90 source file is compiled to an object file.
              If this is not set, then $F90COM or $FORTRANCOM (the command line) is displayed.

       F90FILESUFFIXES
              The list of file extensions for which the F90 dialect will  be  used.  By  default,
              this is ['.f90']

       F90FLAGS
              General  user-specified  options  that are passed to the Fortran 90 compiler.  Note
              that this variable does not contain -I (or similar)  include  search  path  options
              that scons generates automatically from $F90PATH.  See $_F90INCFLAGS below, for the
              variable that expands to those options.  You only need to set $F90FLAGS if you need
              to  define specific user options for Fortran 90 files.  You should normally set the
              $FORTRANFLAGS variable, which specifies the user-specified options  passed  to  the
              default Fortran compiler for all Fortran versions.

       _F90INCFLAGS
              An automatically-generated construction variable containing the Fortran 90 compiler
              command-line options for specifying directories to be searched for  include  files.
              The value of $_F90INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the
              beginning and end of each directory in $F90PATH.

       F90PATH
              The list of directories that the  Fortran  90  compiler  will  search  for  include
              directories.  The  implicit  dependency  scanner  will search these directories for
              include files. Don't  explicitly  put  include  directory  arguments  in  $F90FLAGS
              because the result will be non-portable and the directories will not be searched by
              the dependency scanner.  Note:  directory  names  in  $F90PATH  will  be  looked-up
              relative  to  the  SConscript  directory  when they are used in a command. To force
              scons to look-up a directory relative to the root of the source  tree  use  #:  You
              only need to set $F90PATH if you need to define a specific include path for Fortran
              90 files.  You should normally set the $FORTRANPATH variable, which  specifies  the
              include path for the default Fortran compiler for all Fortran versions.

              env = Environment(F90PATH='#/include')

              The directory look-up can also be forced using the Dir() function:

              include = Dir('include')
              env = Environment(F90PATH=include)

              The  directory  list  will  be  added  to  command lines through the automatically-
              generated $_F90INCFLAGS construction variable, which is  constructed  by  appending
              the  values  of the $INCPREFIXand$INCSUFFIX construction variables to the beginning
              and end of each directory in $F90PATH.  Any command lines you define that need  the
              F90PATH directory list should include $_F90INCFLAGS:

              env = Environment(F90COM="my_compiler $_F90INCFLAGS -c -o $TARGET $SOURCE")

       F90PPCOM
              The  command  line used to compile a Fortran 90 source file to an object file after
              first running the file through the C preprocessor.  Any options  specified  in  the
              $F90FLAGS  and  $CPPFLAGS construction variables are included on this command line.
              You only need to set $F90PPCOM if you need to use a specific C-preprocessor command
              line  for  Fortran  90  files.  You should normally set the $FORTRANPPCOM variable,
              which specifies the default C-preprocessor command line for all Fortran versions.

       F90PPCOMSTR
              The string displayed when a Fortran 90 source file is compiled after first  running
              the  file  through  the  C  preprocessor.   If  this  is not set, then $F90PPCOM or
              $FORTRANPPCOM (the command line) is displayed.

       F90PPFILESUFFIXES
              The list of file extensions for which the compilation + preprocessor pass  for  F90
              dialect will be used. By default, this is empty

       F95    The  Fortran  95  compiler.   You  should normally set the $FORTRAN variable, which
              specifies the default Fortran compiler for all Fortran versions.  You only need  to
              set  $F95 if you need to use a specific compiler or compiler version for Fortran 95
              files.

       F95COM The command line used to compile a Fortran 95 source file to an object  file.   You
              only  need to set $F95COM if you need to use a specific command line for Fortran 95
              files.  You should normally set  the  $FORTRANCOM  variable,  which  specifies  the
              default command line for all Fortran versions.

       F95COMSTR
              The  string  displayed when a Fortran 95 source file is compiled to an object file.
              If this is not set, then $F95COM or $FORTRANCOM (the command line) is displayed.

       F95FILESUFFIXES
              The list of file extensions for which the F95 dialect will  be  used.  By  default,
              this is ['.f95']

       F95FLAGS
              General  user-specified  options  that are passed to the Fortran 95 compiler.  Note
              that this variable does not contain -I (or similar)  include  search  path  options
              that scons generates automatically from $F95PATH.  See $_F95INCFLAGS below, for the
              variable that expands to those options.  You only need to set $F95FLAGS if you need
              to  define specific user options for Fortran 95 files.  You should normally set the
              $FORTRANFLAGS variable, which specifies the user-specified options  passed  to  the
              default Fortran compiler for all Fortran versions.

       _F95INCFLAGS
              An automatically-generated construction variable containing the Fortran 95 compiler
              command-line options for specifying directories to be searched for  include  files.
              The value of $_F95INCFLAGS is created by appending $INCPREFIX and $INCSUFFIX to the
              beginning and end of each directory in $F95PATH.

       F95PATH
              The list of directories that the  Fortran  95  compiler  will  search  for  include
              directories.  The  implicit  dependency  scanner  will search these directories for
              include files. Don't  explicitly  put  include  directory  arguments  in  $F95FLAGS
              because the result will be non-portable and the directories will not be searched by
              the dependency scanner.  Note:  directory  names  in  $F95PATH  will  be  looked-up
              relative  to  the  SConscript  directory  when they are used in a command. To force
              scons to look-up a directory relative to the root of the source  tree  use  #:  You
              only need to set $F95PATH if you need to define a specific include path for Fortran
              95 files.  You should normally set the $FORTRANPATH variable, which  specifies  the
              include path for the default Fortran compiler for all Fortran versions.

              env = Environment(F95PATH='#/include')

              The directory look-up can also be forced using the Dir() function:

              include = Dir('include')
              env = Environment(F95PATH=include)

              The  directory  list  will  be  added  to  command lines through the automatically-
              generated $_F95INCFLAGS construction variable, which is  constructed  by  appending
              the  values  of the $INCPREFIXand$INCSUFFIX construction variables to the beginning
              and end of each directory in $F95PATH.  Any command lines you define that need  the
              F95PATH directory list should include $_F95INCFLAGS:

              env = Environment(F95COM="my_compiler $_F95INCFLAGS -c -o $TARGET $SOURCE")

       F95PPCOM
              The  command  line used to compile a Fortran 95 source file to an object file after
              first running the file through the C preprocessor.  Any options  specified  in  the
              $F95FLAGS  and  $CPPFLAGS construction variables are included on this command line.
              You only need to set $F95PPCOM if you need to use a specific C-preprocessor command
              line  for  Fortran  95  files.  You should normally set the $FORTRANPPCOM variable,
              which specifies the default C-preprocessor command line for all Fortran versions.

       F95PPCOMSTR
              The string displayed when a Fortran 95 source file is compiled to  an  object  file
              after  first running the file through the C preprocessor.  If this is not set, then
              $F95PPCOM or $FORTRANPPCOM (the command line) is displayed.

       F95PPFILESUFFIXES
              The list of file extensions for which the compilation + preprocessor pass  for  F95
              dialect will be used. By default, this is empty

       File   A function that converts a string into a File instance relative to the target being
              built.

       FORTRAN
              The default Fortran compiler for all versions of Fortran.

       FORTRANCOM
              The command line used to compile a Fortran source  file  to  an  object  file.   By
              default,  any  options  specified  in  the $FORTRANFLAGS, $CPPFLAGS, $_CPPDEFFLAGS,
              $_FORTRANMODFLAG, and $_FORTRANINCFLAGS construction variables are included on this
              command line.

       FORTRANCOMSTR
              The  string displayed when a Fortran source file is compiled to an object file.  If
              this is not set, then $FORTRANCOM (the command line) is displayed.

       FORTRANFILESUFFIXES
              The list of file extensions for which the FORTRAN dialect will be used. By default,
              this is ['.f', '.for', '.ftn']

       FORTRANFLAGS
              General  user-specified options that are passed to the Fortran compiler.  Note that
              this variable does not contain -I  (or  similar)  include  or  module  search  path
              options    that    scons    generates   automatically   from   $FORTRANPATH.    See
              $_FORTRANINCFLAGSand$_FORTRANMODFLAG, below, for the variables  that  expand  those
              options.

       _FORTRANINCFLAGS
              An  automatically-generated  construction  variable containing the Fortran compiler
              command-line options for specifying directories to be searched  for  include  files
              and    module    files.    The   value   of   $_FORTRANINCFLAGS   is   created   by
              prepending/appending $INCPREFIX and $INCSUFFIX to the beginning  and  end  of  each
              directory in $FORTRANPATH.

       FORTRANMODDIR
              Directory  location  where  the  Fortran  compiler should place any module files it
              generates.  This variable  is  empty,  by  default.  Some  Fortran  compilers  will
              internally append this directory in the search path for module files, as well.

       FORTRANMODDIRPREFIX
              The prefix used to specify a module directory on the Fortran compiler command line.
              This will be appended to the beginning  of  the  directory  in  the  $FORTRANMODDIR
              construction   variables  when  the  $_FORTRANMODFLAG  variables  is  automatically
              generated.

       FORTRANMODDIRSUFFIX
              The suffix used to specify a module directory on the Fortran compiler command line.
              This  will  be  appended  to  the  beginning of the directory in the $FORTRANMODDIR
              construction  variables  when  the  $_FORTRANMODFLAG  variables  is   automatically
              generated.

       _FORTRANMODFLAG
              An  automatically-generated  construction  variable containing the Fortran compiler
              command-line option  for  specifying  the  directory  location  where  the  Fortran
              compiler  should  place  any  module  files  that  happen  to  get generated during
              compilation.  The value of  $_FORTRANMODFLAG  is  created  by  prepending/appending
              $FORTRANMODDIRPREFIX  and  $FORTRANMODDIRSUFFIX  to  the  beginning  and end of the
              directory in $FORTRANMODDIR.

       FORTRANMODPREFIX
              The module file prefix used by  the  Fortran  compiler.   SCons  assumes  that  the
              Fortran  compiler  follows the quasi-standard naming convention for module files of
              module_name.mod.  As a result, this  variable  is  left  empty,  by  default.   For
              situations in which the compiler does not necessarily follow the normal convention,
              the user may use this variable.  Its value will be appended to  every  module  file
              name as scons attempts to resolve dependencies.

       FORTRANMODSUFFIX
              The  module  file  suffix  used  by  the  Fortran compiler.  SCons assumes that the
              Fortran compiler follows the quasi-standard naming convention for module  files  of
              module_name.mod.   As  a  result,  this variable is set to ".mod", by default.  For
              situations in which the compiler does not necessarily follow the normal convention,
              the  user  may  use this variable.  Its value will be appended to every module file
              name as scons attempts to resolve dependencies.

       FORTRANPATH
              The list of directories that the Fortran compiler will search for include files and
              (for  some  compilers)  module  files. The Fortran implicit dependency scanner will
              search these directories for include files (but not module  files  since  they  are
              autogenerated  and,  as  such,  may  not  actually exist at the time the scan takes
              place). Don't explicitly put include directory arguments  in  FORTRANFLAGS  because
              the  result  will  be  non-portable and the directories will not be searched by the
              dependency scanner. Note: directory names in FORTRANPATH will be looked-up relative
              to  the  SConscript  directory  when  they are used in a command. To force scons to
              look-up a directory relative to the root of the source tree use #:

              env = Environment(FORTRANPATH='#/include')

              The directory look-up can also be forced using the Dir() function:

              include = Dir('include')
              env = Environment(FORTRANPATH=include)

              The directory list will be  added  to  command  lines  through  the  automatically-
              generated   $_FORTRANINCFLAGS   construction  variable,  which  is  constructed  by
              appending the values of the $INCPREFIXand$INCSUFFIX construction variables  to  the
              beginning  and end of each directory in $FORTRANPATH.  Any command lines you define
              that need the FORTRANPATH directory list should include $_FORTRANINCFLAGS:

              env = Environment(FORTRANCOM="my_compiler $_FORTRANINCFLAGS -c -o $TARGET $SOURCE")

       FORTRANPPCOM
              The command line used to compile a Fortran source file  to  an  object  file  after
              first  running  the  file  through  the  C  preprocessor.   By default, any options
              specified in the $FORTRANFLAGS,  $CPPFLAGS,  $_CPPDEFFLAGS,  $_FORTRANMODFLAG,  and
              $_FORTRANINCFLAGS construction variables are included on this command line.

       FORTRANPPCOMSTR
              The string displayed when a Fortran source file is compiled to an object file after
              first running the file through the C  preprocessor.   If  this  is  not  set,  then
              $FORTRANPPCOM (the command line) is displayed.

       FORTRANPPFILESUFFIXES
              The  list  of  file  extensions  for  which the compilation + preprocessor pass for
              FORTRAN dialect will be used. By default, this is ['.fpp', '.FPP']

       FORTRANSUFFIXES
              The  list  of  suffixes  of  files  that  will  be  scanned  for  Fortran  implicit
              dependencies (INCLUDE lines and USE statements).  The default list is:

              [".f", ".F", ".for", ".FOR", ".ftn", ".FTN", ".fpp", ".FPP",
              ".f77", ".F77", ".f90", ".F90", ".f95", ".F95"]

       FRAMEWORKPATH
              On  Mac  OS X with gcc, a list containing the paths to search for frameworks.  Used
              by the compiler to find framework-style  includes  like  #include  <Fmwk/Header.h>.
              Used   by   the   linker  to  find  user-specified  frameworks  when  linking  (see
              $FRAMEWORKS).  For example:

               env.AppendUnique(FRAMEWORKPATH='#myframeworkdir')

              will add

                ... -Fmyframeworkdir

              to the compiler and linker command lines.

       _FRAMEWORKPATH
              On Mac OS X with gcc, an automatically-generated construction  variable  containing
              the linker command-line options corresponding to $FRAMEWORKPATH.

       FRAMEWORKPATHPREFIX
              On  Mac  OS  X with gcc, the prefix to be used for the FRAMEWORKPATH entries.  (see
              $FRAMEWORKPATH).  The default value is -F.

       FRAMEWORKPREFIX
              On Mac OS X with gcc, the  prefix  to  be  used  for  linking  in  frameworks  (see
              $FRAMEWORKS).  The default value is -framework.

       _FRAMEWORKS
              On  Mac  OS X with gcc, an automatically-generated construction variable containing
              the linker command-line options for linking with FRAMEWORKS.

       FRAMEWORKS
              On Mac OS X with gcc, a list of the framework names to be linked into a program  or
              shared library or bundle.  The default value is the empty list.  For example:

               env.AppendUnique(FRAMEWORKS=Split('System Cocoa SystemConfiguration'))

       FRAMEWORKSFLAGS
              On  Mac  OS X with gcc, general user-supplied frameworks options to be added at the
              end of a  command  line  building  a  loadable  module.   (This  has  been  largely
              superseded   by  the  $FRAMEWORKPATH,  $FRAMEWORKPATHPREFIX,  $FRAMEWORKPREFIX  and
              $FRAMEWORKS variables described above.)

       GS     The Ghostscript program used to convert PostScript to PDF files.

       GSCOM  The Ghostscript command line used to convert PostScript to PDF files.

       GSCOMSTR
              The string displayed when Ghostscript is used to convert a PostScript file to a PDF
              file.  If this is not set, then $GSCOM (the command line) is displayed.

       GSFLAGS
              General options passed to the Ghostscript program when converting PostScript to PDF
              files.

       HOST_ARCH
              Sets the host architecture for Visual Studio compiler. If not set, default  to  the
              detected  host architecture: note that this may depend on the python you are using.
              This variable must be passed as  an  argument  to  the  Environment()  constructor;
              setting it later has no effect.

              Valid values are the same as for $TARGET_ARCH.

              This  is currently only used on Windows, but in the future it will be used on other
              OSes as well.

       HOST_OS
                      The name of the host operating system used to create the Environment.
                      If a platform is specified when creating the Environment, then
                      that Platform's logic will handle setting this value.
                      This value is immutable, and should not be changed by the user after
                      the Environment is initialized.
                      Currently only set for Win32.

       IDLSUFFIXES
              The list of suffixes of files that will be scanned for  IDL  implicit  dependencies
              (#include or import lines).  The default list is:

              [".idl", ".IDL"]

       IMPLICIT_COMMAND_DEPENDENCIES
              Controls  whether  or  not  SCons  will  add implicit dependencies for the commands
              executed to build targets.

              By default, SCons will add to each target an implicit  dependency  on  the  command
              represented  by  the  first argument on any command line it executes.  The specific
              file for the dependency is  found  by  searching  the  PATH  variable  in  the  ENV
              environment used to execute the command.

              If the construction variable $IMPLICIT_COMMAND_DEPENDENCIES is set to a false value
              (None, False, 0, etc.), then the implicit dependency  will  not  be  added  to  the
              targets built with that construction environment.

              env = Environment(IMPLICIT_COMMAND_DEPENDENCIES = 0)

       INCPREFIX
              The  prefix  used  to  specify an include directory on the C compiler command line.
              This will be appended to the beginning  of  each  directory  in  the  $CPPPATH  and
              $FORTRANPATH  construction  variables  when the $_CPPINCFLAGS and $_FORTRANINCFLAGS
              variables are automatically generated.

       INCSUFFIX
              The suffix used to specify an include directory on the  C  compiler  command  line.
              This will be appended to the end of each directory in the $CPPPATH and $FORTRANPATH
              construction variables when the $_CPPINCFLAGS and $_FORTRANINCFLAGS  variables  are
              automatically generated.

       INSTALL
              A  function  to  be  called  to  install  a file into a destination file name.  The
              default function copies the file into the destination  (and  sets  the  destination
              file's  mode  and  permission bits to match the source file's).  The function takes
              the following arguments:

              def install(dest, source, env):

              dest is the path name of the destination file.  source is  the  path  name  of  the
              source  file.   env  is  the construction environment (a dictionary of construction
              values) in force for this file installation.

       INSTALLSTR
              The string displayed when a file is installed into a destination  file  name.   The
              default is:
              Install file: "$SOURCE" as "$TARGET"

       INTEL_C_COMPILER_VERSION
              Set  by  the  "intelc"  Tool  to  the  major version number of the Intel C compiler
              selected for use.

       JAR    The Java archive tool.

       JARCHDIR
              The directory to which the Java archive tool should change (using the -C option).

       JARCOM The command line used to call the Java archive tool.

       JARCOMSTR
              The string displayed when the Java archive tool is called If this is not set,  then
              $JARCOM (the command line) is displayed.

              env = Environment(JARCOMSTR = "JARchiving $SOURCES into $TARGET")

       JARFLAGS
              General  options  passed to the Java archive tool.  By default this is set to cf to
              create the necessary jar file.

       JARSUFFIX
              The suffix for Java archives: .jar by default.

       JAVABOOTCLASSPATH
              Specifies the list of directories that will be added to the  &javac;  command  line
              via the -bootclasspath option.  The individual directory names will be separated by
              the operating system's  path  separate  character  (:  on  UNIX/Linux/POSIX,  ;  on
              Windows).

       JAVAC  The Java compiler.

       JAVACCOM
              The  command  line used to compile a directory tree containing Java source files to
              corresponding  Java  class  files.   Any  options  specified  in  the   $JAVACFLAGS
              construction variable are included on this command line.

       JAVACCOMSTR
              The  string  displayed  when  compiling  a  directory  tree of Java source files to
              corresponding Java class files.  If this is not set, then  $JAVACCOM  (the  command
              line) is displayed.

              env = Environment(JAVACCOMSTR = "Compiling class files $TARGETS from $SOURCES")

       JAVACFLAGS
              General options that are passed to the Java compiler.

       JAVACLASSDIR
              The  directory  in  which Java class files may be found.  This is stripped from the
              beginning of any Java .class file names supplied to the JavaH builder.

       JAVACLASSPATH
              Specifies the list of directories that will be searched for Java .class file.   The
              directories in this list will be added to the &javac; and &javah; command lines via
              the -classpath option.  The individual directory names will  be  separated  by  the
              operating system's path separate character (: on UNIX/Linux/POSIX, ; on Windows).

              Note  that  this  currently  just  adds  the specified directory via the -classpath
              option.  &SCons; does not  currently  search  the  $JAVACLASSPATH  directories  for
              dependency .class files.

       JAVACLASSSUFFIX
              The suffix for Java class files; .class by default.

       JAVAH  The Java generator for C header and stub files.

       JAVAHCOM
              The  command  line used to generate C header and stub files from Java classes.  Any
              options specified in the $JAVAHFLAGS construction variable  are  included  on  this
              command line.

       JAVAHCOMSTR
              The  string displayed when C header and stub files are generated from Java classes.
              If this is not set, then $JAVAHCOM (the command line) is displayed.

              env = Environment(JAVAHCOMSTR = "Generating header/stub file(s) $TARGETS from $SOURCES")

       JAVAHFLAGS
              General options passed to the C header and stub file generator for Java classes.

       JAVASOURCEPATH
              Specifies the list of directories that will be searched for input .java file.   The
              directories  in  this  list  will  be  added  to  the  &javac; command line via the
              -sourcepath option.  The individual  directory  names  will  be  separated  by  the
              operating system's path separate character (: on UNIX/Linux/POSIX, ; on Windows).

              Note  that  this  currently  just  adds the specified directory via the -sourcepath
              option.  &SCons; does not currently  search  the  $JAVASOURCEPATH  directories  for
              dependency .java files.

       JAVASUFFIX
              The suffix for Java files; .java by default.

       JAVAVERSION
              Specifies the Java version being used by the Java() builder.  This is not currently
              used to select one version of the Java compiler vs. another.  Instead,  you  should
              set  this  to  specify the version of Java supported by your &javac; compiler.  The
              default is 1.4.

              This is sometimes necessary because Java  1.5  changed  the  file  names  that  are
              created  for  nested  anonymous  inner classes, which can cause a mismatch with the
              files that &SCons; expects will be generated  by  the  &javac;  compiler.   Setting
              $JAVAVERSION  to  1.5 (or 1.6, as appropriate) can make &SCons; realize that a Java
              1.5 or 1.6 build is actually up to date.

       LATEX  The LaTeX structured formatter and typesetter.

       LATEXCOM
              The command line used to call the LaTeX structured formatter and typesetter.

       LATEXCOMSTR
              The string displayed when calling the LaTeX structured  formatter  and  typesetter.
              If this is not set, then $LATEXCOM (the command line) is displayed.

              env = Environment(LATEXCOMSTR = "Building $TARGET from LaTeX input $SOURCES")

       LATEXFLAGS
              General options passed to the LaTeX structured formatter and typesetter.

       LATEXRETRIES
              The  maximum number of times that LaTeX will be re-run if the .log generated by the
              $LATEXCOM command indicates that there are undefined references.  The default is to
              try to resolve undefined references by re-running LaTeX up to three times.

       LATEXSUFFIXES
              The  list of suffixes of files that will be scanned for LaTeX implicit dependencies
              (\include or \import files).  The default list is:

              [".tex", ".ltx", ".latex"]

       LDMODULE
              The linker for building loadable modules.  By default, this is the same as $SHLINK.

       LDMODULECOM
              The command line for building loadable  modules.   On  Mac  OS  X,  this  uses  the
              $LDMODULE,  $LDMODULEFLAGS  and $FRAMEWORKSFLAGS variables.  On other systems, this
              is the same as $SHLINK.

       LDMODULECOMSTR
              The string displayed when building loadable modules.  If  this  is  not  set,  then
              $LDMODULECOM (the command line) is displayed.

       LDMODULEFLAGS
              General user options passed to the linker for building loadable modules.

       LDMODULEPREFIX
              The  prefix  used  for  loadable  module file names.  On Mac OS X, this is null; on
              other systems, this is the same as $SHLIBPREFIX.

       LDMODULESUFFIX
              The suffix used for loadable module file names.  On Mac OS  X,  this  is  null;  on
              other systems, this is the same as $SHLIBSUFFIX.

       LEX    The lexical analyzer generator.

       LEXCOM The  command  line used to call the lexical analyzer generator to generate a source
              file.

       LEXCOMSTR
              The string displayed when generating a  source  file  using  the  lexical  analyzer
              generator.  If this is not set, then $LEXCOM (the command line) is displayed.

              env = Environment(LEXCOMSTR = "Lex'ing $TARGET from $SOURCES")

       LEXFLAGS
              General options passed to the lexical analyzer generator.

       _LIBDIRFLAGS
              An automatically-generated construction variable containing the linker command-line
              options for specifying directories to  be  searched  for  library.   The  value  of
              $_LIBDIRFLAGS  is  created  by  appending  $LIBDIRPREFIX  and  $LIBDIRSUFFIX to the
              beginning and end of each directory in $LIBPATH.

       LIBDIRPREFIX
              The prefix used to specify a library directory on the linker  command  line.   This
              will  be  appended  to the beginning of each directory in the $LIBPATH construction
              variable when the $_LIBDIRFLAGS variable is automatically generated.

       LIBDIRSUFFIX
              The suffix used to specify a library directory on the linker  command  line.   This
              will be appended to the end of each directory in the $LIBPATH construction variable
              when the $_LIBDIRFLAGS variable is automatically generated.

       LIBEMITTER
              TODO

       _LIBFLAGS
              An automatically-generated construction variable containing the linker command-line
              options for specifying libraries to be linked with the resulting target.  The value
              of $_LIBFLAGS is created by appending  $LIBLINKPREFIX  and  $LIBLINKSUFFIX  to  the
              beginning and end of each filename in $LIBS.

       LIBLINKPREFIX
              The prefix used to specify a library to link on the linker command line.  This will
              be appended to the beginning of each library in  the  $LIBS  construction  variable
              when the $_LIBFLAGS variable is automatically generated.

       LIBLINKSUFFIX
              The suffix used to specify a library to link on the linker command line.  This will
              be appended to the end of each library in the $LIBS construction variable when  the
              $_LIBFLAGS variable is automatically generated.

       LIBPATH
              The  list  of  directories  that  will  be  searched  for  libraries.  The implicit
              dependency  scanner  will  search  these  directories  for  include  files.   Don't
              explicitly  put  include  directory arguments in $LINKFLAGS or $SHLINKFLAGS because
              the result will be non-portable and the directories will not  be  searched  by  the
              dependency  scanner. Note: directory names in LIBPATH will be looked-up relative to
              the SConscript directory when they are used in a command. To force scons to look-up
              a directory relative to the root of the source tree use #:

              env = Environment(LIBPATH='#/libs')

              The directory look-up can also be forced using the Dir() function:

              libs = Dir('libs')
              env = Environment(LIBPATH=libs)

              The  directory  list  will  be  added  to  command lines through the automatically-
              generated $_LIBDIRFLAGS construction variable, which is  constructed  by  appending
              the  values  of  the  $LIBDIRPREFIXand$LIBDIRSUFFIX  construction  variables to the
              beginning and end of each directory in $LIBPATH.  Any command lines you define that
              need the LIBPATH directory list should include $_LIBDIRFLAGS:

              env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

       LIBPREFIX
              The  prefix  used for (static) library file names.  A default value is set for each
              platform (posix, win32, os2, etc.), but the value is overridden by individual tools
              (ar,  mslib,  sgiar, sunar, tlib, etc.)  to reflect the names of the libraries they
              create.

       LIBPREFIXES
              A list of all legal prefixes for library file names.  When  searching  for  library
              dependencies, SCons will look for files with these prefixes, the base library name,
              and suffixes in the $LIBSUFFIXES list.

       LIBS   A list of one or more libraries that will be linked with  any  executable  programs
              created by this environment.

              The library list will be added to command lines through the automatically-generated
              $_LIBFLAGS construction variable, which is constructed by appending the  values  of
              the $LIBLINKPREFIXand$LIBLINKSUFFIX construction variables to the beginning and end
              of each filename in $LIBS.  Any command lines you define that need the LIBS library
              list should include $_LIBFLAGS:

              env = Environment(LINKCOM="my_linker $_LIBDIRFLAGS $_LIBFLAGS -o $TARGET $SOURCE")

              If  you add a File object to the $LIBS list, the name of that file will be added to
              $_LIBFLAGS,  and  thus  the  link  line,   as   is,   without   $LIBLINKPREFIX   or
              $LIBLINKSUFFIX.  For example:

              env.Append(LIBS=File('/tmp/mylib.so'))

              In  all  cases,  scons will add dependencies from the executable program to all the
              libraries in this list.

       LIBSUFFIX
              The suffix used for (static) library file names.  A default value is set  for  each
              platform (posix, win32, os2, etc.), but the value is overridden by individual tools
              (ar, mslib, sgiar, sunar, tlib, etc.)  to reflect the names of the  libraries  they
              create.

       LIBSUFFIXES
              A  list  of  all legal suffixes for library file names.  When searching for library
              dependencies, SCons will look for files with prefixes, in  the  $LIBPREFIXES  list,
              the base library name, and these suffixes.

       LICENSE
              The  abbreviated  name  of  the  license under which this project is released (gpl,
              lpgl, bsd etc.).  See http://www.opensource.org/licenses/alphabetical for a list of
              license names.

       LINESEPARATOR
              The  separator used by the Substfile() and Textfile() builders.  This value is used
              between sources when constructing the target.  It defaults to  the  current  system
              line separator.

       LINK   The linker.

       LINKCOM
              The command line used to link object files into an executable.

       LINKCOMSTR
              The  string  displayed when object files are linked into an executable.  If this is
              not set, then $LINKCOM (the command line) is displayed.

              env = Environment(LINKCOMSTR = "Linking $TARGET")

       LINKFLAGS
              General user options passed to the linker.  Note  that  this  variable  should  not
              contain -l (or similar) options for linking with the libraries listed in $LIBS, nor
              -L (or similar) library search path options that scons generates automatically from
              $LIBPATH.   See  $_LIBFLAGS  above,  for  the variable that expands to library-link
              options, and $_LIBDIRFLAGS above, for the variable that expands to  library  search
              path options.

       M4     The M4 macro preprocessor.

       M4COM  The command line used to pass files through the M4 macro preprocessor.

       M4COMSTR
              The  string  displayed when a file is passed through the M4 macro preprocessor.  If
              this is not set, then $M4COM (the command line) is displayed.

       M4FLAGS
              General options passed to the M4 macro preprocessor.

       MAKEINDEX
              The makeindex generator  for  the  TeX  formatter  and  typesetter  and  the  LaTeX
              structured formatter and typesetter.

       MAKEINDEXCOM
              The  command  line  used  to call the makeindex generator for the TeX formatter and
              typesetter and the LaTeX structured formatter and typesetter.

       MAKEINDEXCOMSTR
              The string displayed when calling the makeindex generator for the TeX formatter and
              typesetter  and the LaTeX structured formatter and typesetter.  If this is not set,
              then $MAKEINDEXCOM (the command line) is displayed.

       MAKEINDEXFLAGS
              General options passed to  the  makeindex  generator  for  the  TeX  formatter  and
              typesetter and the LaTeX structured formatter and typesetter.

       MAXLINELENGTH
              The  maximum  number  of  characters allowed on an external command line.  On Win32
              systems, link lines longer than this many characters are  linked  via  a  temporary
              file name.

       MIDL   The Microsoft IDL compiler.

       MIDLCOM
              The command line used to pass files to the Microsoft IDL compiler.

       MIDLCOMSTR
              The  string  displayed  when  the Microsoft IDL copmiler is called.  If this is not
              set, then $MIDLCOM (the command line) is displayed.

       MIDLFLAGS
              General options passed to the Microsoft IDL compiler.

       MSSDK_DIR
              The directory containing the Microsoft SDK (either Platform SDK or Windows SDK)  to
              be used for compilation.

       MSSDK_VERSION
              The  version string of the Microsoft SDK (either Platform SDK or Windows SDK) to be
              used for compilation.  Supported  versions  include  6.1,  6.0A,  6.0,  2003R2  and
              2003R1.

       MSVC_BATCH
              When set to any true value, specifies that SCons should batch compilation of object
              files when calling the Microsoft Visual C/C++ compiler.  All compilations of source
              files  from  the  same source directory that generate target files in a same output
              directory and were configured in SCons using the same construction environment will
              be  built  in  a  single call to the compiler.  Only source files that have changed
              since their object files were built will be passed to each compiler invocation (via
              the  $CHANGED_SOURCES  construction  variable).   Any compilations where the object
              (target) file base name (minus the .obj) does not match the source file  base  name
              will be compiled separately.

       MSVC_USE_SCRIPT
              Use a batch script to set up Microsoft Visual Studio compiler

              $MSVC_USE_SCRIPToverrides$MSVC_VERSIONand$TARGET_ARCH.   If  set  to  the name of a
              Visual Studio .bat file (e.g. vcvars.bat), SCons will run that bat file and extract
              the  relevant  variables  from the result (typically %INCLUDE%, %LIB%, and %PATH%).
              Setting MSVC_USE_SCRIPT to None bypasses the Visual Studio autodetection  entirely;
              use  this  if you are running SCons in a Visual Studio cmd window and importing the
              shell's environment variables.

       MSVC_VERSION
              Sets the preferred  version of Microsoft Visual C/C++ to use.

              If $MSVC_VERSION is not set, SCons will (by default) select the latest  version  of
              Visual  C/C++  installed on your system.  If the specified version isn't installed,
              tool initialization will fail.  This variable must be passed as an argument to  the
              Environment() constructor; setting it later has no effect.  Set it to an unexpected
              value (e.g. "XXX") to see the valid values on your system.

       MSVS   When the Microsoft Visual Studio tools are initialized, they set up this dictionary
              with the following keys:

              VERSION: the version of MSVS being used (can be set via $MSVS_VERSION)

              VERSIONS: the available versions of MSVS installed

              VCINSTALLDIR: installed directory of Visual C++

              VSINSTALLDIR: installed directory of Visual Studio

              FRAMEWORKDIR: installed directory of the .NET framework

              FRAMEWORKVERSIONS:  list of installed versions of the .NET framework, sorted latest
              to oldest.

              FRAMEWORKVERSION: latest installed version of the .NET framework

              FRAMEWORKSDKDIR: installed location of the .NET SDK.

              PLATFORMSDKDIR: installed location of the Platform SDK.

              PLATFORMSDK_MODULES: dictionary  of  installed  Platform  SDK  modules,  where  the
              dictionary  keys  are keywords for the various modules, and the values are 2-tuples
              where the first is the release date, and the second is the version number.

              If a value isn't set, it wasn't available in the registry.

       MSVS_ARCH
              Sets the architecture for which the generated project(s) should build.

              The default value is x86.  amd64 is also  supported  by  &SCons;  for  some  Visual
              Studio  versions.  Trying to set $MSVS_ARCH to an architecture that's not supported
              for a given Visual Studio version will generate an error.

       MSVS_PROJECT_GUID
              The string placed in a generated Microsoft Visual Studio project file as the  value
              of  the  ProjectGUID  attribute.   There is no default value. If not defined, a new
              GUID is generated.

       MSVS_SCC_AUX_PATH
              The path name placed in a generated Microsoft Visual Studio  project  file  as  the
              value of the SccAuxPath attribute if the MSVS_SCC_PROVIDER construction variable is
              also set.  There is no default value.

       MSVS_SCC_CONNECTION_ROOT
              The root path of projects in your SCC workspace,  i.e  the  path  under  which  all
              project  and  solution files will be generated. It is used as a reference path from
              which the relative paths of the  generated  Microsoft  Visual  Studio  project  and
              solution files are computed.  The relative project file path is placed as the value
              of the SccLocalPath attribute of  the  project  file  and  as  the  values  of  the
              SccProjectFilePathRelativizedFromConnection[i]  (where  [i]  ranges  from  0 to the
              number    of    projects     in     the     solution)     attributes     of     the
              GlobalSection(SourceCodeControl)  section  of  the Microsoft Visual Studio solution
              file.  Similarly the relative solution file path is placed as  the  values  of  the
              SccLocalPath[i] (where [i] ranges from 0 to the number of projects in the solution)
              attributes of the GlobalSection(SourceCodeControl) section of the Microsoft  Visual
              Studio  solution  file.   This  is  used only if the MSVS_SCC_PROVIDER construction
              variable is also set.  The default value is the current working directory.

       MSVS_SCC_PROJECT_NAME
              The project name placed in a generated Microsoft Visual Studio project file as  the
              value  of  the  SccProjectName  attribute  if  the  MSVS_SCC_PROVIDER  construction
              variable  is  also  set.   In  this  case  the  string  is  also  placed   in   the
              SccProjectName0  attribute  of  the GlobalSection(SourceCodeControl) section of the
              Microsoft Visual Studio solution file.  There is no default value.

       MSVS_SCC_PROVIDER
              The string placed in a generated Microsoft Visual Studio project file as the  value
              of  the  SccProvider  attribute.   The  string  is  also placed in the SccProvider0
              attribute of the GlobalSection(SourceCodeControl) section of the  Microsoft  Visual
              Studio solution file.  There is no default value.

       MSVS_VERSION
              Sets the preferred version of Microsoft Visual Studio to use.

              If $MSVS_VERSION is not set, &SCons; will (by default) select the latest version of
              Visual Studio installed on your system.  So, if you have version 6  and  version  7
              (MSVS  .NET)  installed,  it  will  prefer  version  7.   You  can override this by
              specifying the MSVS_VERSION variable in the Environment initialization, setting  it
              to the appropriate version ('6.0' or '7.0', for example).  If the specified version
              isn't installed, tool initialization will fail.

              This  is  obsolete:  use  $MSVC_VERSION  instead.  If  $MSVS_VERSION  is  set   and
              $MSVC_VERSIONisnot,$MSVC_VERSIONwillbesetautomaticallyto$MSVS_VERSION.  If both are
              set to different values, scons will raise an error.

       MSVSBUILDCOM
              The build command line placed in a generated Microsoft Visual Studio project  file.
              The default is to have Visual Studio invoke SCons with any specified build targets.

       MSVSCLEANCOM
              The  clean command line placed in a generated Microsoft Visual Studio project file.
              The default is to have Visual Studio invoke SCons with the -c option to remove  any
              specified targets.

       MSVSENCODING
              The  encoding  string  placed  in a generated Microsoft Visual Studio project file.
              The default is encoding Windows-1252.

       MSVSPROJECTCOM
              The action used to generate Microsoft Visual Studio project files.

       MSVSPROJECTSUFFIX
              The suffix used for Microsoft Visual Studio project (DSP) files.  The default value
              is  .vcproj  when using Visual Studio version 7.x (.NET) or later version, and .dsp
              when using earlier versions of Visual Studio.

       MSVSREBUILDCOM
              The rebuild command line placed in a  generated  Microsoft  Visual  Studio  project
              file.  The default is to have Visual Studio invoke SCons with any specified rebuild
              targets.

       MSVSSCONS
              The SCons used in generated Microsoft Visual Studio project files.  The default  is
              the version of SCons being used to generate the project file.

       MSVSSCONSCOM
              The default SCons command used in generated Microsoft Visual Studio project files.

       MSVSSCONSCRIPT
              The  sconscript  file (that is, SConstruct or SConscript file) that will be invoked
              by Visual Studio project files (through the $MSVSSCONSCOM variable).   The  default
              is  the  same  sconscript file that contains the call to MSVSProject() to build the
              project file.

       MSVSSCONSFLAGS
              The SCons flags used in generated Microsoft Visual Studio project files.

       MSVSSOLUTIONCOM
              The action used to generate Microsoft Visual Studio solution files.

       MSVSSOLUTIONSUFFIX
              The suffix used for Microsoft Visual Studio  solution  (DSW)  files.   The  default
              value  is  .sln  when  using  Visual Studio version 7.x (.NET), and .dsw when using
              earlier versions of Visual Studio.

       MT     The program used on Windows systems to embed manifests into  DLLs  and  EXEs.   See
              also $WINDOWS_EMBED_MANIFEST.

       MTEXECOM
              The  Windows  command  line  used  to  embed  manifests into executables.  See also
              $MTSHLIBCOM.

       MTFLAGS
              Flags passed to the $MT manifest embedding program (Windows only).

       MTSHLIBCOM
              The Windows command line used to embed manifests into shared libraries (DLLs).  See
              also $MTEXECOM.

       MWCW_VERSION
              The version number of the MetroWerks CodeWarrior C compiler to be used.

       MWCW_VERSIONS
              A  list  of  installed  versions  of  the MetroWerks CodeWarrior C compiler on this
              system.

       NAME   Specfies the name of the project to package.

       no_import_lib
              When set to non-zero, suppresses creation of a corresponding Windows static  import
              lib  by  the SharedLibrary builder when used with MinGW, Microsoft Visual Studio or
              Metrowerks.  This also suppresses creation of an  export  (.exp)  file  when  using
              Microsoft Visual Studio.

       OBJPREFIX
              The prefix used for (static) object file names.

       OBJSUFFIX
              The suffix used for (static) object file names.

       P4     The Perforce executable.

       P4COM  The command line used to fetch source files from Perforce.

       P4COMSTR
              The  string  displayed  when  fetching a source file from Perforce.  If this is not
              set, then $P4COM (the command line) is displayed.

       P4FLAGS
              General options that are passed to Perforce.

       PACKAGEROOT
              Specifies the directory where all files in resulting  archive  will  be  placed  if
              applicable.  The default value is "$NAME-$VERSION".

       PACKAGETYPE
              Selects the package type to build.  Currently these are available:

               * msi - Microsoft Installer
               * rpm - Redhat Package Manger
               * ipkg - Itsy Package Management System
               * tarbz2 - compressed tar
               * targz - compressed tar
               * zip - zip file
               * src_tarbz2 - compressed tar source
               * src_targz - compressed tar source
               * src_zip - zip file source

              This may be overridden with the "package_type" command line option.

       PACKAGEVERSION
              The  version  of  the package (not the underlying project).  This is currently only
              used by the rpm packager and should reflect  changes  in  the  packaging,  not  the
              underlying project code itself.

       PCH    The Microsoft Visual C++ precompiled header that will be used when compiling object
              files. This variable is ignored by tools other than  Microsoft  Visual  C++.   When
              this  variable  is  defined  SCons will add options to the compiler command line to
              cause it to use the precompiled header, and will also set up the  dependencies  for
              the PCH file.  Example:

              env['PCH'] = 'StdAfx.pch'

       PCHCOM The command line used by the PCH() builder to generated a precompiled header.

       PCHCOMSTR
              The  string  displayed  when  generating a precompiled header.  If this is not set,
              then $PCHCOM (the command line) is displayed.

       PCHPDBFLAGS
              A construction variable that, when expanded, adds the /yD flag to the command  line
              only if the $PDB construction variable is set.

       PCHSTOP
              This  variable specifies how much of a source file is precompiled. This variable is
              ignored by tools other than Microsoft Visual C++, or when the PCH variable  is  not
              being  used.  When  this variable is define it must be a string that is the name of
              the header that is included at the end of the precompiled  portion  of  the  source
              files, or the empty string if the "#pragma hrdstop" construct is being used:

              env['PCHSTOP'] = 'StdAfx.h'

       PDB    The  Microsoft Visual C++ PDB file that will store debugging information for object
              files, shared libraries, and programs. This variable is ignored by tools other than
              Microsoft  Visual C++.  When this variable is defined SCons will add options to the
              compiler and linker command line to  cause  them  to  generate  external  debugging
              information, and will also set up the dependencies for the PDB file.  Example:

              env['PDB'] = 'hello.pdb'

              The  Visual  C++  compiler  switch  that  SCons  uses  by  default  to generate PDB
              information is /Z7.  This works correctly with  parallel  (-j)  builds  because  it
              embeds  the  debug  information  in  the  intermediate  object files, as opposed to
              sharing a single PDB file between multiple object files.  This is also the only way
              to get debug information embedded into a static library.  Using the /Zi instead may
              yield improved link-time performance, although parallel builds will no longer work.
              You  can  generate  PDB  files  with  the  /Zi  switch  by  overriding  the default
              $CCPDBFLAGS variable; see the entry for that variable for specific examples.

       PDFCOM A deprecated synonym for $DVIPDFCOM.

       PDFLATEX
              The &pdflatex; utility.

       PDFLATEXCOM
              The command line used to call the &pdflatex; utility.

       PDFLATEXCOMSTR
              The string displayed when calling the &pdflatex; utility.  If this is not set, then
              $PDFLATEXCOM (the command line) is displayed.

              env = Environment(PDFLATEX;COMSTR = "Building $TARGET from LaTeX input $SOURCES")

       PDFLATEXFLAGS
              General options passed to the &pdflatex; utility.

       PDFPREFIX
              The prefix used for PDF file names.

       PDFSUFFIX
              The suffix used for PDF file names.

       PDFTEX The &pdftex; utility.

       PDFTEXCOM
              The command line used to call the &pdftex; utility.

       PDFTEXCOMSTR
              The  string  displayed when calling the &pdftex; utility.  If this is not set, then
              $PDFTEXCOM (the command line) is displayed.

              env = Environment(PDFTEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

       PDFTEXFLAGS
              General options passed to the &pdftex; utility.

       PKGCHK On Solaris systems, the package-checking program that  will  be  used  (along  with
              $PKGINFO)  to look for installed versions of the Sun PRO C++ compiler.  The default
              is /usr/sbin/pgkchk.

       PKGINFO
              On Solaris systems, the package information program that will be used  (along  with
              $PKGCHK)  to  look for installed versions of the Sun PRO C++ compiler.  The default
              is pkginfo.

       PLATFORM
              The name of the platform used  to  create  the  Environment.   If  no  platform  is
              specified when the Environment is created, scons autodetects the platform.

              env = Environment(tools = [])
              if env['PLATFORM'] == 'cygwin':
                  Tool('mingw')(env)
              else:
                  Tool('msvc')(env)

       PRINT_CMD_LINE_FUNC
              A  Python  function  used to print the command lines as they are executed (assuming
              command printing is not disabled by the -q or -s  options  or  their  equivalents).
              The  function should take four arguments: s, the command being executed (a string),
              target, the target being built (file node, list, or string  name(s)),  source,  the
              source(s) used (file node, list, or string name(s)), and env, the environment being
              used.

              The function must do the printing itself.  The default implementation, used if this
              variable is not set or is None, is:
              def print_cmd_line(s, target, source, env):
                sys.stdout.write(s + "\n")

              Here's an example of a more interesting function:

              def print_cmd_line(s, target, source, env):
                 sys.stdout.write("Building %s -> %s...\n" %
                  (' and '.join([str(x) for x in source]),
                   ' and '.join([str(x) for x in target])))
              env=Environment(PRINT_CMD_LINE_FUNC=print_cmd_line)
              env.Program('foo', 'foo.c')

              This  just  prints  "Building  targetname from sourcename..." instead of the actual
              commands.  Such a function could also log the actual commands to a  log  file,  for
              example.

       PROGEMITTER
              TODO

       PROGPREFIX
              The prefix used for executable file names.

       PROGSUFFIX
              The suffix used for executable file names.

       PSCOM  The command line used to convert TeX DVI files into a PostScript file.

       PSCOMSTR
              The  string  displayed when a TeX DVI file is converted into a PostScript file.  If
              this is not set, then $PSCOM (the command line) is displayed.

       PSPREFIX
              The prefix used for PostScript file names.

       PSSUFFIX
              The prefix used for PostScript file names.

       QT_AUTOSCAN
              Turn off scanning for mocable files. Use the  Moc  Builder  to  explicitly  specify
              files to run moc on.

       QT_BINPATH
              The path where the qt binaries are installed.  The default value is '$QTDIR/bin'.

       QT_CPPPATH
              The  path  where  the  qt  header  files  are  installed.   The  default  value  is
              '$QTDIR/include'.  Note: If you set this variable to None, the  tool  won't  change
              the $CPPPATH construction variable.

       QT_DEBUG
              Prints lots of debugging information while scanning for moc files.

       QT_LIB Default  value  is 'qt'. You may want to set this to 'qt-mt'. Note: If you set this
              variable to None, the tool won't change the $LIBS variable.

       QT_LIBPATH
              The path where the qt libraries are installed.  The default value is  '$QTDIR/lib'.
              Note:  If  you  set  this  variable  to  None,  the  tool won't change the $LIBPATH
              construction variable.

       QT_MOC Default value is '$QT_BINPATH/moc'.

       QT_MOCCXXPREFIX
              Default value is ''. Prefix for moc output files, when source is a cxx file.

       QT_MOCCXXSUFFIX
              Default value is '.moc'. Suffix for moc output files, when source is a cxx file.

       QT_MOCFROMCXXCOM
              Command to generate a moc file from a cpp file.

       QT_MOCFROMCXXCOMSTR
              The string displayed when generating a moc file from a cpp file.  If  this  is  not
              set, then $QT_MOCFROMCXXCOM (the command line) is displayed.

       QT_MOCFROMCXXFLAGS
              Default value is '-i'. These flags are passed to moc, when moccing a C++ file.

       QT_MOCFROMHCOM
              Command to generate a moc file from a header.

       QT_MOCFROMHCOMSTR
              The  string  displayed  when generating a moc file from a cpp file.  If this is not
              set, then $QT_MOCFROMHCOM (the command line) is displayed.

       QT_MOCFROMHFLAGS
              Default value is ''. These flags are passed to moc, when moccing a header file.

       QT_MOCHPREFIX
              Default value is 'moc_'. Prefix for moc output files, when source is a header.

       QT_MOCHSUFFIX
              Default value is '$CXXFILESUFFIX'. Suffix for moc output files, when  source  is  a
              header.

       QT_UIC Default value is '$QT_BINPATH/uic'.

       QT_UICCOM
              Command to generate header files from .ui files.

       QT_UICCOMSTR
              The  string  displayed when generating header files from .ui files.  If this is not
              set, then $QT_UICCOM (the command line) is displayed.

       QT_UICDECLFLAGS
              Default value is ''. These flags are passed to uic, when creating a a h file from a
              .ui file.

       QT_UICDECLPREFIX
              Default value is ''. Prefix for uic generated header files.

       QT_UICDECLSUFFIX
              Default value is '.h'. Suffix for uic generated header files.

       QT_UICIMPLFLAGS
              Default value is ''. These flags are passed to uic, when creating a cxx file from a
              .ui file.

       QT_UICIMPLPREFIX
              Default value is 'uic_'. Prefix for uic generated implementation files.

       QT_UICIMPLSUFFIX
              Default value is '$CXXFILESUFFIX'. Suffix for uic generated implementation files.

       QT_UISUFFIX
              Default value is '.ui'. Suffix of designer input files.

       QTDIR  The qt tool tries to take this from  os.environ.   It  also  initializes  all  QT_*
              construction  variables  listed  below.   (Note that all paths are constructed with
              python's os.path.join() method, but are listed here  with  the  '/'  separator  for
              easier  reading.)   In  addition,  the construction environment variables $CPPPATH,
              $LIBPATH    and     $LIBS     may     be     modified     and     the     variables
              $PROGEMITTER,$SHLIBEMITTERand$LIBEMITTER   are   modified.   Because   the   build-
              performance is affected when using this tool, you have to explicitly specify it  at
              Environment creation:

              Environment(tools=['default','qt'])

              The qt tool supports the following operations:

              Automatic  moc  file  generation from header files.  You do not have to specify moc
              files explicitly, the tool does it for you.  However, there are a few preconditions
              to  do so: Your header file must have the same filebase as your implementation file
              and must stay in the same directory. It must have one of the suffixes .h, .hpp, .H,
              .hxx, .hh. You can turn off automatic moc file generation by setting QT_AUTOSCAN to
              0.  See also the corresponding Moc()() builder method.

              Automatic moc file generation from cxx files.  As stated in the  qt  documentation,
              include  the moc file at the end of the cxx file. Note that you have to include the
              file,       which       is       generated       by       the        transformation
              ${QT_MOCCXXPREFIX}<basename>${QT_MOCCXXSUFFIX},   by   default   <basename>.moc.  A
              warning is generated after building the moc file, if you do not include the correct
              file.  If  you  are  using VariantDir, you may need to specify duplicate=1. You can
              turn off automatic moc file generation by setting QT_AUTOSCAN to 0.  See  also  the
              corresponding Moc() builder method.

              Automatic handling of .ui files.  The implementation files generated from .ui files
              are handled much the same as yacc or lex files. Each .ui file given as a source  of
              Program,  Library or SharedLibrary will generate three files, the declaration file,
              the implementation file and a moc file. Because there are also  generated  headers,
              you  may  need  to  specify  duplicate=1  in  calls  to  VariantDir.   See also the
              corresponding Uic() builder method.

       RANLIB The archive indexer.

       RANLIBCOM
              The command line used to index a static library archive.

       RANLIBCOMSTR
              The string displayed when a static library archive is indexed.  If this is not set,
              then $RANLIBCOM (the command line) is displayed.

              env = Environment(RANLIBCOMSTR = "Indexing $TARGET")

       RANLIBFLAGS
              General options passed to the archive indexer.

       RC     The resource compiler used to build a Microsoft Visual C++ resource file.

       RCCOM  The command line used to build a Microsoft Visual C++ resource file.

       RCCOMSTR
              The  string  displayed  when  invoking  the  resource compiler to build a Microsoft
              Visual C++ resource file.  If this is not set, then $RCCOM (the  command  line)  is
              displayed.

       RCFLAGS
              The flags passed to the resource compiler by the RES builder.

       RCINCFLAGS
              An   automatically-generated  construction  variable  containing  the  command-line
              options for specifying directories to be searched by the  resource  compiler.   The
              value  of  $RCINCFLAGS is created by appending $RCINCPREFIX and $RCINCSUFFIX to the
              beginning and end of each directory in $CPPPATH.

       RCINCPREFIX
              The prefix (flag) used to specify an include directory  on  the  resource  compiler
              command  line.   This  will  be  appended to the beginning of each directory in the
              $CPPPATH construction variable when the $RCINCFLAGS variable is expanded.

       RCINCSUFFIX
              The suffix used to specify an include directory on the  resource  compiler  command
              line.   This  will  be  appended  to  the  end  of  each  directory in the $CPPPATH
              construction variable when the $RCINCFLAGS variable is expanded.

       RCS    The RCS executable.  Note that this variable is not actually used for  the  command
              to fetch source files from RCS; see the $RCS_CO construction variable, below.

       RCS_CO The RCS "checkout" executable, used to fetch source files from RCS.

       RCS_COCOM
              The command line used to fetch (checkout) source files from RCS.

       RCS_COCOMSTR
              The  string  displayed  when  fetching a source file from RCS.  If this is not set,
              then $RCS_COCOM (the command line) is displayed.

       RCS_COFLAGS
              Options that are passed to the $RCS_CO command.

       RDirs  A function that converts a string into a list of Dir  instances  by  searching  the
              repositories.

       REGSVR The  program used on Windows systems to register a newly-built DLL library whenever
              the SharedLibrary() builder is passed a keyword argument of register=1.

       REGSVRCOM
              The command line used on Windows systems to  register  a  newly-built  DLL  library
              whenever the SharedLibrary() builder is passed a keyword argument of register=1.

       REGSVRCOMSTR
              The  string displayed when registering a newly-built DLL file.  If this is not set,
              then $REGSVRCOM (the command line) is displayed.

       REGSVRFLAGS
              Flags passed to the DLL registration program on Windows systems when a  newly-built
              DLL  library  is registered.  By default, this includes the /s that prevents dialog
              boxes from popping up and requiring user attention.

       RMIC   The Java RMI stub compiler.

       RMICCOM
              The command line used to compile stub and skeleton class files  from  Java  classes
              that  contain  RMI  implementations.   Any  options  specified  in  the  $RMICFLAGS
              construction variable are included on this command line.

       RMICCOMSTR
              The string displayed when compiling stub and skeleton class files from Java classes
              that  contain  RMI implementations.  If this is not set, then $RMICCOM (the command
              line) is displayed.

              env = Environment(RMICCOMSTR = "Generating stub/skeleton class files $TARGETS from $SOURCES")

       RMICFLAGS
              General options passed to the Java RMI stub compiler.

       _RPATH An automatically-generated construction variable containing the rpath flags  to  be
              used when linking a program with shared libraries.  The value of $_RPATH is created
              by appending $RPATHPREFIX and  $RPATHSUFFIX  to  the  beginning  and  end  of  each
              directory in $RPATH.

       RPATH  A  list  of  paths to search for shared libraries when running programs.  Currently
              only used in the GNU (gnulink), IRIX (sgilink) and Sun (sunlink) linkers.   Ignored
              on  platforms  and  toolchains that don't support it.  Note that the paths added to
              RPATH are not transformed by scons in any way:  if you want an absolute  path,  you
              must make it absolute yourself.

       RPATHPREFIX
              The  prefix  used  to  specify a directory to be searched for shared libraries when
              running programs.  This will be appended to the beginning of each directory in  the
              $RPATH construction variable when the $_RPATH variable is automatically generated.

       RPATHSUFFIX
              The  suffix  used  to  specify a directory to be searched for shared libraries when
              running programs.  This will be appended to the end of each directory in the $RPATH
              construction variable when the $_RPATH variable is automatically generated.

       RPCGEN The RPC protocol compiler.

       RPCGENCLIENTFLAGS
              Options  passed  to  the  RPC  protocol compiler when generating client side stubs.
              These are in addition to any  flags  specified  in  the  $RPCGENFLAGS  construction
              variable.

       RPCGENFLAGS
              General options passed to the RPC protocol compiler.

       RPCGENHEADERFLAGS
              Options  passed  to the RPC protocol compiler when generating a header file.  These
              are in addition to any flags specified in the $RPCGENFLAGS construction variable.

       RPCGENSERVICEFLAGS
              Options passed to the RPC protocol compiler  when  generating  server  side  stubs.
              These  are  in  addition  to  any  flags specified in the $RPCGENFLAGS construction
              variable.

       RPCGENXDRFLAGS
              Options passed to the RPC protocol compiler when generating  XDR  routines.   These
              are in addition to any flags specified in the $RPCGENFLAGS construction variable.

       SCANNERS
              A  list  of  the  available implicit dependency scanners.  New file scanners may be
              added by appending to  this  list,  although  the  more  flexible  approach  is  to
              associate scanners with a specific Builder.  See the sections "Builder Objects" and
              "Scanner Objects," below, for more information.

       SCCS   The SCCS executable.

       SCCSCOM
              The command line used to fetch source files from SCCS.

       SCCSCOMSTR
              The string displayed when fetching a source file from a CVS repository.  If this is
              not set, then $SCCSCOM (the command line) is displayed.

       SCCSFLAGS
              General options that are passed to SCCS.

       SCCSGETFLAGS
              Options  that  are  passed  specifically to the SCCS "get" subcommand.  This can be
              set, for example, to -e to check out editable files from SCCS.

       SCONS_HOME
              The (optional) path to the SCons library directory, initialized from  the  external
              environment.  If set, this is used to construct a shorter and more efficient search
              path in the $MSVSSCONS command line executed from Microsoft Visual  Studio  project
              files.

       SHCC   The C compiler used for generating shared-library objects.

       SHCCCOM
              The  command  line used to compile a C source file to a shared-library object file.
              Any options specified in  the  $SHCFLAGS,  $SHCCFLAGS  and  $CPPFLAGS  construction
              variables are included on this command line.

       SHCCCOMSTR
              The  string displayed when a C source file is compiled to a shared object file.  If
              this is not set, then $SHCCCOM (the command line) is displayed.

              env = Environment(SHCCCOMSTR = "Compiling shared object $TARGET")

       SHCCFLAGS
              Options that are passed to the C  and  C++  compilers  to  generate  shared-library
              objects.

       SHCFLAGS
              Options  that  are  passed  to  the  C compiler (only; not C++) to generate shared-
              library objects.

       SHCXX  The C++ compiler used for generating shared-library objects.

       SHCXXCOM
              The command line used to compile a C++ source file to a shared-library object file.
              Any  options  specified in the $SHCXXFLAGS and $CPPFLAGS construction variables are
              included on this command line.

       SHCXXCOMSTR
              The string displayed when a C++ source file is compiled to a  shared  object  file.
              If this is not set, then $SHCXXCOM (the command line) is displayed.

              env = Environment(SHCXXCOMSTR = "Compiling shared object $TARGET")

       SHCXXFLAGS
              Options that are passed to the C++ compiler to generate shared-library objects.

       SHELL  A  string naming the shell program that will be passed to the $SPAWN function.  See
              the $SPAWN construction variable for more information.

       SHF77  The Fortran 77 compiler used for generating  shared-library  objects.   You  should
              normally  set the $SHFORTRAN variable, which specifies the default Fortran compiler
              for all Fortran versions.  You only need to  set  $SHF77  if  you  need  to  use  a
              specific compiler or compiler version for Fortran 77 files.

       SHF77COM
              The  command  line  used  to  compile  a Fortran 77 source file to a shared-library
              object file.  You only need to set $SHF77COM if you need to use a specific  command
              line  for  Fortran  77  files.  You should normally set the $SHFORTRANCOM variable,
              which specifies the default command line for all Fortran versions.

       SHF77COMSTR
              The string displayed when a Fortran 77 source file is compiled to a  shared-library
              object  file.   If  this  is  not set, then $SHF77COM or $SHFORTRANCOM (the command
              line) is displayed.

       SHF77FLAGS
              Options that are passed to the Fortran  77  compiler  to  generated  shared-library
              objects.   You  only  need  to  set $SHF77FLAGS if you need to define specific user
              options for  Fortran  77  files.   You  should  normally  set  the  $SHFORTRANFLAGS
              variable,  which specifies the user-specified options passed to the default Fortran
              compiler for all Fortran versions.

       SHF77PPCOM
              The command line used to compile a Fortran  77  source  file  to  a  shared-library
              object  file  after first running the file through the C preprocessor.  Any options
              specified in the $SHF77FLAGS and $CPPFLAGS construction variables are  included  on
              this  command line.  You only need to set $SHF77PPCOM if you need to use a specific
              C-preprocessor command line for Fortran 77 files.   You  should  normally  set  the
              $SHFORTRANPPCOM  variable,  which specifies the default C-preprocessor command line
              for all Fortran versions.

       SHF77PPCOMSTR
              The string displayed when a Fortran 77 source file is compiled to a  shared-library
              object  file  after  first running the file through the C preprocessor.  If this is
              not set, then $SHF77PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

       SHF90  The Fortran 90 compiler used for generating  shared-library  objects.   You  should
              normally  set the $SHFORTRAN variable, which specifies the default Fortran compiler
              for all Fortran versions.  You only need to  set  $SHF90  if  you  need  to  use  a
              specific compiler or compiler version for Fortran 90 files.

       SHF90COM
              The  command  line  used  to  compile  a Fortran 90 source file to a shared-library
              object file.  You only need to set $SHF90COM if you need to use a specific  command
              line  for  Fortran  90  files.  You should normally set the $SHFORTRANCOM variable,
              which specifies the default command line for all Fortran versions.

       SHF90COMSTR
              The string displayed when a Fortran 90 source file is compiled to a  shared-library
              object  file.   If  this  is  not set, then $SHF90COM or $SHFORTRANCOM (the command
              line) is displayed.

       SHF90FLAGS
              Options that are passed to the Fortran  90  compiler  to  generated  shared-library
              objects.   You  only  need  to  set $SHF90FLAGS if you need to define specific user
              options for  Fortran  90  files.   You  should  normally  set  the  $SHFORTRANFLAGS
              variable,  which specifies the user-specified options passed to the default Fortran
              compiler for all Fortran versions.

       SHF90PPCOM
              The command line used to compile a Fortran  90  source  file  to  a  shared-library
              object  file  after first running the file through the C preprocessor.  Any options
              specified in the $SHF90FLAGS and $CPPFLAGS construction variables are  included  on
              this  command line.  You only need to set $SHF90PPCOM if you need to use a specific
              C-preprocessor command line for Fortran 90 files.   You  should  normally  set  the
              $SHFORTRANPPCOM  variable,  which specifies the default C-preprocessor command line
              for all Fortran versions.

       SHF90PPCOMSTR
              The string displayed when a Fortran 90 source file is compiled to a  shared-library
              object  file  after  first running the file through the C preprocessor.  If this is
              not set, then $SHF90PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

       SHF95  The Fortran 95 compiler used for generating  shared-library  objects.   You  should
              normally  set the $SHFORTRAN variable, which specifies the default Fortran compiler
              for all Fortran versions.  You only need to  set  $SHF95  if  you  need  to  use  a
              specific compiler or compiler version for Fortran 95 files.

       SHF95COM
              The  command  line  used  to  compile  a Fortran 95 source file to a shared-library
              object file.  You only need to set $SHF95COM if you need to use a specific  command
              line  for  Fortran  95  files.  You should normally set the $SHFORTRANCOM variable,
              which specifies the default command line for all Fortran versions.

       SHF95COMSTR
              The string displayed when a Fortran 95 source file is compiled to a  shared-library
              object  file.   If  this  is  not set, then $SHF95COM or $SHFORTRANCOM (the command
              line) is displayed.

       SHF95FLAGS
              Options that are passed to the Fortran  95  compiler  to  generated  shared-library
              objects.   You  only  need  to  set $SHF95FLAGS if you need to define specific user
              options for  Fortran  95  files.   You  should  normally  set  the  $SHFORTRANFLAGS
              variable,  which specifies the user-specified options passed to the default Fortran
              compiler for all Fortran versions.

       SHF95PPCOM
              The command line used to compile a Fortran  95  source  file  to  a  shared-library
              object  file  after first running the file through the C preprocessor.  Any options
              specified in the $SHF95FLAGS and $CPPFLAGS construction variables are  included  on
              this  command line.  You only need to set $SHF95PPCOM if you need to use a specific
              C-preprocessor command line for Fortran 95 files.   You  should  normally  set  the
              $SHFORTRANPPCOM  variable,  which specifies the default C-preprocessor command line
              for all Fortran versions.

       SHF95PPCOMSTR
              The string displayed when a Fortran 95 source file is compiled to a  shared-library
              object  file  after  first running the file through the C preprocessor.  If this is
              not set, then $SHF95PPCOM or $SHFORTRANPPCOM (the command line) is displayed.

       SHFORTRAN
              The default Fortran compiler used for generating shared-library objects.

       SHFORTRANCOM
              The command line used to compile a Fortran source file to a  shared-library  object
              file.

       SHFORTRANCOMSTR
              The  string  displayed  when  a Fortran source file is compiled to a shared-library
              object file.  If this  is  not  set,  then  $SHFORTRANCOM  (the  command  line)  is
              displayed.

       SHFORTRANFLAGS
              Options that are passed to the Fortran compiler to generate shared-library objects.

       SHFORTRANPPCOM
              The  command  line used to compile a Fortran source file to a shared-library object
              file after first  running  the  file  through  the  C  preprocessor.   Any  options
              specified  in the $SHFORTRANFLAGS and $CPPFLAGS construction variables are included
              on this command line.

       SHFORTRANPPCOMSTR
              The string displayed when a Fortran source file is  compiled  to  a  shared-library
              object  file  after  first running the file through the C preprocessor.  If this is
              not set, then $SHFORTRANPPCOM (the command line) is displayed.

       SHLIBEMITTER
              TODO

       SHLIBPREFIX
              The prefix used for shared library file names.

       SHLIBSUFFIX
              The suffix used for shared library file names.

       SHLINK The linker for programs that use shared libraries.

       SHLINKCOM
              The command line used to link programs using shared libraries.

       SHLINKCOMSTR
              The string displayed when programs using shared libraries are linked.  If  this  is
              not set, then $SHLINKCOM (the command line) is displayed.

              env = Environment(SHLINKCOMSTR = "Linking shared $TARGET")

       SHLINKFLAGS
              General  user  options  passed  to  the linker for programs using shared libraries.
              Note that this variable should not contain -l (or similar) options for linking with
              the libraries listed in $LIBS, nor -L (or similar) include search path options that
              scons generates  automatically  from  $LIBPATH.   See  $_LIBFLAGS  above,  for  the
              variable  that  expands  to  library-link options, and $_LIBDIRFLAGS above, for the
              variable that expands to library search path options.

       SHOBJPREFIX
              The prefix used for shared object file names.

       SHOBJSUFFIX
              The suffix used for shared object file names.

       SOURCE A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       SOURCE_URL
              The  URL  (web address) of the location from which the project was retrieved.  This
              is used to fill in the Source: field in the controlling information  for  Ipkg  and
              RPM packages.

       SOURCES
              A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       SPAWN  A command interpreter function that will be called to execute command line strings.
              The function must expect the following arguments:

              def spawn(shell, escape, cmd, args, env):

              sh  is  a string naming the shell program to use.  escape is a function that can be
              called to escape shell special characters in the command line.  cmd is the path  to
              the  command  to  be  executed.   args  is  the arguments to the command.  env is a
              dictionary of the environment variables in which the command should be executed.

       SUBST_DICT
              The dictionary used by the Substfile()  or  Textfile()  builders  for  substitution
              values.  It can be anything acceptable to the dict() constructor, so in addition to
              a dictionary, lists of tuples are also acceptable.

       SUBSTFILEPREFIX
              The prefix used for Substfile() file names, the null string by default.

       SUBSTFILESUFFIX
              The suffix used for Substfile() file names, the null string by default.

       SUMMARY
              A short summary of what the project is about.  This is used to fill in the Summary:
              field  in  the  controlling  information  for  Ipkg  and  RPM  packages, and as the
              Description: field in MSI packages.

       SWIG   The scripting language wrapper and interface generator.

       SWIGCFILESUFFIX
              The suffix that will be used for intermediate  C  source  files  generated  by  the
              scripting   language  wrapper  and  interface  generator.   The  default  value  is
              _wrap$CFILESUFFIX.  By default, this value is used whenever the -c++ option is  not
              specified as part of the $SWIGFLAGS construction variable.

       SWIGCOM
              The  command  line  used  to  call  the  scripting  language  wrapper and interface
              generator.

       SWIGCOMSTR
              The string displayed when calling the  scripting  language  wrapper  and  interface
              generator.  If this is not set, then $SWIGCOM (the command line) is displayed.

       SWIGCXXFILESUFFIX
              The  suffix  that  will  be used for intermediate C++ source files generated by the
              scripting  language  wrapper  and  interface  generator.   The  default  value   is
              _wrap$CFILESUFFIX.   By  default,  this  value  is used whenever the -c++ option is
              specified as part of the $SWIGFLAGS construction variable.

       SWIGDIRECTORSUFFIX
              The suffix that will be used for intermediate C++ header  files  generated  by  the
              scripting  language  wrapper and interface generator.  These are only generated for
              C++ code when the SWIG 'directors' feature is turned  on.   The  default  value  is
              _wrap.h.

       SWIGFLAGS
              General  options  passed to the scripting language wrapper and interface generator.
              This is where you should set -python, -perl5, -tcl, or whatever other  options  you
              want  to specify to SWIG.  If you set the -c++ option in this variable, scons will,
              by default, generate a C++ intermediate source file  with  the  extension  that  is
              specified as the $CXXFILESUFFIX variable.

       _SWIGINCFLAGS
              An  automatically-generated  construction variable containing the SWIG command-line
              options for specifying directories to be searched for included files.  The value of
              $_SWIGINCFLAGS  is  created  by  appending $SWIGINCPREFIX and $SWIGINCSUFFIX to the
              beginning and end of each directory in $SWIGPATH.

       SWIGINCPREFIX
              The prefix used to specify an include directory on the  SWIG  command  line.   This
              will  be  appended to the beginning of each directory in the $SWIGPATH construction
              variable when the $_SWIGINCFLAGS variable is automatically generated.

       SWIGINCSUFFIX
              The suffix used to specify an include directory on the  SWIG  command  line.   This
              will  be  appended  to  the  end  of  each  directory in the $SWIGPATH construction
              variable when the $_SWIGINCFLAGS variable is automatically generated.

       SWIGOUTDIR
              Specifies the  output  directory  in  which  the  scripting  language  wrapper  and
              interface  generator  should place generated language-specific files.  This will be
              used by SCons to identify the files that will be generated by the &swig; call,  and
              translated into the swig -outdir option on the command line.

       SWIGPATH
              The  list of directories that the scripting language wrapper and interface generate
              will search for included files.  The SWIG implicit dependency scanner  will  search
              these directories for include files.  The default is to use the same path specified
              as $CPPPATH.

              Don't explicitly put include directory arguments in SWIGFLAGS; the result  will  be
              non-portable  and  the  directories will not be searched by the dependency scanner.
              Note: directory names in SWIGPATH will be  looked-up  relative  to  the  SConscript
              directory  when  they are used in a command.  To force scons to look-up a directory
              relative to the root of the source tree use #:

              env = Environment(SWIGPATH='#/include')

              The directory look-up can also be forced using the Dir() function:

              include = Dir('include')
              env = Environment(SWIGPATH=include)

              The directory list will be  added  to  command  lines  through  the  automatically-
              generated  $_SWIGINCFLAGS  construction variable, which is constructed by appending
              the values of the $SWIGINCPREFIXand$SWIGINCSUFFIX  construction  variables  to  the
              beginning  and  end  of  each directory in $SWIGPATH.  Any command lines you define
              that need the SWIGPATH directory list should include $_SWIGINCFLAGS:

              env = Environment(SWIGCOM="my_swig -o $TARGET $_SWIGINCFLAGS $SORUCES")

       SWIGVERSION
              The version number of the SWIG tool.

       TAR    The tar archiver.

       TARCOM The command line used to call the tar archiver.

       TARCOMSTR
              The string displayed when archiving files using the tar archiver.  If this  is  not
              set, then $TARCOM (the command line) is displayed.

              env = Environment(TARCOMSTR = "Archiving $TARGET")

       TARFLAGS
              General options passed to the tar archiver.

       TARGET A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       TARGET_ARCH
              Sets the target architecture for Visual Studio  compiler  (i.e.  the  arch  of  the
              binaries generated by the compiler). If not set, default to $HOST_ARCH, or, if that
              is unset, to the architecture of the running machine's OS  (note  that  the  python
              build  or architecture has no effect).  This variable must be passed as an argument
              to the Environment()  constructor;  setting  it  later  has  no  effect.   This  is
              currently  only used on Windows, but in the future it will be used on other OSes as
              well.

              Valid values for Windows are x86, i386 (for 32 bits); amd64, emt64, x86_64 (for  64
              bits);  and  ia64  (Itanium).  For example, if you want to compile 64-bit binaries,
              you would set TARGET_ARCH='x86_64' in your SCons environment.

       TARGET_OS
                      The name of the target operating system for the compiled objects
                      created by this Environment.
                      This defaults to the value of HOST_OS, and the user can override it.
                      Currently only set for Win32.

       TARGETS
              A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       TARSUFFIX
              The suffix used for tar file names.

       TEMPFILEPREFIX
              The  prefix  for a temporary file used to execute lines longer than $MAXLINELENGTH.
              The default is '@'.  This may be set for toolchains that use other values, such  as
              '-@' for the diab compiler or '-via' for ARM toolchain.

       TEX    The TeX formatter and typesetter.

       TEXCOM The command line used to call the TeX formatter and typesetter.

       TEXCOMSTR
              The string displayed when calling the TeX formatter and typesetter.  If this is not
              set, then $TEXCOM (the command line) is displayed.

              env = Environment(TEXCOMSTR = "Building $TARGET from TeX input $SOURCES")

       TEXFLAGS
              General options passed to the TeX formatter and typesetter.

       TEXINPUTS
              List of directories that the LaTeX program will  search  for  include  directories.
              The  LaTeX  implicit  dependency scanner will search these directories for \include
              and \import files.

       TEXTFILEPREFIX
              The prefix used for Textfile() file names, the null string by default.

       TEXTFILESUFFIX
              The suffix used for Textfile() file names; .txt by default.

       TOOLS  A list of the names of the Tool specifications that are part of  this  construction
              environment.

       UNCHANGED_SOURCES
              A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       UNCHANGED_TARGETS
              A reserved variable name that may not be set or used in a construction environment.
              (See "Variable Substitution," below.)

       VENDOR The  person or organization who supply the packaged software.  This is used to fill
              in the Vendor: field in the controlling  information  for  RPM  packages,  and  the
              Manufacturer: field in the controlling information for MSI packages.

       VERSION
              The version of the project, specified as a string.

       WIN32_INSERT_DEF
              A deprecated synonym for $WINDOWS_INSERT_DEF.

       WIN32DEFPREFIX
              A deprecated synonym for $WINDOWSDEFPREFIX.

       WIN32DEFSUFFIX
              A deprecated synonym for $WINDOWSDEFSUFFIX.

       WIN32EXPPREFIX
              A deprecated synonym for $WINDOWSEXPSUFFIX.

       WIN32EXPSUFFIX
              A deprecated synonym for $WINDOWSEXPSUFFIX.

       WINDOWS_EMBED_MANIFEST
              Set  this  variable to True or 1 to embed the compiler-generated manifest (normally
              ${TARGET}.manifest) into all Windows exes and DLLs built with this environment,  as
              a  resource  during  their  link  step.   This  is done using $MT and $MTEXECOM and
              $MTSHLIBCOM.

       WINDOWS_INSERT_DEF
              When this is set to true, a library build of a Windows  shared  library  (.dllfile)
              will  also  build a corresponding .def file at the same time, if a .def file is not
              already listed as a build target.  The default is 0 (do not build a .def file).

       WINDOWS_INSERT_MANIFEST
              When this is set to true, scons will be aware of the .manifest files  generated  by
              Microsoft Visua C/C++ 8.

       WINDOWSDEFPREFIX
              The prefix used for Windows .def file names.

       WINDOWSDEFSUFFIX
              The suffix used for Windows .def file names.

       WINDOWSEXPPREFIX
              The prefix used for Windows .exp file names.

       WINDOWSEXPSUFFIX
              The suffix used for Windows .exp file names.

       WINDOWSPROGMANIFESTPREFIX
              The  prefix  used  for  executable  program  .manifest files generated by Microsoft
              Visual C/C++.

       WINDOWSPROGMANIFESTSUFFIX
              The suffix used for executable  program  .manifest  files  generated  by  Microsoft
              Visual C/C++.

       WINDOWSSHLIBMANIFESTPREFIX
              The  prefix  used  for shared library .manifest files generated by Microsoft Visual
              C/C++.

       WINDOWSSHLIBMANIFESTSUFFIX
              The suffix used for shared library .manifest files generated  by  Microsoft  Visual
              C/C++.

       X_IPK_DEPENDS
              This  is used to fill in the Depends: field in the controlling information for Ipkg
              packages.

       X_IPK_DESCRIPTION
              This is used to fill in the Description: field in the controlling  information  for
              Ipkg packages.  The default value is $SUMMARY0DESCRIPTION

       X_IPK_MAINTAINER
              This  is  used  to fill in the Maintainer: field in the controlling information for
              Ipkg packages.

       X_IPK_PRIORITY
              This is used to fill in the Priority: field in the controlling information for Ipkg
              packages.

       X_IPK_SECTION
              This  is used to fill in the Section: field in the controlling information for Ipkg
              packages.

       X_MSI_LANGUAGE
              This is used to fill in the Language: attribute in the controlling information  for
              MSI packages.

       X_MSI_LICENSE_TEXT
              The text of the software license in RTF format.  Carriage return characters will be
              replaced with the RTF equivalent \\par.

       X_MSI_UPGRADE_CODE
              TODO

       X_RPM_AUTOREQPROV
              This is used to fill in the AutoReqProv: field in the RPM .spec file.

       X_RPM_BUILD
              internal, but overridable

       X_RPM_BUILDREQUIRES
              This is used to fill in the BuildRequires: field in the RPM .spec file.

       X_RPM_BUILDROOT
              internal, but overridable

       X_RPM_CLEAN
              internal, but overridable

       X_RPM_CONFLICTS
              This is used to fill in the Conflicts: field in the RPM .spec file.

       X_RPM_DEFATTR
              This value is used as the default attributes for the files in the RPM package.  The
              default value is (-,root,root).

       X_RPM_DISTRIBUTION
              This is used to fill in the Distribution: field in the RPM .spec file.

       X_RPM_EPOCH
              This  is  used  to  fill in the Epoch: field in the controlling information for RPM
              packages.

       X_RPM_EXCLUDEARCH
              This is used to fill in the ExcludeArch: field in the RPM .spec file.

       X_RPM_EXLUSIVEARCH
              This is used to fill in the ExclusiveArch: field in the RPM .spec file.

       X_RPM_GROUP
              This is used to fill in the Group: field in the RPM .spec file.

       X_RPM_GROUP_lang
              This is used to fill in the Group(lang): field in the RPM .spec  file.   Note  that
              lang is not literal and should be replaced by the appropriate language code.

       X_RPM_ICON
              This is used to fill in the Icon: field in the RPM .spec file.

       X_RPM_INSTALL
              internal, but overridable

       X_RPM_PACKAGER
              This is used to fill in the Packager: field in the RPM .spec file.

       X_RPM_POSTINSTALL
              This is used to fill in the %post: section in the RPM .spec file.

       X_RPM_POSTUNINSTALL
              This is used to fill in the %postun: section in the RPM .spec file.

       X_RPM_PREFIX
              This is used to fill in the Prefix: field in the RPM .spec file.

       X_RPM_PREINSTALL
              This is used to fill in the %pre: section in the RPM .spec file.

       X_RPM_PREP
              internal, but overridable

       X_RPM_PREUNINSTALL
              This is used to fill in the %preun: section in the RPM .spec file.

       X_RPM_PROVIDES
              This is used to fill in the Provides: field in the RPM .spec file.

       X_RPM_REQUIRES
              This is used to fill in the Requires: field in the RPM .spec file.

       X_RPM_SERIAL
              This is used to fill in the Serial: field in the RPM .spec file.

       X_RPM_URL
              This is used to fill in the Url: field in the RPM .spec file.

       YACC   The parser generator.

       YACCCOM
              The command line used to call the parser generator to generate a source file.

       YACCCOMSTR
              The  string displayed when generating a source file using the parser generator.  If
              this is not set, then $YACCCOM (the command line) is displayed.

              env = Environment(YACCCOMSTR = "Yacc'ing $TARGET from $SOURCES")

       YACCFLAGS
              General options passed to the  parser  generator.   If  $YACCFLAGS  contains  a  -d
              option,  SCons assumes that the call will also create a .h file (if the yacc source
              file ends in a .y suffix) or a .hpp file (if the yacc source file  ends  in  a  .yy
              suffix)

       YACCHFILESUFFIX
              The  suffix  of  the  C  header  file generated by the parser generator when the -d
              option is used.  Note  that  setting  this  variable  does  not  cause  the  parser
              generator  to  generate a header file with the specified suffix, it exists to allow
              you to specify what suffix the parser generator will use of its  own  accord.   The
              default value is .h.

       YACCHXXFILESUFFIX
              The  suffix  of  the  C++ header file generated by the parser generator when the -d
              option is used.  Note  that  setting  this  variable  does  not  cause  the  parser
              generator  to  generate a header file with the specified suffix, it exists to allow
              you to specify what suffix the parser generator will use of its  own  accord.   The
              default value is .hpp, except on Mac OS X, where the default is ${TARGET.suffix}.h.
              because the default &bison; parser generator just appends .h to  the  name  of  the
              generated C++ file.

       YACCVCGFILESUFFIX
              The  suffix  of  the  file containing the VCG grammar automaton definition when the
              --graph= option is used.  Note that setting this variable does not cause the parser
              generator  to generate a VCG file with the specified suffix, it exists to allow you
              to specify what suffix the parser generator  will  use  of  its  own  accord.   The
              default value is .vcg.

       ZIP    The zip compression and file packaging utility.

       ZIPCOM The command line used to call the zip utility, or the internal Python function used
              to create a zip archive.

       ZIPCOMPRESSION
              The compression flag from the Python zipfile module used  by  the  internal  Python
              function  to  control  whether  the  zip archive is compressed or not.  The default
              value is zipfile.ZIP_DEFLATED, which creates a compressed zip archive.  This  value
              has no effect if the zipfile module is unavailable.

       ZIPCOMSTR
              The  string  displayed  when archiving files using the zip utility.  If this is not
              set, then $ZIPCOM (the command line or internal Python function) is displayed.

              env = Environment(ZIPCOMSTR = "Zipping $TARGET")

       ZIPFLAGS
              General options passed to the zip utility.

       ZIPSUFFIX
              The suffix used for zip file names.

       Construction variables can be retrieved  and  set  using  the  Dictionary  method  of  the
       construction environment:

              dict = env.Dictionary()
              dict["CC"] = "cc"

       or using the [] operator:

              env["CC"] = "cc"

       Construction variables can also be passed to the construction environment constructor:

              env = Environment(CC="cc")

       or when copying a construction environment using the Clone method:

              env2 = env.Clone(CC="cl.exe")

   Configure Contexts
       scons supports configure contexts, an integrated mechanism similar to the various AC_CHECK
       macros in GNU autoconf for testing for the existence of C header  files,  libraries,  etc.
       In  contrast  to autoconf, scons does not maintain an explicit cache of the tested values,
       but uses its normal dependency tracking to keep the checked values up  to  date.  However,
       users may override this behaviour with the --config command line option.

       The following methods can be used to perform checks:

       Configure(env, [custom_tests, conf_dir, log_file, config_h, clean, help])

       env.Configure([custom_tests, conf_dir, log_file, config_h, clean, help])
              This  creates  a  configure  context,  which  can  be  used to perform checks.  env
              specifies the environment for building the tests.  This environment may be modified
              when performing checks.  custom_tests is a dictionary containing custom tests.  See
              also the section about custom tests below.  By default, no custom tests  are  added
              to  the configure context.  conf_dir specifies a directory where the test cases are
              built.  Note that this directory is not used  for  building  normal  targets.   The
              default  value  is  the  directory  #/.sconf_temp.  log_file specifies a file which
              collects the output from commands that are executed to check for the  existence  of
              header  files,  libraries,  etc.  The default is the file #/config.log.  If you are
              using the VariantDir() method, you may want to specify a  subdirectory  under  your
              variant  directory.   config_h specifies a C header file where the results of tests
              will be written, e.g. #define HAVE_STDIO_H, #define HAVE_LIBM, etc.  The default is
              to  not  write a config.h file.  You can specify the same config.h file in multiple
              calls to Configure, in which  case  scons  will  concatenate  all  results  in  the
              specified  file.   Note that SCons uses its normal dependency checking to decide if
              it's necessary to rebuild the specified config_h file.  This means that the file is
              not  necessarily  re-built  each  time  scons  is  run,  but is only rebuilt if its
              contents will have changed and some target that depends on  the  config_h  file  is
              being built.

              The  optional  clean  and  help  arguments can be used to suppress execution of the
              configuration  tests  when  the  -c/--clean  or  -H/-h/--help  options  are   used,
              respectively.   The  default behavior is always to execute configure context tests,
              since the results of the tests may affect the list of targets to be cleaned or  the
              help  text.   If  the  configure  tests  do  not affect these, then you may add the
              clean=False or help=False arguments (or both) to avoid unnecessary test execution.

       A created Configure instance has the following associated methods:

       SConf.Finish(context)

       sconf.Finish()
              This method  should  be  called  after  configuration  is  done.   It  returns  the
              environment  as  modified by the configuration checks performed.  After this method
              is called, no further checks can be  performed  with  this  configuration  context.
              However, you can create a new Configure context to perform additional checks.  Only
              one context should be active at a time.

              The following Checks are predefined.  (This list will likely grow  larger  as  time
              goes by and developers contribute new useful tests.)

       SConf.CheckHeader(context, header, [include_quotes, language])

       sconf.CheckHeader(header, [include_quotes, language])
              Checks  if  header  is  usable in the specified language.  header may be a list, in
              which case the last item in the list is the header file  to  be  checked,  and  the
              previous list items are header files whose #include lines should precede the header
              line being checked for.   The  optional  argument  include_quotes  must  be  a  two
              character  string,  where  the  first  character  denotes the opening quote and the
              second character denotes the closing quote.  By default,  both  characters   are  "
              (double  quote).   The  optional  argument  language  should be either C or C++ and
              selects the compiler to be used for the check.  Returns  1  on  success  and  0  on
              failure.

       SConf.CheckCHeader(context, header, [include_quotes])

       sconf.CheckCHeader(header, [include_quotes])
              This  is a wrapper around SConf.CheckHeader which checks if header is usable in the
              C language.  header may be a list, in which case the last item in the list  is  the
              header  file  to  be  checked,  and  the previous list items are header files whose
              #include lines should precede the header line  being  checked  for.   The  optional
              argument  include_quotes  must be a two character string, where the first character
              denotes the opening quote and the second character denotes the closing quote  (both
              default to ").  Returns 1 on success and 0 on failure.

       SConf.CheckCXXHeader(context, header, [include_quotes])

       sconf.CheckCXXHeader(header, [include_quotes])
              This  is a wrapper around SConf.CheckHeader which checks if header is usable in the
              C++ language.  header may be a list, in which case the last item in the list is the
              header  file  to  be  checked,  and  the previous list items are header files whose
              #include lines should precede the header line  being  checked  for.   The  optional
              argument  include_quotes  must be a two character string, where the first character
              denotes the opening quote and the second character denotes the closing quote  (both
              default to ").  Returns 1 on success and 0 on failure.

       SConf.CheckFunc(context,, function_name, [header, language])

       sconf.CheckFunc(function_name, [header, language])
              Checks  if the specified C or C++ function is available.  function_name is the name
              of the function to check for.  The optional header argument is a string  that  will
              be  placed  at  the  top  of  the  test  file that will be compiled to check if the
              function exists; the default is:
              #ifdef __cplusplus
              extern "C"
              #endif
              char function_name();
       The optional language argument should be C or C++ and selects the compiler to be used  for
       the check; the default is "C".

       SConf.CheckLib(context, [library, symbol, header, language, autoadd=1])

       sconf.CheckLib([library, symbol, header, language, autoadd=1])
              Checks  if  library  provides symbol.  If the value of autoadd is 1 and the library
              provides the specified  symbol,  appends  the  library  to  the  LIBS  construction
              environment variable.  library may also be None (the default), in which case symbol
              is checked with the current LIBS variable, or a list of  library  names,  in  which
              case  each library in the list will be checked for symbol.  If symbol is not set or
              is None, then SConf.CheckLib() just checks if you can link  against  the  specified
              library.   The  optional  language  argument  should  be  C  or C++ and selects the
              compiler to be used for the check; the default  is  "C".   The  default  value  for
              autoadd is 1.  This method returns 1 on success and 0 on error.

       SConf.CheckLibWithHeader(context, library, header, language, [call, autoadd])

       sconf.CheckLibWithHeader(library, header, language, [call, autoadd])

              In contrast to the SConf.CheckLib call, this call provides a more sophisticated way
              to check against libraries.  Again, library specifies the  library  or  a  list  of
              libraries to check.  header specifies a header to check for.  header may be a list,
              in which case the last item in the list is the header file to be checked,  and  the
              previous list items are header files whose #include lines should precede the header
              line being checked for.  language  may  be  one  of  'C','c','CXX','cxx','C++'  and
              'c++'.   call  can  be  any valid expression (with a trailing ';').  If call is not
              set, the default simply checks that you can link  against  the  specified  library.
              autoadd  specifies whether to add the library to the environment (only if the check
              succeeds). This method returns 1 on success and 0 on error.

       SConf.CheckType(context, type_name, [includes, language])

       sconf.CheckType(type_name, [includes, language])
              Checks for the existence of a type defined by  typedef.   type_name  specifies  the
              typedef  name  to  check for.  includes is a string containing one or more #include
              lines that will be inserted into the program that will  be  run  to  test  for  the
              existence  of  the  type.   The  optional  language argument should be C or C++ and
              selects the compiler to be used for the check; the default is "C".  Example:
              sconf.CheckType('foo_type', '#include "my_types.h"', 'C++')

       Configure.CheckCC(self)
              Checks whether the C compiler (as defined by the CC construction variable) works by
              trying to compile a small source file.

              By  default, SCons only detects if there is a program with the correct name, not if
              it is a functioning compiler.

              This uses the exact same command than the one used by  the  object  builder  for  C
              source  file,  so  it  can be used to detect if a particular compiler flag works or
              not.

       Configure.CheckCXX(self)
              Checks whether the C++ compiler (as defined by the CXX construction variable) works
              by  trying  to compile a small source file. By default, SCons only detects if there
              is a program with the correct name, not if it is a functioning compiler.

              This uses the exact same command than the one used by the object  builder  for  CXX
              source  files,  so  it can be used to detect if a particular compiler flag works or
              not.

       Configure.CheckSHCC(self)
              Checks whether the C compiler (as defined by the SHCC construction variable)  works
              by  trying  to compile a small source file. By default, SCons only detects if there
              is a program with the correct name, not if it is a functioning compiler.

              This uses the exact same command than the one used by  the  object  builder  for  C
              source  file,  so  it  can be used to detect if a particular compiler flag works or
              not. This does not check whether the object code can be  used  to  build  a  shared
              library, only that the compilation (not link) succeeds.

       Configure.CheckSHCXX(self)
              Checks  whether  the  C++  compiler (as defined by the SHCXX construction variable)
              works by trying to compile a small source file. By default, SCons only  detects  if
              there is a program with the correct name, not if it is a functioning compiler.

              This  uses  the  exact same command than the one used by the object builder for CXX
              source files, so it can be used to detect if a particular compiler  flag  works  or
              not.  This  does  not  check  whether the object code can be used to build a shared
              library, only that the compilation (not link) succeeds.

       Example of a typical Configure usage:

              env = Environment()
              conf = Configure( env )
              if not conf.CheckCHeader( 'math.h' ):
                  print 'We really need math.h!'
                  Exit(1)
              if conf.CheckLibWithHeader( 'qt', 'qapp.h', 'c++',
                      'QApplication qapp(0,0);' ):
                  # do stuff for qt - usage, e.g.
                  conf.env.Append( CPPFLAGS = '-DWITH_QT' )
              env = conf.Finish()

       SConf.CheckTypeSize(context, type_name, [header, language, expect])

       sconf.CheckTypeSize(type_name, [header, language, expect])
              Checks for the size of a type defined by typedef.  type_name specifies the  typedef
              name to check for.  The optional header argument is a string that will be placed at
              the top of the test file that will be compiled to check if the function exists; the
              default  is  empty.   The optional language argument should be C or C++ and selects
              the compiler to be used for the check; the default is  "C".   The  optional  expect
              argument  should  be  an integer.  If this argument is used, the function will only
              check whether the type given in type_name has the expected size  (in  bytes).   For
              example,  CheckTypeSize('short',  expect  = 2) will return success only if short is
              two bytes.

       SConf.CheckDeclaration(context, symbol, [includes, language])

       sconf.CheckDeclaration(symbol, [includes, language])
              Checks if the specified symbol is declared.  includes is a string containing one or
              more #include lines that will be inserted into the program that will be run to test
              for the existence of the type.  The optional language argument should be C  or  C++
              and selects the compiler to be used for the check; the default is "C".

       SConf.Define(context, symbol, [value, comment])

       sconf.Define(symbol, [value, comment])
              This  function  does not check for anything, but defines a preprocessor symbol that
              will be added to the configuration header file.  It is the equivalent of AC_DEFINE,
              and  defines  the  symbol  name  with  the  optional value and the optional comment
              comment.

              Examples:

              env = Environment()
              conf = Configure( env )

              # Puts the following line in the config header file:
              #    #define A_SYMBOL
              conf.Define('A_SYMBOL')

              # Puts the following line in the config header file:
              #    #define A_SYMBOL 1
              conf.Define('A_SYMBOL', 1)

              Be careful about quoting string values, though:

              env = Environment()
              conf = Configure( env )

              # Puts the following line in the config header file:
              #    #define A_SYMBOL YA
              conf.Define('A_SYMBOL', "YA")

              # Puts the following line in the config header file:
              #    #define A_SYMBOL "YA"
              conf.Define('A_SYMBOL', '"YA"')

              For comment:

              env = Environment()
              conf = Configure( env )

              # Puts the following lines in the config header file:
              #    /* Set to 1 if you have a symbol */
              #    #define A_SYMBOL 1
              conf.Define('A_SYMBOL', 1, 'Set to 1 if you have a symbol')

       You can define your own custom checks.  in addition to the predefined checks.   These  are
       passed  in  a dictionary to the Configure function.  This dictionary maps the names of the
       checks to user defined Python  callables  (either  Python  functions  or  class  instances
       implementing  the  __call__  method).   The  first  argument  of  the  call  is  always  a
       CheckContext instance followed by the arguments, which must be supplied by the user of the
       check.  These CheckContext instances define the following methods:

       CheckContext.Message(self, text)

              Usually  called  before  the check is started.  text will be displayed to the user,
              e.g. 'Checking for library X...'

       CheckContext.Result(self,, res)

              Usually called after the check is done.  res can be either an integer or a  string.
              In  the  former case, 'yes' (res != 0) or 'no' (res == 0) is displayed to the user,
              in the latter case the given string is displayed.

       CheckContext.TryCompile(self, text, extension)
              Checks if a file with the specified extension (e.g. '.c') containing  text  can  be
              compiled  using  the  environment's  Object  builder. Returns 1 on success and 0 on
              failure.

       CheckContext.TryLink(self, text, extension)
              Checks, if a file with the specified extension (e.g. '.c') containing text  can  be
              compiled  using  the  environment's  Program builder. Returns 1 on success and 0 on
              failure.

       CheckContext.TryRun(self, text, extension)
              Checks, if a file with the specified extension (e.g. '.c') containing text  can  be
              compiled  using  the environment's Program builder. On success, the program is run.
              If the program executes successfully (that is, its return status is 0), a tuple (1,
              outputStr)  is returned, where outputStr is the standard output of the program.  If
              the program fails execution (its return  status  is  non-zero),  then  (0,  '')  is
              returned.

       CheckContext.TryAction(self, action, [text, extension])
              Checks  if  the  specified  action  with  an  optional source file (contents text ,
              extension extension = '' ) can be executed.  action may be anything  which  can  be
              converted  to  a  scons  Action.   On  success,  (1,  outputStr) is returned, where
              outputStr is the content of the target file.  On failure (0, '') is returned.

       CheckContext.TryBuild(self, builder, [text, extension])
              Low level implementation for testing specific builds; the methods above  are  based
              on  this  method.   Given  the  Builder instance builder and the optional text of a
              source file with optional extension, this method returns 1  on  success  and  0  on
              failure. In addition, self.lastTarget is set to the build target node, if the build
              was successful.

       Example for implementing and using custom tests:

              def CheckQt(context, qtdir):
                  context.Message( 'Checking for qt ...' )
                  lastLIBS = context.env['LIBS']
                  lastLIBPATH = context.env['LIBPATH']
                  lastCPPPATH= context.env['CPPPATH']
                  context.env.Append(LIBS = 'qt', LIBPATH = qtdir + '/lib', CPPPATH = qtdir + '/include' )
                  ret = context.TryLink("""
              #include <qapp.h>
              int main(int argc, char **argv) {
                QApplication qapp(argc, argv);
                return 0;
              }
              """)
                  if not ret:
                      context.env.Replace(LIBS = lastLIBS, LIBPATH=lastLIBPATH, CPPPATH=lastCPPPATH)
                  context.Result( ret )
                  return ret

              env = Environment()
              conf = Configure( env, custom_tests = { 'CheckQt' : CheckQt } )
              if not conf.CheckQt('/usr/lib/qt'):
                  print 'We really need qt!'
                  Exit(1)
              env = conf.Finish()

   Command-Line Construction Variables
       Often when building software, some  variables  must  be  specified  at  build  time.   For
       example, libraries needed for the build may be in non-standard locations, or site-specific
       compiler options may need to be passed to the compiler.  scons provides a Variables object
       to support overriding construction variables on the command line:
              $ scons VARIABLE=foo
       The  variable  values  can also be specified in a text-based SConscript file.  To create a
       Variables object, call the Variables() function:

       Variables([files], [args])
              This creates a Variables object that will read construction variables from the file
              or  list  of filenames specified in files.  If no files are specified, or the files
              argument is None, then no files will be read.  The  optional  argument  args  is  a
              dictionary  of values that will override anything read from the specified files; it
              is primarily intended to be passed the ARGUMENTS dictionary  that  holds  variables
              specified on the command line.  Example:

              vars = Variables('custom.py')
              vars = Variables('overrides.py', ARGUMENTS)
              vars = Variables(None, {FOO:'expansion', BAR:7})

       Variables objects have the following methods:

       Add(key, [help, default, validator, converter])
              This adds a customizable construction variable to the Variables object.  key is the
              name of the variable.  help is the help text for  the  variable.   default  is  the
              default  value  of  the  variable;  if  the  default  value is None and there is no
              explicit value specified, the construction  variable  will  not  be  added  to  the
              construction  environment.   validator  is  called  to  validate  the  value of the
              variable, and should take  three  arguments:  key,  value,  and  environment.   The
              recommended  way  to  handle an invalid value is to raise an exception (see example
              below).  converter is called  to  convert  the  value  before  putting  it  in  the
              environment,  and  should  take  either  a  value, or the value and environment, as
              parameters.  The converter must return a value, which  will  be  converted  into  a
              string  before  being  validated  by  the  validator (if any) and then added to the
              environment.

              Examples:

              vars.Add('CC', 'The C compiler')

              def validate_color(key, val, env):
                  if not val in ['red', 'blue', 'yellow']:
                      raise Exception("Invalid color value '%s'" % val)
              vars.Add('COLOR', validator=valid_color)

       AddVariables(list)
              A wrapper script that  adds  multiple  customizable  construction  variables  to  a
              Variables  object.   list  is  a  list  of  tuple  or list objects that contain the
              arguments for an individual call to the Add method.

              opt.AddVariables(
                     ('debug', '', 0),
                     ('CC', 'The C compiler'),
                     ('VALIDATE', 'An option for testing validation',
                      'notset', validator, None),
                  )

       Update(env, [args])
              This updates a  construction  environment  env  with  the  customized  construction
              variables.   Any  specified  variables  that  are  not configured for the Variables
              object will be saved and may  be  retrieved  with  the  UnknownVariables()  method,
              below.

              Normally  this  method  is not called directly, but is called indirectly by passing
              the Variables object to the Environment() function:

              env = Environment(variables=vars)

              The text file(s) that were specified when the  Variables  object  was  created  are
              executed  as Python scripts, and the values of (global) Python variables set in the
              file are added to the construction environment.

              Example:

              CC = 'my_cc'

       UnknownVariables()
              Returns a dictionary containing any variables that were  specified  either  in  the
              files  or  the  dictionary with which the Variables object was initialized, but for
              which the Variables object was not configured.

              env = Environment(variables=vars)
              for key, value in vars.UnknownVariables():
                  print "unknown variable:  %s=%s" % (key, value)

       Save(filename, env)
              This saves the currently set variables into a script file named filename  that  can
              be  used  on  the next invocation to automatically load the current settings.  This
              method combined with the Variables  method  can  be  used  to  support  caching  of
              variables between runs.

              env = Environment()
              vars = Variables(['variables.cache', 'custom.py'])
              vars.Add(...)
              vars.Update(env)
              vars.Save('variables.cache', env)

       GenerateHelpText(env, [sort])
              This  generates  help  text  documenting  the  customizable  construction variables
              suitable to passing in to the Help() function.  env is the construction environment
              that  will be used to get the actual values of customizable variables. Calling with
              an optional sort function will cause the output  to  be  sorted  by  the  specified
              argument.  The specific sort function should take two arguments and return -1, 0 or
              1 (like the standard Python cmp function).

              Help(vars.GenerateHelpText(env))
              Help(vars.GenerateHelpText(env, sort=cmp))

       FormatVariableHelpText(env, opt, help, default, actual)
              This method returns a formatted string containing the printable help text  for  one
              option.    It   is   normally   not   called   directly,   but  is  called  by  the
              GenerateHelpText() method to create the returned help text.  It may  be  overridden
              with  your  own  function  that  takes  the arguments specified above and returns a
              string of help text formatted to your liking.   Note  that  the  GenerateHelpText()
              will  not  put  any  blank lines or extra characters in between the entries, so you
              must add those characters to the returned string if you want the entries separated.

              def my_format(env, opt, help, default, actual):
                  fmt = "94s: default=%s actual=%s (%s)0
                  return fmt % (opt, default. actual, help)
              vars.FormatVariableHelpText = my_format

       To make it more convenient to work with customizable Variables, scons provides a number of
       functions that make it easy to set up various types of Variables:

       BoolVariable(key, help, default)
              Return  a  tuple  of arguments to set up a Boolean option.  The option will use the
              specified name key, have a default value of default, and display the specified help
              text.  The option will interpret the values y, yes, t, true, 1, on and all as true,
              and the values n, no, f, false, 0, off and none as false.

       EnumVariable(key, help, default, allowed_values, [map, ignorecase])
              Return a tuple of arguments to set up an  option  whose  value  may  be  one  of  a
              specified  list of legal enumerated values.  The option will use the specified name
              key, have a default value of default, and display the  specified  help  text.   The
              option will only support those values in the allowed_values list.  The optional map
              argument is a dictionary that can be used to convert  input  values  into  specific
              legal  values  in  the  allowed_values list.  If the value of ignore_case is 0 (the
              default), then the values are case-sensitive.  If the value of  ignore_case  is  1,
              then  values  will  be matched case-insensitive.  If the value of ignore_case is 1,
              then values will  be  matched  case-insensitive,  and  all  input  values  will  be
              converted to lower case.

       ListVariable(key, help, default, names, [,map])
              Return a tuple of arguments to set up an option whose value may be one or more of a
              specified list of legal enumerated values.  The option will use the specified  name
              key,  have  a  default  value of default, and display the specified help text.  The
              option will only support the values all, none, or the values  in  the  names  list.
              More  than  one  value  may be specified, with all values separated by commas.  The
              default may be a string of comma-separated default values, or a list of the default
              values.   The  optional  map  argument  is a dictionary that can be used to convert
              input values into specific legal values in the names list.

       PackageVariable(key, help, default)
              Return a tuple of arguments to set up an option whose value is a  path  name  of  a
              package  that  may be enabled, disabled or given an explicit path name.  The option
              will use the specified name key, have a default value of default, and  display  the
              specified  help  text.  The option will support the values yes, true, on, enable or
              search, in which case the specified default will be used, or the option may be  set
              to  an  arbitrary  string  (typically  the  path  name  to  a package that is being
              enabled).  The option will also support the values no, false,  off  or  disable  to
              disable use of the specified option.

       PathVariable(key, help, default, [validator])
              Return  a  tuple  of  arguments to set up an option whose value is expected to be a
              path name.  The option will use the specified name key, have  a  default  value  of
              default,  and  display  the  specified  help  text.  An additional validator may be
              specified that will be called to verify that  the  specified  path  is  acceptable.
              SCons  supplies  the  following ready-made validators: PathVariable.PathExists (the
              default), which verifies that the specified path  exists;  PathVariable.PathIsFile,
              which verifies that the specified path is an existing file; PathVariable.PathIsDir,
              which   verifies   that   the   specified   path   is   an   existing    directory;
              PathVariable.PathIsDirCreate, which verifies that the specified path is a directory
              and  will  create  the  specified  directory  if  the  path  does  not  exist;  and
              PathVariable.PathAccept,  which  simply  accepts  the  specific  path name argument
              without validation, and which is suitable if you want your  users  to  be  able  to
              specify  a  directory  path  that will be created as part of the build process, for
              example.  You may supply  your  own  validator  function,  which  must  take  three
              arguments  (key, the name of the variable to be set; val, the specified value being
              checked; and env, the construction environment) and should raise  an  exception  if
              the specified value is not acceptable.

       These  functions  make  it  convenient  to  create  a  number of variables with consistent
       behavior in a single call to the AddVariables method:

              vars.AddVariables(
                  BoolVariable('warnings', 'compilation with -Wall and similiar', 1),
                  EnumVariable('debug', 'debug output and symbols', 'no'
                             allowed_values=('yes', 'no', 'full'),
                             map={}, ignorecase=0),  # case sensitive
                  ListVariable('shared',
                             'libraries to build as shared libraries',
                             'all',
                             names = list_of_libs),
                  PackageVariable('x11',
                                'use X11 installed here (yes = search some places)',
                                'yes'),
                  PathVariable('qtdir', 'where the root of Qt is installed', qtdir),
                  PathVariable('foopath', 'where the foo library is installed', foopath,
                             PathVariable.PathIsDir),

              )

   File and Directory Nodes
       The File() and Dir() functions return File and Dir Nodes, respectively.   python  objects,
       respectively.   Those  objects  have  several user-visible attributes and methods that are
       often useful:

       path   The build path of the given file or directory.  This path is relative to  the  top-
              level  directory  (where the SConstruct file is found).  The build path is the same
              as the source path if variant_dir is not being used.

       abspath
              The absolute build path of the given file or directory.

       srcnode()
              The srcnode() method returns another File or Dir  object  representing  the  source
              path of the given File or Dir.  The

              # Get the current build dir's path, relative to top.
              Dir('.').path
              # Current dir's absolute path
              Dir('.').abspath
              # Next line is always '.', because it is the top dir's path relative to itself.
              Dir('#.').path
              File('foo.c').srcnode().path   # source path of the given source file.

              # Builders also return File objects:
              foo = env.Program('foo.c')
              print "foo will be built in %s"%foo.path

       A Dir Node or File Node can also be used to create file and subdirectory Nodes relative to
       the generating Node.  A Dir Node  will  place  the  new  Nodes  within  the  directory  it
       represents.   A  File  node will place the new Nodes within its parent directory (that is,
       "beside" the file in question).  If d is a Dir (directory) Node and f  is  a  File  (file)
       Node, then these methods are available:

       d.Dir(name)
              Returns a directory Node for a subdirectory of d named name.

       d.File(name)
              Returns a file Node for a file within d named name.

       d.Entry(name)
              Returns an unresolved Node within d named name.

       f.Dir(name)
              Returns a directory named name within the parent directory of f.

       f.File(name)
              Returns a file named name within the parent directory of f.

       f.Entry(name)
              Returns an unresolved Node named name within the parent directory of f.

       For example:

              # Get a Node for a file within a directory
              incl = Dir('include')
              f = incl.File('header.h')

              # Get a Node for a subdirectory within a directory
              dist = Dir('project-3.2.1)
              src = dist.Dir('src')

              # Get a Node for a file in the same directory
              cfile = File('sample.c')
              hfile = cfile.File('sample.h')

              # Combined example
              docs = Dir('docs')
              html = docs.Dir('html')
              index = html.File('index.html')
              css = index.File('app.css')

EXTENDING SCONS

   Builder Objects
       scons can be extended to build different types of targets by adding new Builder objects to
       a construction environment.  In general, you should only need to add a new Builder  object
       when  you  want to build a new type of file or other external target.  If you just want to
       invoke a different compiler or other tool to build a  Program,  Object,  Library,  or  any
       other type of output file for which scons already has an existing Builder, it is generally
       much easier to use those existing Builders in a construction  environment  that  sets  the
       appropriate construction variables (CC, LINK, etc.).

       Builder  objects are created using the Builder function.  The Builder function accepts the
       following arguments:

       action The command line string used to build the target from the source.  action can  also
              be:  a  list  of  strings representing the command to be executed and its arguments
              (suitable for enclosing white space in an argument), a  dictionary  mapping  source
              file  name  suffixes  to  any  combination  of command line strings (if the builder
              should accept multiple source file extensions), a Python function; an Action object
              (see the next section); or a list of any of the above.

              An action function takes three arguments: source - a list of source nodes, target -
              a list of target nodes, env - the construction environment.

       prefix The prefix that will be prepended to the target file name.  This may  be  specified
              as a:

                 * string,

                 *  callable  object  -  a function or other callable that takes two arguments (a
                       construction environment and a list of sources) and returns a prefix,

                 * dictionary - specifies a mapping from a specific source suffix (of  the  first
                       source  specified)  to  a  corresponding  target  prefix.  Both the source
                       suffix and target  prefix  specifications  may  use  environment  variable
                       substitution,   and   the  target  prefix  (the  'value'  entries  in  the
                       dictionary) may also be a callable object.  The default target prefix  may
                       be indicated by a dictionary entry with a key value of None.

              b = Builder("build_it < $SOURCE > $TARGET",
                          prefix = "file-")

              def gen_prefix(env, sources):
                  return "file-" + env['PLATFORM'] + '-'
              b = Builder("build_it < $SOURCE > $TARGET",
                          prefix = gen_prefix)

              b = Builder("build_it < $SOURCE > $TARGET",
                          suffix = { None: "file-",
                                     "$SRC_SFX_A": gen_prefix })

       suffix The suffix that will be appended to the target file name.  This may be specified in
              the same manner as the prefix above.  If the suffix is a string,  then  scons  will
              append  a '.' to the beginning of the suffix if it's not already there.  The string
              returned by callable object (or obtained from the dictionary) is untouched and must
              append its own '.'  to the beginning if one is desired.

              b = Builder("build_it < $SOURCE > $TARGET"
                          suffix = "-file")

              def gen_suffix(env, sources):
                  return "." + env['PLATFORM'] + "-file"
              b = Builder("build_it < $SOURCE > $TARGET",
                          suffix = gen_suffix)

              b = Builder("build_it < $SOURCE > $TARGET",
                          suffix = { None: ".sfx1",
                                     "$SRC_SFX_A": gen_suffix })

       ensure_suffix
              When  set to any true value, causes scons to add the target suffix specified by the
              suffix keyword to any target strings that have a different  suffix.   (The  default
              behavior  is to leave untouched any target file name that looks like it already has
              any suffix.)

              b1 = Builder("build_it < $SOURCE > $TARGET"
                           suffix = ".out")
              b2 = Builder("build_it < $SOURCE > $TARGET"
                           suffix = ".out",
                           ensure_suffix)
              env = Environment()
              env['BUILDERS']['B1'] = b1
              env['BUILDERS']['B2'] = b2

              # Builds "foo.txt" because ensure_suffix is not set.
              env.B1('foo.txt', 'foo.in')

              # Builds "bar.txt.out" because ensure_suffix is set.
              env.B2('bar.txt', 'bar.in')

       src_suffix
              The expected source file name suffix.  This may be a string or a list of strings.

       target_scanner
              A Scanner object that will be invoked to find implicit dependencies for this target
              file.   This keyword argument should be used for Scanner objects that find implicit
              dependencies based only on the target file and the  construction  environment,  not
              for  implicit  dependencies  based  on  source  files.   (See  the section "Scanner
              Objects" below, for information about creating Scanner objects.)

       source_scanner
              A Scanner object that will be invoked to find implicit dependencies in  any  source
              files used to build this target file.  This is where you would specify a scanner to
              find things like #include lines in source files.  The pre-built DirScanner  Scanner
              object  may  be  used to indicate that this Builder should scan directory trees for
              on-disk changes to files that scons does not  know  about  from  other  Builder  or
              function  calls.   (See  the section "Scanner Objects" below, for information about
              creating your own Scanner objects.)

       target_factory
              A factory function that the Builder will use  to  turn  any  targets  specified  as
              strings  into  SCons  Nodes.  By default, SCons assumes that all targets are files.
              Other useful target_factory values include  Dir,  for  when  a  Builder  creates  a
              directory  target,  and  Entry,  for  when  a  Builder  can create either a file or
              directory target.

              Example:

              MakeDirectoryBuilder = Builder(action=my_mkdir, target_factory=Dir)
              env = Environment()
              env.Append(BUILDERS = {'MakeDirectory':MakeDirectoryBuilder})
              env.MakeDirectory('new_directory', [])

              Note that the call to the MakeDirectory Builder needs to specify  an  empty  source
              list  to  make  the  string  represent the builder's target; without that, it would
              assume the argument is the source, and would try to deduce the target name from it,
              which  in  the  absence  of an automatically-added prefix or suffix would lead to a
              matching target and source name and a circular dependency.

       source_factory
              A factory function that the Builder will use  to  turn  any  sources  specified  as
              strings  into  SCons  Nodes.   By default, SCons assumes that all source are files.
              Other useful source_factory values include Dir, for when a Builder uses a directory
              as  a  source, and Entry, for when a Builder can use files or directories (or both)
              as sources.

              Example:

              CollectBuilder = Builder(action=my_mkdir, source_factory=Entry)
              env = Environment()
              env.Append(BUILDERS = {'Collect':CollectBuilder})
              env.Collect('archive', ['directory_name', 'file_name'])

       emitter
              A function or list of functions to manipulate the target and  source  lists  before
              dependencies  are  established  and  the target(s) are actually built.  emitter can
              also be a string containing  a  construction  variable  to  expand  to  an  emitter
              function  or  list  of  functions,  or a dictionary mapping source file suffixes to
              emitter functions.  (Only the suffix of the first source file is used to select the
              actual emitter function from an emitter dictionary.)

              An  emitter function takes three arguments: source - a list of source nodes, target
              - a list of target nodes, env - the  construction  environment.   An  emitter  must
              return  a  tuple  containing  two  lists,  the  list of targets to be built by this
              builder, and the list of sources for this builder.

              Example:

              def e(target, source, env):
                  return (target + ['foo.foo'], source + ['foo.src'])

              # Simple association of an emitter function with a Builder.
              b = Builder("my_build < $TARGET > $SOURCE",
                          emitter = e)

              def e2(target, source, env):
                  return (target + ['bar.foo'], source + ['bar.src'])

              # Simple association of a list of emitter functions with a Builder.
              b = Builder("my_build < $TARGET > $SOURCE",
                          emitter = [e, e2])

              # Calling an emitter function through a construction variable.
              env = Environment(MY_EMITTER = e)
              b = Builder("my_build < $TARGET > $SOURCE",
                          emitter = '$MY_EMITTER')

              # Calling a list of emitter functions through a construction variable.
              env = Environment(EMITTER_LIST = [e, e2])
              b = Builder("my_build < $TARGET > $SOURCE",
                          emitter = '$EMITTER_LIST')

              # Associating multiple emitters with different file
              # suffixes using a dictionary.
              def e_suf1(target, source, env):
                  return (target + ['another_target_file'], source)
              def e_suf2(target, source, env):
                  return (target, source + ['another_source_file'])
              b = Builder("my_build < $TARGET > $SOURCE",
                          emitter = {'.suf1' : e_suf1,
                                     '.suf2' : e_suf2})

       multi  Specifies whether this builder is allowed to be called multiple times for the  same
              target  file(s).  The  default  is  0,  which  means  the builder can not be called
              multiple times for the same target file(s). Calling a builder  multiple  times  for
              the  same  target  simply  adds  additional  source  files to the target; it is not
              allowed to change the environment associated  with  the  target,  specify  addition
              environment overrides, or associate a different builder with the target.

       env    A  construction  environment  that  can  be  used  to  fetch source code using this
              Builder.  (Note that this environment is not  used  for  normal  builds  of  normal
              target  files,  which use the environment that was used to call the Builder for the
              target file.)

       generator
              A function that returns a list of actions  that  will  be  executed  to  build  the
              target(s)  from  the source(s).  The returned action(s) may be an Action object, or
              anything that can be converted into an Action object (see the next section).

              The generator function takes four arguments: source  -  a  list  of  source  nodes,
              target  - a list of target nodes, env - the construction environment, for_signature
              - a Boolean value  that  specifies  whether  the  generator  is  being  called  for
              generating  a  build  signature  (as  opposed  to  actually executing the command).
              Example:

              def g(source, target, env, for_signature):
                  return [["gcc", "-c", "-o"] + target + source]

              b = Builder(generator=g)

              The generator and action arguments must not both be used for the same Builder.

       src_builder
              Specifies a builder to use when a source file name suffix does not match any of the
              suffixes of the builder. Using this argument produces a multi-stage builder.

       single_source
              Specifies  that  this builder expects exactly one source file per call. Giving more
              than one source file without  target  files  results  in  implicitely  calling  the
              builder  multiple  times (once for each source given). Giving multiple source files
              together with target files results in a UserError exception.

              The generator and action arguments must not both be used for the same Builder.

       source_ext_match
              When the specified action argument is a dictionary, the  default  behavior  when  a
              builder  is passed multiple source files is to make sure that the extensions of all
              the source files match.  If it is legal for this builder to be called with  a  list
              of  source files with different extensions, this check can be suppressed by setting
              source_ext_match to None or some other non-true value.   When  source_ext_match  is
              disable, scons will use the suffix of the first specified source file to select the
              appropriate action from the action dictionary.

              In the following example, the  setting  of  source_ext_match  prevents  scons  from
              exiting with an error due to the mismatched suffixes of foo.in and foo.extra.

              b = Builder(action={'.in' : 'build $SOURCES > $TARGET'},
                          source_ext_match = None)

              env = Environment(BUILDERS = {'MyBuild':b})
              env.MyBuild('foo.out', ['foo.in', 'foo.extra'])

       env    A  construction  environment  that  can  be  used  to  fetch source code using this
              Builder.  (Note that this environment is not  used  for  normal  builds  of  normal
              target  files,  which use the environment that was used to call the Builder for the
              target file.)

              b = Builder(action="build < $SOURCE > $TARGET")
              env = Environment(BUILDERS = {'MyBuild' : b})
              env.MyBuild('foo.out', 'foo.in', my_arg = 'xyzzy')

       chdir  A directory from which scons will execute the action(s) specified for this Builder.
              If  the  chdir  argument  is a string or a directory Node, scons will change to the
              specified directory.  If the chdir is not a string or Node and  is  non-zero,  then
              scons will change to the target file's directory.

              Note  that  scons  will  not  automatically  modify  its  expansion of construction
              variables like $TARGET and $SOURCE when using the chdir keyword argument--that  is,
              the  expanded  file  names  will  still  be  relative  to  the top-level SConstruct
              directory, and consequently incorrect relative to the  chdir  directory.   Builders
              created  using  chdir  keyword  argument,  will  need  to use construction variable
              expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename  portion
              of the targets and source.

              b = Builder(action="build < ${SOURCE.file} > ${TARGET.file}",
                          chdir=1)
              env = Environment(BUILDERS = {'MyBuild' : b})
              env.MyBuild('sub/dir/foo.out', 'sub/dir/foo.in')

       WARNING:  Python  only  keeps one current directory location for all of the threads.  This
       means that use of the chdir argument will not work  with  the  SCons  -j  option,  because
       individual  worker  threads  spawned  by  SCons  interfere with each other when they start
       changing directory.

       Any additional keyword arguments supplied when a Builder object is created (that is,  when
       the  Builder()  function  is called) will be set in the executing construction environment
       when the Builder object is  called.   The  canonical  example  here  would  be  to  set  a
       construction variable to the repository of a source code system.

       Any  additional  keyword  arguments  supplied when a Builder object is called will only be
       associated with the target created by that particular Builder call (and  any  other  files
       built as a result of the call).

       These  extra  keyword  arguments  are passed to the following functions: command generator
       functions, function Actions, and emitter functions.

   Action Objects
       The Builder() function will turn its action keyword argument into an appropriate  internal
       Action  object.   You  can  also explicity create Action objects using the Action() global
       function, which can then be passed to  the  Builder()  function.   This  can  be  used  to
       configure  an Action object more flexibly, or it may simply be more efficient than letting
       each separate Builder object create a separate Action when multiple Builder  objects  need
       to do the same thing.

       The  Action()  global function returns an appropriate object for the action represented by
       the type of the first argument:

       Action If the first argument is already an Action object, the object is simply returned.

       String If the first argument is a string, a command-line Action is  returned.   Note  that
              the  command-line  string may be preceded by an @ (at-sign) to suppress printing of
              the specified command line, or by a - (hyphen) to ignore the exit status  from  the
              specified command:

              Action('$CC -c -o $TARGET $SOURCES')

              # Doesn't print the line being executed.
              Action('@build $TARGET $SOURCES')

              # Ignores return value
              Action('-build $TARGET $SOURCES')

       List   If  the  first  argument  is a list, then a list of Action objects is returned.  An
              Action object is created as necessary for each element in the list.  If an  element
              within the list is itself a list, the internal list is the command and arguments to
              be executed via the command line.  This allows white space to  be  enclosed  in  an
              argument by defining a command in a list within a list:

              Action([['cc', '-c', '-DWHITE SPACE', '-o', '$TARGET', '$SOURCES']])

       Function
              If  the  first  argument  is a Python function, a function Action is returned.  The
              Python  function  must  take  three  keyword  arguments,  target  (a  Node   object
              representing  the target file), source (a Node object representing the source file)
              and env (the construction environment used for  building  the  target  file).   The
              target  and source arguments may be lists of Node objects if there is more than one
              target file or source file.  The actual target  and  source  file  name(s)  may  be
              retrieved from their Node objects via the built-in Python str() function:

              target_file_name = str(target)
              source_file_names = map(lambda x: str(x), source)

              The  function  should return 0 or None to indicate a successful build of the target
              file(s).  The function may raise an exception or return a non-zero exit  status  to
              indicate an unsuccessful build.

              def build_it(target = None, source = None, env = None):
                  # build the target from the source
                  return 0

              a = Action(build_it)

       If the action argument is not one of the above, None is returned.

       The second argument is optional and is used to define the output which is printed when the
       Action is actually performed.  In the absence of this  parameter,  or  if  it's  an  empty
       string,  a  default  output  depending  on the type of the action is used.  For example, a
       command-line action will print the executed command.  The argument must be either a Python
       function or a string.

       In  the  first  case,  it's a function that returns a string to be printed to describe the
       action being executed.  The function may also be specified  by  the  strfunction=  keyword
       argument.   Like  a  function  to  build  a  file,  this  function must take three keyword
       arguments: target (a Node object representing the target  file),  source  (a  Node  object
       representing the source file) and env (a construction environment).  The target and source
       arguments may be lists of Node objects if there is more than one  target  file  or  source
       file.

       In  the  second  case, you provide the string itself.  The string may also be specified by
       the cmdstr= keyword argument.  The string typically contains variables, notably $TARGET(S)
       and  $SOURCE(S),  or  consists  of  just  a  single  variable, which is optionally defined
       somewhere else.  SCons itself heavily uses the latter variant.

       Examples:

              def build_it(target, source, env):
                  # build the target from the source
                  return 0

              def string_it(target, source, env):
                  return "building '%s' from '%s'" % (target[0], source[0])

              # Use a positional argument.
              f = Action(build_it, string_it)
              s = Action(build_it, "building '$TARGET' from '$SOURCE'")

              # Alternatively, use a keyword argument.
              f = Action(build_it, strfunction=string_it)
              s = Action(build_it, cmdstr="building '$TARGET' from '$SOURCE'")

              # You can provide a configurable variable.
              l = Action(build_it, '$STRINGIT')

       The third and succeeding arguments, if present, may either be a construction variable or a
       list  of  construction  variables  whose  values  will be included in the signature of the
       Action when deciding whether a target should be rebuilt because the action  changed.   The
       variables may also be specified by a varlist= keyword parameter; if both are present, they
       are combined.  This is necessary whenever you want a target to be rebuilt when a  specific
       construction  variable  changes.   This  is  not  often needed for a string action, as the
       expanded variables will normally be part of the command line,  but  may  be  needed  if  a
       Python  function  action  uses  the  value  of a construction variable when generating the
       command line.

              def build_it(target, source, env):
                  # build the target from the 'XXX' construction variable
                  open(target[0], 'w').write(env['XXX'])
                  return 0

              # Use positional arguments.
              a = Action(build_it, '$STRINGIT', ['XXX'])

              # Alternatively, use a keyword argument.
              a = Action(build_it, varlist=['XXX'])

       The Action() global function can be passed the following  optional  keyword  arguments  to
       modify the Action object's behavior:

              chdir The chdir keyword argument specifies that scons will execute the action after
              changing to the specified directory.  If the  chdir  argument  is  a  string  or  a
              directory  Node,  scons  will  change  to  the  specified  directory.  If the chdir
              argument is not a string or Node and is non-zero, then scons  will  change  to  the
              target file's directory.

              Note  that  scons  will  not  automatically  modify  its  expansion of construction
              variables like $TARGET and $SOURCE when using the chdir keyword argument--that  is,
              the  expanded  file  names  will  still  be  relative  to  the top-level SConstruct
              directory, and consequently incorrect relative to the  chdir  directory.   Builders
              created  using  chdir  keyword  argument,  will  need  to use construction variable
              expansions like ${TARGET.file} and ${SOURCE.file} to use just the filename  portion
              of the targets and source.

              a = Action("build < ${SOURCE.file} > ${TARGET.file}",
                         chdir=1)

              exitstatfunc  The  Action()  global  function  also  takes  an exitstatfunc keyword
              argument which specifies a function that is  passed  the  exit  status  (or  return
              value)  from  the  specified  action and can return an arbitrary or modified value.
              This can be used, for example, to specify that  an  Action  object's  return  value
              should  be  ignored  under special conditions and SCons should, therefore, consider
              that the action always suceeds:

              def always_succeed(s):
                  # Always return 0, which indicates success.
                  return 0
              a = Action("build < ${SOURCE.file} > ${TARGET.file}",
                         exitstatfunc=always_succeed)

              batch_key The batch_key keyword argument can be used to specify that the Action can
              create  multiple  target  files  by  processing  multiple  independent source files
              simultaneously.  (The canonical example is "batch compilation" of  multiple  object
              files by passing multiple source files to a single invocation of a compiler such as
              Microsoft's Visual C / C++ compiler.)  If the batch_key argument is any  non-False,
              non-callable Python value, the configured Action object will cause scons to collect
              all targets built with the Action object and configured with the same  construction
              environment  into  single  invocations  of  the  Action  object's  command  line or
              function.   Command  lines  will  typically  want  to   use   the   CHANGED_SOURCES
              construction  variable  (and  possibly CHANGED_TARGETS as well) to only pass to the
              command line those sources that have actually  changed  since  their  targets  were
              built.

              Example:

              a = Action('build $CHANGED_SOURCES', batch_key=True)

       The  batch_key  argument  may  also be a callable function that returns a key that will be
       used to identify different "batches" of target files to be collected for  batch  building.
       A batch_key function must take the following arguments:

       action The action object.

       env    The construction environment configured for the target.

       target The list of targets for a particular configured action.

       source The list of source for a particular configured action.

              The  returned key should typically be a tuple of values derived from the arguments,
              using any appropriate logic to decide how multiple invocations should  be  batched.
              For  example,  a  batch_key  function  may decide to return the value of a specific
              construction variable from the env argument which will cause scons  to  batch-build
              targets  with  matching  values of that variable, or perhaps return the id() of the
              entire construction environment, in which case scons will batch-build  all  targets
              configured  with  the same construction environment.  Returning None indicates that
              the particular target should not be part of any batched build, but instead will  be
              built by a separate invocation of action's command or function.  Example:

              def batch_key(action, env, target, source):
                  tdir = target[0].dir
                  if tdir.name == 'special':
                      # Don't batch-build any target
                      # in the special/ subdirectory.
                      return None
                  return (id(action), id(env), tdir)
              a = Action('build $CHANGED_SOURCES', batch_key=batch_key)

   Miscellaneous Action Functions
       scons  supplies  a  number of functions that arrange for various common file and directory
       manipulations to be performed.  These are similar in concept to "tasks" in the  Ant  build
       tool,  although the implementation is slightly different.  These functions do not actually
       perform the specified action at the time the function is called,  but  instead  return  an
       Action  object  that  can  be  executed  at  the  appropriate  time.   (In Object-Oriented
       terminology, these are actually Action Factory functions that return Action objects.)

       In practice, there are two natural ways that these Action Functions  are  intended  to  be
       used.

       First,  if  you  need to perform the action at the time the SConscript file is being read,
       you can use the Execute global function to do so:
              Execute(Touch('file'))

       Second, you can use these functions to supply Actions in a list for  use  by  the  Command
       method.   This  can  allow  you to perform more complicated sequences of file manipulation
       without relying on platform-specific external commands: that
              env = Environment(TMPBUILD = '/tmp/builddir')
              env.Command('foo.out', 'foo.in',
                          [Mkdir('$TMPBUILD'),
                           Copy('$TMPBUILD', '${SOURCE.dir}'),
                           "cd $TMPBUILD && make",
                           Delete('$TMPBUILD')])

       Chmod(dest, mode)
              Returns an Action object that changes the permissions on the specified dest file or
              directory to the specified mode.  Examples:

              Execute(Chmod('file', 0755))

              env.Command('foo.out', 'foo.in',
                          [Copy('$TARGET', '$SOURCE'),
                           Chmod('$TARGET', 0755)])

       Copy(dest, src)
              Returns  an  Action  object  that will copy the src source file or directory to the
              dest destination file or directory.  Examples:

              Execute(Copy('foo.output', 'foo.input'))

              env.Command('bar.out', 'bar.in',
                          Copy('$TARGET', '$SOURCE'))

       Delete(entry, [must_exist])
              Returns an Action that deletes the specified entry,  which  may  be  a  file  or  a
              directory  tree.   If  a  directory is specified, the entire directory tree will be
              removed.  If the must_exist flag is set, then a Python error will be thrown if  the
              specified  entry  does  not exist; the default is must_exist=0, that is, the Action
              will silently do nothing if the entry does not exist.  Examples:

              Execute(Delete('/tmp/buildroot'))

              env.Command('foo.out', 'foo.in',
                          [Delete('${TARGET.dir}'),
                           MyBuildAction])

              Execute(Delete('file_that_must_exist', must_exist=1))

       Mkdir(dir)
              Returns an Action that creates the specified directory dir .  Examples:

              Execute(Mkdir('/tmp/outputdir'))

              env.Command('foo.out', 'foo.in',
                          [Mkdir('/tmp/builddir'),
                           Copy('/tmp/builddir/foo.in', '$SOURCE'),
                           "cd /tmp/builddir && make",
                           Copy('$TARGET', '/tmp/builddir/foo.out')])

       Move(dest, src)
              Returns an Action that moves the specified src file or directory to  the  specified
              dest file or directory.  Examples:

              Execute(Move('file.destination', 'file.source'))

              env.Command('output_file', 'input_file',
                          [MyBuildAction,
                           Move('$TARGET', 'file_created_by_MyBuildAction')])

       Touch(file)
              Returns  an  Action  that  updates  the  modification  time  on the specified file.
              Examples:

              Execute(Touch('file_to_be_touched'))

              env.Command('marker', 'input_file',
                          [MyBuildAction,
                           Touch('$TARGET')])

   Variable Substitution
       Before executing a command, scons performs  construction  variable  interpolation  on  the
       strings  that  make  up  the  command  line  of builders.  Variables are introduced by a $
       prefix.  Besides construction variables, scons provides the following variables  for  each
       command execution:

       CHANGED_SOURCES
              The  file  names  of  all  sources of the build command that have changed since the
              target was last built.

       CHANGED_TARGETS
              The file names of all targets that would be built from sources  that  have  changed
              since the target was last built.

       SOURCE The  file  name  of  the source of the build command, or the file name of the first
              source if multiple sources are being built.

       SOURCES
              The file names of the sources of the build command.

       TARGET The file name of the target being built, or the file name of the  first  target  if
              multiple targets are being built.

       TARGETS
              The file names of all targets being built.

       UNCHANGED_SOURCES
              The  file names of all sources of the build command that have not changed since the
              target was last built.

       UNCHANGED_TARGETS
              The file names of all targets that would  be  built  from  sources  that  have  not
              changed since the target was last built.

              (Note  that  the  above variables are reserved and may not be set in a construction
              environment.)

       For   example,   given   the   construction   variable   CC='cc',   targets=['foo'],   and
       sources=['foo.c', 'bar.c']:

              action='$CC -c -o $TARGET $SOURCES'

       would produce the command line:

              cc -c -o foo foo.c bar.c

       Variable  names  may  be  surrounded  by  curly  braces ({}) to separate the name from the
       trailing characters.  Within the curly braces, a variable name may  have  a  Python  slice
       subscript  appended to select one or more items from a list.  In the previous example, the
       string:

              ${SOURCES[1]}

       would produce:

              bar.c

       Additionally, a variable name may have the following special modifiers appended within the
       enclosing curly braces to modify the interpolated string:

       base   The  base  path  of  the  file name, including the directory path but excluding any
              suffix.

       dir    The name of the directory in which the file exists.

       file   The file name, minus any directory portion.

       filebase
              Just the basename of the file, minus any suffix and minus the directory.

       suffix Just the file suffix.

       abspath
              The absolute path name of the file.

       posix  The POSIX form of the path, with directories separated by / (forward  slashes)  not
              backslashes.  This is sometimes necessary on Windows systems when a path references
              a file on other (POSIX) systems.

       srcpath
              The directory and file name  to  the  source  file  linked  to  this  file  through
              VariantDir().   If  this  file  isn't  linked,  it  just  returns the directory and
              filename unchanged.

       srcdir The directory containing the source file linked to this file through  VariantDir().
              If this file isn't linked, it just returns the directory part of the filename.

       rsrcpath
              The  directory  and  file  name  to  the  source  file  linked to this file through
              VariantDir().  If the file does not exist locally but exists in a  Repository,  the
              path in the Repository is returned.  If this file isn't linked, it just returns the
              directory and filename unchanged.

       rsrcdir
              The Repository directory containing the source file linked  to  this  file  through
              VariantDir().  If this file isn't linked, it just returns the directory part of the
              filename.

       For example, the specified target will expand as follows for the corresponding modifiers:

              $TARGET              => sub/dir/file.x
              ${TARGET.base}       => sub/dir/file
              ${TARGET.dir}        => sub/dir
              ${TARGET.file}       => file.x
              ${TARGET.filebase}   => file
              ${TARGET.suffix}     => .x
              ${TARGET.abspath}    => /top/dir/sub/dir/file.x

              SConscript('src/SConscript', variant_dir='sub/dir')
              $SOURCE              => sub/dir/file.x
              ${SOURCE.srcpath}    => src/file.x
              ${SOURCE.srcdir}     => src

              Repository('/usr/repository')
              $SOURCE              => sub/dir/file.x
              ${SOURCE.rsrcpath}   => /usr/repository/src/file.x
              ${SOURCE.rsrcdir}    => /usr/repository/src

       Note that curly braces braces may also be used to enclose  arbitrary  Python  code  to  be
       evaluated.   (In  fact,  this  is how the above modifiers are substituted, they are simply
       attributes of the Python objects that represent TARGET, SOURCES, etc.)   See  the  section
       "Python Code Substitution" below, for more thorough examples of how this can be used.

       Lastly,  a  variable name may be a callable Python function associated with a construction
       variable in the environment.  The function should take four arguments: target - a list  of
       target  nodes,  source  -  a  list  of  source  nodes, env - the construction environment,
       for_signature - a Boolean value that specifies whether the function is  being  called  for
       generating a build signature.  SCons will insert whatever the called function returns into
       the expanded string:

              def foo(target, source, env, for_signature):
                  return "bar"

              # Will expand $BAR to "bar baz"
              env=Environment(FOO=foo, BAR="$FOO baz")

       You can use this feature to pass arguments to a Python function  by  creating  a  callable
       class  that  stores  one  or  more  arguments  in  an  object, and then uses them when the
       __call__() method is called.  Note that in this case, the entire variable  expansion  must
       be  enclosed  by  curly  braces  so  that  the  arguments  will  be  associated  with  the
       instantiation of the class:

              class foo(object):
                  def __init__(self, arg):
                      self.arg = arg

                  def __call__(self, target, source, env, for_signature):
                      return self.arg + " bar"

              # Will expand $BAR to "my argument bar baz"
              env=Environment(FOO=foo, BAR="${FOO('my argument')} baz")

       The special pseudo-variables $( and $) may be used to surround parts  of  a  command  line
       that  may  change  without  causing  a  rebuild--that  is,  which  are not included in the
       signature of target files built with this command.  All text between $(  and  $)  will  be
       removed  from  the  command  line before it is added to file signatures, and the $( and $)
       will be removed before the command is executed.  For example, the command line:

              echo Last build occurred $( $TODAY $). > $TARGET

       would execute the command:

              echo Last build occurred $TODAY. > $TARGET

       but the command signature added to any target files would be:

              echo Last build occurred  . > $TARGET

   Python Code Substitution
       Any python code within ${-} pairs gets evaluated by python 'eval', with the python globals
       set to the current environment's set of construction variables.  So in the following case:
              env['COND'] = 0
              env.Command('foo.out', 'foo.in',
                 '''echo ${COND==1 and 'FOO' or 'BAR'} > $TARGET''')
       the command executed will be either
              echo FOO > foo.out
       or
              echo BAR > foo.out
       according  to  the  current  value  of  env['COND']  when  the  command  is executed.  The
       evaluation occurs when the target is being built, not when the SConscript is  being  read.
       So if env['COND'] is changed later in the SConscript, the final value will be used.

       Here's  a  more  interesting example.  Note that all of COND, FOO, and BAR are environment
       variables, and their values are substituted into the final command.  FOO is a list, so its
       elements are interpolated separated by spaces.

              env=Environment()
              env['COND'] = 0
              env['FOO'] = ['foo1', 'foo2']
              env['BAR'] = 'barbar'
              env.Command('foo.out', 'foo.in',
                  'echo ${COND==1 and FOO or BAR} > $TARGET')

              # Will execute this:
              #  echo foo1 foo2 > foo.out

       SCons uses the following rules when converting construction variables into command lines:

       String When  the  value is a string it is interpreted as a space delimited list of command
              line arguments.

       List   When the value is a list it is interpreted as a list  of  command  line  arguments.
              Each element of the list is converted to a string.

       Other  Anything that is not a list or string is converted to a string and interpreted as a
              single command line argument.

       Newline
              Newline characters (\n) delimit lines. The newline parsing is done after all  other
              parsing,  so it is not possible for arguments (e.g. file names) to contain embedded
              newline characters. This limitation will likely go away  in  a  future  version  of
              SCons.

   Scanner Objects
       You  can  use  the  Scanner function to define objects to scan new file types for implicit
       dependencies.  The Scanner function accepts the following arguments:

       function
              This can be either: 1) a Python function that will  process  the  Node  (file)  and
              return  a  list  of  File Nodes representing the implicit dependencies (file names)
              found in the contents; or: 2) a dictionary  that  maps  keys  (typically  the  file
              suffix, but see below for more discussion) to other Scanners that should be called.

              If the argument is actually a Python function, the function must take three or four
              arguments:

                  def scanner_function(node, env, path):

                  def scanner_function(node, env, path, arg=None):

              The node argument is the internal SCons node representing the file.  Use  str(node)
              to  fetch  the  name  of the file, and node.get_contents() to fetch contents of the
              file.  Note that the file is not guaranteed to exist before the scanner is  called,
              so  the  scanner  function should check that if there's any chance that the scanned
              file might not exist (for example, if it's built from other files).

              The env argument is the construction environment for the scan.  Fetch  values  from
              it using the env.Dictionary() method.

              The  path  argument  is  a  tuple (or list) of directories that can be searched for
              files.  This will usually be the tuple returned by the path_function argument  (see
              below).

              The arg argument is the argument supplied when the scanner was created, if any.

       name   The name of the Scanner.  This is mainly used to identify the Scanner internally.

       argument
              An  optional  argument  that,  if specified, will be passed to the scanner function
              (described above) and the path function (specified below).

       skeys  An optional list that can be used to determine which scanner should be used  for  a
              given  Node.  In the usual case of scanning for file names, this argument will be a
              list of suffixes for the different file types that this Scanner knows how to  scan.
              If  the  argument  is a string, then it will be expanded into a list by the current
              environment.

       path_function
              A Python function that takes four or five arguments: a construction environment,  a
              Node for the directory containing the SConscript file in which the first target was
              defined, a list of target nodes, a list of source nodes, and an  optional  argument
              supplied  when  the  scanner  was  created.   The  path_function returns a tuple of
              directories that can be searched for files to be returned by this  Scanner  object.
              (Note  that  the  FindPathDirs()  function  can  be  used  to  return  a ready-made
              path_function for a given construction variable name, instead of  having  to  write
              your own function from scratch.)

       node_class
              The  class  of Node that should be returned by this Scanner object.  Any strings or
              other objects returned by the scanner function that are not of this class  will  be
              run through the node_factory function.

       node_factory
              A  Python  function  that  will  take a string or other object and turn it into the
              appropriate class of Node to be returned by this Scanner object.

       scan_check
              An optional Python  function  that  takes  two  arguments,  a  Node  (file)  and  a
              construction  environment, and returns whether the Node should, in fact, be scanned
              for dependencies.  This check can be used to eliminate  unnecessary  calls  to  the
              scanner  function when, for example, the underlying file represented by a Node does
              not yet exist.

       recursive
              An optional flag that specifies whether this scanner should be  re-invoked  on  the
              dependency  files  returned  by  the  scanner.  When this flag is not set, the Node
              subsystem will only invoke the scanner on the file  being  scanned,  and  not  (for
              example)  also  on  the  files  specified  by  the #include lines in the file being
              scanned.  recursive may be a callable function, in which case  it  will  be  called
              with a list of Nodes found and should return a list of Nodes that should be scanned
              recursively; this can be used to select a specific subset of Nodes  for  additional
              scanning.

       Note  that  scons  has  a  global  SourceFileScanner  object that is used by the Object(),
       SharedObject(), and StaticObject() builders to decide which scanner  should  be  used  for
       different  file  extensions.   You can using the SourceFileScanner.add_scanner() method to
       add your own Scanner object to the scons infrastructure that  builds  target  programs  or
       libraries from a list of source files of different types:

              def xyz_scan(node, env, path):
                  contents = node.get_text_contents()
                  # Scan the contents and return the included files.

              XYZScanner = Scanner(xyz_scan)

              SourceFileScanner.add_scanner('.xyz', XYZScanner)

              env.Program('my_prog', ['file1.c', 'file2.f', 'file3.xyz'])

SYSTEM-SPECIFIC BEHAVIOR

       SCons  and its configuration files are very portable, due largely to its implementation in
       Python.  There are, however, a few portability issues waiting to trap the unwary.

   .C file suffix
       SCons handles the upper-case .C file suffix differently, depending on the capabilities  of
       the  underlying  system.  On a case-sensitive system such as Linux or UNIX, SCons treats a
       file with a .C suffix as a C++ source file.  On a case-insensitive system such as Windows,
       SCons treats a file with a .C suffix as a C source file.

   .F file suffix
       SCons  handles the upper-case .F file suffix differently, depending on the capabilities of
       the underlying system.  On a case-sensitive system such as Linux or UNIX, SCons  treats  a
       file  with  a  .F  suffix  as  a  Fortran  source file that is to be first run through the
       standard C preprocessor.  On a case-insensitive system such as  Windows,  SCons  treats  a
       file  with  a  .F  suffix  as  a  Fortran source file that should not be run through the C
       preprocessor.

   Windows: Cygwin Tools and Cygwin Python vs. Windows Pythons
       Cygwin supplies a set of tools and utilities that let users work on a Windows system using
       a  more  POSIX-like  environment.   The Cygwin tools, including Cygwin Python, do this, in
       part, by sharing an ability to interpret UNIX-like path names.  For  example,  the  Cygwin
       tools will internally translate a Cygwin path name like /cygdrive/c/mydir to an equivalent
       Windows pathname of C:/mydir (equivalent to C:\mydir).

       Versions of Python that are built for native Windows execution, such as the python.org and
       ActiveState versions, do not have the Cygwin path name semantics.  This means that using a
       native Windows version of Python to build compiled programs using Cygwin  tools  (such  as
       gcc,  bison, and flex) may yield unpredictable results.  "Mixing and matching" in this way
       can be made to work, but it requires careful attention to the use of path  names  in  your
       SConscript files.

       In practice, users can sidestep the issue by adopting the following rules: When using gcc,
       use the Cygwin-supplied Python interpreter to run SCons; when using Microsoft Visual C/C++
       (or  some  other  Windows compiler) use the python.org or ActiveState version of Python to
       run SCons.

   Windows: scons.bat file
       On Windows systems, SCons is executed via a wrapper scons.bat file.  This has  (at  least)
       two ramifications:

       First, Windows command-line users that want to use variable assignment on the command line
       may have to put double quotes around the assignments:

              scons "FOO=BAR" "BAZ=BLEH"

       Second, the Cygwin shell does not recognize this file  as  being  the  same  as  an  scons
       command  issued  at the command-line prompt.  You can work around this either by executing
       scons.bat from the Cygwin command line, or by creating a wrapper shell script named  scons
       .

   MinGW
       The  MinGW  bin  directory  must be in your PATH environment variable or the PATH variable
       under the ENV construction variable for SCons to detect and  use  the  MinGW  tools.  When
       running  under  the  native  Windows Python interpreter, SCons will prefer the MinGW tools
       over the Cygwin tools, if they are both installed, regardless of  the  order  of  the  bin
       directories  in  the PATH variable. If you have both MSVC and MinGW installed and you want
       to use MinGW instead of MSVC, then you must explictly tell SCons to use MinGW by passing

              tools=['mingw']

       to the Environment() function, because SCons will prefer the MSVC  tools  over  the  MinGW
       tools.

EXAMPLES

       To help you get started using SCons, this section contains a brief overview of some common
       tasks.

   Basic Compilation From a Single Source File
              env = Environment()
              env.Program(target = 'foo', source = 'foo.c')

       Note:  Build the file by specifying the target as  an  argument  ("scons  foo"  or  "scons
       foo.exe").  or by specifying a dot ("scons .").

   Basic Compilation From Multiple Source Files
              env = Environment()
              env.Program(target = 'foo', source = Split('f1.c f2.c f3.c'))

   Setting a Compilation Flag
              env = Environment(CCFLAGS = '-g')
              env.Program(target = 'foo', source = 'foo.c')

   Search The Local Directory For .h Files
       Note:  You do not need to set CCFLAGS to specify -I options by hand.  SCons will construct
       the right -I options from CPPPATH.

              env = Environment(CPPPATH = ['.'])
              env.Program(target = 'foo', source = 'foo.c')

   Search Multiple Directories For .h Files
              env = Environment(CPPPATH = ['include1', 'include2'])
              env.Program(target = 'foo', source = 'foo.c')

   Building a Static Library
              env = Environment()
              env.StaticLibrary(target = 'foo', source = Split('l1.c l2.c'))
              env.StaticLibrary(target = 'bar', source = ['l3.c', 'l4.c'])

   Building a Shared Library
              env = Environment()
              env.SharedLibrary(target = 'foo', source = ['l5.c', 'l6.c'])
              env.SharedLibrary(target = 'bar', source = Split('l7.c l8.c'))

   Linking a Local Library Into a Program
              env = Environment(LIBS = 'mylib', LIBPATH = ['.'])
              env.Library(target = 'mylib', source = Split('l1.c l2.c'))
              env.Program(target = 'prog', source = ['p1.c', 'p2.c'])

   Defining Your Own Builder Object
       Notice that when you invoke the Builder, you can leave off the  target  file  suffix,  and
       SCons will add it automatically.

              bld = Builder(action = 'pdftex < $SOURCES > $TARGET'
                            suffix = '.pdf',
                            src_suffix = '.tex')
              env = Environment(BUILDERS = {'PDFBuilder' : bld})
              env.PDFBuilder(target = 'foo.pdf', source = 'foo.tex')

              # The following creates "bar.pdf" from "bar.tex"
              env.PDFBuilder(target = 'bar', source = 'bar')

       Note  also  that  the  above initialization overwrites the default Builder objects, so the
       Environment created above can not be used call Builders like env.Program(),  env.Object(),
       env.StaticLibrary(), etc.

   Adding Your Own Builder Object to an Environment
              bld = Builder(action = 'pdftex < $SOURCES > $TARGET'
                            suffix = '.pdf',
                            src_suffix = '.tex')
              env = Environment()
              env.Append(BUILDERS = {'PDFBuilder' : bld})
              env.PDFBuilder(target = 'foo.pdf', source = 'foo.tex')
              env.Program(target = 'bar', source = 'bar.c')

       You  also  can use other Pythonic techniques to add to the BUILDERS construction variable,
       such as:

              env = Environment()
              env['BUILDERS]['PDFBuilder'] = bld

   Defining Your Own Scanner Object
       The following example shows an extremely simple scanner (the kfile_scan()  function)  that
       doesn't  use a search path at all and simply returns the file names present on any include
       lines in the scanned file.  This would implicitly assume that all included files  live  in
       the top-level directory:

              import re

              include_re = re.compile(r'^include\s+(\S+)$', re.M)

              def kfile_scan(node, env, path, arg):
                  contents = node.get_text_contents()
                  includes = include_re.findall(contents)
                  return env.File(includes)

              kscan = Scanner(name = 'kfile',
                              function = kfile_scan,
                              argument = None,
                              skeys = ['.k'])
              scanners = Environment().Dictionary('SCANNERS')
              env = Environment(SCANNERS = scanners + [kscan])

              env.Command('foo', 'foo.k', 'kprocess < $SOURCES > $TARGET')

              bar_in = File('bar.in')
              env.Command('bar', bar_in, 'kprocess $SOURCES > $TARGET')
              bar_in.target_scanner = kscan

       It  is  important  to  note  that  you  have  to return a list of File nodes from the scan
       function, simple strings for the file names won't do. As in the examples  we  are  showing
       here, you can use the File() function of your current Environment in order to create nodes
       on the fly from a sequence of file names with relative paths.

       Here is a similar but more complete example that searches a path of directories (specified
       as the MYPATH construction variable) for files that actually exist:

              import re
              import os
              include_re = re.compile(r'^include\s+(\S+)$', re.M)

              def my_scan(node, env, path, arg):
                  contents = node.get_text_contents()
                  includes = include_re.findall(contents)
                  if includes == []:
                      return []
                  results = []
                  for inc in includes:
                      for dir in path:
                          file = str(dir) + os.sep + inc
                          if os.path.exists(file):
                              results.append(file)
                              break
                  return env.File(results)

              scanner = Scanner(name = 'myscanner',
                               function = my_scan,
                               argument = None,
                               skeys = ['.x'],
                               path_function = FindPathDirs('MYPATH')
                               )
              scanners = Environment().Dictionary('SCANNERS')
              env = Environment(SCANNERS = scanners + [scanner],
                                MYPATH = ['incs'])

              env.Command('foo', 'foo.x', 'xprocess < $SOURCES > $TARGET')

       The  FindPathDirs()  function  used in the previous example returns a function (actually a
       callable Python object) that will return a list of directories specified  in  the  $MYPATH
       construction variable. It lets SCons detect the file incs/foo.inc , even if foo.x contains
       the line include foo.inc only.  If you need to customize how the search path  is  derived,
       you  would  provide  your  own path_function argument when creating the Scanner object, as
       follows:

              # MYPATH is a list of directories to search for files in
              def pf(env, dir, target, source, arg):
                  top_dir = Dir('#').abspath
                  results = []
                  if 'MYPATH' in env:
                      for p in env['MYPATH']:
                          results.append(top_dir + os.sep + p)
                  return results

              scanner = Scanner(name = 'myscanner',
                               function = my_scan,
                               argument = None,
                               skeys = ['.x'],
                               path_function = pf
                               )

   Creating a Hierarchical Build
       Notice that the file names specified in a subdirectory's SConscript file are  relative  to
       that subdirectory.

              SConstruct:

                  env = Environment()
                  env.Program(target = 'foo', source = 'foo.c')

                  SConscript('sub/SConscript')

              sub/SConscript:

                  env = Environment()
                  # Builds sub/foo from sub/foo.c
                  env.Program(target = 'foo', source = 'foo.c')

                  SConscript('dir/SConscript')

              sub/dir/SConscript:

                  env = Environment()
                  # Builds sub/dir/foo from sub/dir/foo.c
                  env.Program(target = 'foo', source = 'foo.c')

   Sharing Variables Between SConscript Files
       You  must  explicitly  Export()  and  Import()  variables  that  you want to share between
       SConscript files.

              SConstruct:

                  env = Environment()
                  env.Program(target = 'foo', source = 'foo.c')

                  Export("env")
                  SConscript('subdirectory/SConscript')

              subdirectory/SConscript:

                  Import("env")
                  env.Program(target = 'foo', source = 'foo.c')

   Building Multiple Variants From the Same Source
       Use the variant_dir keyword argument to the SConscript function to establish one  or  more
       separate variant build directory trees for a given source directory:

              SConstruct:

                  cppdefines = ['FOO']
                  Export("cppdefines")
                  SConscript('src/SConscript', variant_dir='foo')

                  cppdefines = ['BAR']
                  Export("cppdefines")
                  SConscript('src/SConscript', variant_dir='bar')

              src/SConscript:

                  Import("cppdefines")
                  env = Environment(CPPDEFINES = cppdefines)
                  env.Program(target = 'src', source = 'src.c')

       Note  the use of the Export() method to set the "cppdefines" variable to a different value
       each time we call the SConscript function.

   Hierarchical Build of Two Libraries Linked With a Program
              SConstruct:

                  env = Environment(LIBPATH = ['#libA', '#libB'])
                  Export('env')
                  SConscript('libA/SConscript')
                  SConscript('libB/SConscript')
                  SConscript('Main/SConscript')

              libA/SConscript:

                  Import('env')
                  env.Library('a', Split('a1.c a2.c a3.c'))

              libB/SConscript:

                  Import('env')
                  env.Library('b', Split('b1.c b2.c b3.c'))

              Main/SConscript:

                  Import('env')
                  e = env.Copy(LIBS = ['a', 'b'])
                  e.Program('foo', Split('m1.c m2.c m3.c'))

       The '#' in the  LIBPATH  directories  specify  that  they're  relative  to  the  top-level
       directory, so they don't turn into "Main/libA" when they're used in Main/SConscript.

       Specifying  only  'a' and 'b' for the library names allows SCons to append the appropriate
       library prefix and suffix for  the  current  platform  (for  example,  'liba.a'  on  POSIX
       systems, 'a.lib' on Windows).

   Customizing construction variables from the command line.
       The  following  would  allow  the C compiler to be specified on the command line or in the
       file custom.py.

              vars = Variables('custom.py')
              vars.Add('CC', 'The C compiler.')
              env = Environment(variables=vars)
              Help(vars.GenerateHelpText(env))

       The user could specify the C compiler on the command line:

              scons "CC=my_cc"

       or in the custom.py file:

              CC = 'my_cc'

       or get documentation on the options:

              $ scons -h

              CC: The C compiler.
                  default: None
                  actual: cc

   Using Microsoft Visual C++ precompiled headers
       Since windows.h includes everything and the kitchen sink, it can take quite some  time  to
       compile  it  over  and  over  again  for  a bunch of object files, so Microsoft provides a
       mechanism to compile a set of headers  once  and  then  include  the  previously  compiled
       headers  in  any  object  file. This technology is called precompiled headers. The general
       recipe is to create a  file  named  "StdAfx.cpp"  that  includes  a  single  header  named
       "StdAfx.h",  and  then  include  every  header  you  want to precompile in "StdAfx.h", and
       finally include "StdAfx.h" as the first header in all the source files you  are  compiling
       to object files. For example:

       StdAfx.h:
              #include <windows.h>
              #include <my_big_header.h>

       StdAfx.cpp:
              #include <StdAfx.h>

       Foo.cpp:
              #include <StdAfx.h>

              /* do some stuff */

       Bar.cpp:
              #include <StdAfx.h>

              /* do some other stuff */

       SConstruct:
              env=Environment()
              env['PCHSTOP'] = 'StdAfx.h'
              env['PCH'] = env.PCH('StdAfx.cpp')[0]
              env.Program('MyApp', ['Foo.cpp', 'Bar.cpp'])

       For  more  information  see  the  document  for  the  PCH builder, and the PCH and PCHSTOP
       construction variables. To learn about the details of precompiled headers consult the MSDN
       documention for /Yc, /Yu, and /Yp.

   Using Microsoft Visual C++ external debugging information
       Since  including  debugging  information  in programs and shared libraries can cause their
       size to increase significantly, Microsoft provides a mechanism for including the debugging
       information  in  an  external file called a PDB file. SCons supports PDB files through the
       PDB construction variable.

       SConstruct:
              env=Environment()
              env['PDB'] = 'MyApp.pdb'
              env.Program('MyApp', ['Foo.cpp', 'Bar.cpp'])

       For more information see the document for the PDB construction variable.

ENVIRONMENT

       SCONS_LIB_DIR
              Specifies the directory that contains  the  SCons  Python  module  directory  (e.g.
              /home/aroach/scons-src-0.01/src/engine).

       SCONSFLAGS
              A  string  of options that will be used by scons in addition to those passed on the
              command line.

SEE ALSO

       scons User Manual, scons Design Document, scons source code.

AUTHORS

       Steven Knight <knight@baldmt.com>
       Anthony Roach <aroach@electriceyeball.com>

                                          September 2011                                 SCONS(1)