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NAME

       shape - identify and build program configurations from versions of source objects

SYNOPSIS

       shape
            [ -f <description file> ]
            [ -R <version selection rule> ] [ -V <variant name> ]
            [ -echo <macro name> ] [ -force <target> ] [ -rebuild <target> ]
            [ - dDehiknprs ]
            [ -bct ] [ -help ] [ -nomsg ] [ -novclass ] [ -version ] [ -xpoff ] [ -xpon ]
            [ target1 target2 ... ] [ macro=value ... ] [ macro+=value ... ]

DESCRIPTION

       Shape  allows  to  transparently  compile source objects that are either regular files, or
       source object versions in the  ShapeTools  version  object  base.  More  generally,  shape
       produces  a  set  of derived objects (``targets'') from appropriately selected versions of
       corresponding source objects according to a description of the  dependencies  between  the
       objects.  Shape  keeps track of the relevant parameters for compilations (source versions,
       compiler versions, compiler switches etc.) and thus provides a safe  and  efficient  build
       machinery.

       When  shape compiles source objects, it stores the resulting derived objects together with
       the effective compile parameters in  its  derived  object  cache.  Before  the  derivation
       process  for  a  requested  object is actually started, shape attempts to find an existing
       derived object that matches the requirements for the target, in the derived object  cache.
       Caching  and  restoring  of  objects  that  are  derived  from  immutable  versions allows
       developers to profit from previous builds by other team members. Overall compile costs  in
       projects are substantially reduced.

       When serving a build request, shape considers a possibly large number of versions that are
       stored for an object. Which particular version  is  bound  to  an  object's  name  in  the
       description file, is determined by version selection rules.

       Shape  can  manage  builds  of different variants of a system in parallel.  Shape uses the
       combined potential of dynamic version selection, dynamic macro redefinition,  and  derived
       object  management  to  handle  variant  builds. As most - if not all - of the objects and
       parameters involved in a build are defined as macros,  shape  provides  a  great  deal  of
       flexibility by allowing to alter some or all of the macros dynamically, depending on which
       variant shall be built. The concept of variant  definition  in  shape's  description  file
       offers a clear focal point for all definitions that are relevant for a certain variant.

OPTIONS

       -f <description file>
              shape uses the supplied argument as name of the description file to be used for the
              build. If no -f option is specified, shape tries to find a description  file  under
              one of the names ``Shapefile'', ``shapefile'', ``Makefile'', and ``makefile'' (from
              left to right). If no regular file with one  of  these  names  can  be  found,  but
              versions  of  respective files are available in the version object base, shape will
              use the most recent version.  When more than one  -f  <description  file>  argument
              pair  appears,  shape  reads  each  description  file  in turn.  If the name of the
              description file is specified as ``-'', shape will read the system description from
              standard  input.  It  is  possible to specify the description file in bound version
              notation, e.g. Shapefile[2.8] or  Shapefile[Release4]  (see  vbind(1)  for  details
              about bound version notation).

       -R <selection rule name>
              activates  the  specified  selection  rule  as  initial  version binding for source
              objects. If the -R option is present, and a selection rule is defined as the  first
              dependency  of  the  first target, shape will use the selection rule passed via the
              command line, and ignore the first (and only the first) selection  rule  activation
              within  the  description  file.  The  option  is useful to override initial default
              selection rules, specified within the description file, from the command line.

       -V <variant name>
              activates the variant  specified  by  <variant  name>.   Several  variants  can  be
              activated simultaneously from the command line by specifying the -V option multiple
              times. All variant specific definitions will be in effect as soon  as  shape  reads
              the corresponding variant definition in the description file.

       -force <target>
              forces  shape  to  build  the  specified  target  unconditionally,  i.e.  even if a
              suitable, previously build object exists.

       -echo <macro name>
              the value of the macro <macro name> is written to standard output. This  option  is
              useful  to  extract  information from the system description file (e.g. shape -echo
              SOURCES,  or  shape  -echo  SUBSYSTEMS),  or  to  control  the  effect  of  variant
              activations.

       -rebuild <target>
              attempt  a  precise  rebuild  of  target according to a bound configuration thread,
              supplied in a file named <target>.bct (see description of -bct switch).

       -d     run shape in debug mode. Print out detailed information about  object  dependencies
              and attributes.

       -D     print detailed information about the version binding process, and shape's reasoning
              regarding (re)builds of targets, or retrievals from the derived object cache.  This
              switch  is useful to find out about the exact reasons, why shape rederives a target
              (or not).

       -e     macro definitions that are  imported  from  the  environment  (see  description  of
              special macro IMPORT, below) override macro definitions in the description file (by
              default, macro definitions in the description file  have  precedence  over  imports
              from the environment).

       -h     print  usage  information on standard output (this is an abbreviation for the -help
              switch, see below).

       -i     ignore error codes returned by commands.

       -k     when a nonzero error status is returned by an invoked  command,  the  work  on  the
              current  target  is  abandoned  but shape continues with other branches that do not
              depend on the failed target.

       -n     no execution mode. Shape prints out commands,  but  does  not  execute  them.  Even
              command lines beginning with @ are printed. If a command contains the $(MAKE) macro
              reference, however, that line is always executed  in  order  to  allow  tracing  of
              recursive build processes.

       -p     print  out  the  complete  set  of macro definitions, target descriptions, and rule
              definitions, respectively.

       -r     do not  use  shape's  built-in  implicit  rules.  Implicit  rules  defined  in  the
              description file remain in effect.

       -s     run in silent mode. Shape does not print out the commands before executing them.

       -bct   record the build in a bound configuration thread file. A shape configuration thread
              contains precise definitions  of  all  source  versions,  their  dependencies,  the
              involved  tools,  and  related  options  that  were  in  effect  for  a  build. The
              configuration thread for a produced  toplevel  target  (the  first  target  in  the
              description  file, or a target requested from the command line) is stored in a file
              named <target>.bct. Bound configuration threads can be used as input  for  rebuilds
              (see  option  -rebuild,  above).  If  the  source version context of a bct-build is
              unsafe, shape will record that fact in the bct, and issue a warning message.

       -help  print usage information on standard output.

       -nomsg turn off the trace facility msg in version selection rules.

       -novclass
              disable checking for incompatibility of activated variants.

       -version
              print the version identification of the shape program.

       -xpoff turn off attribute expansion in source versions retrieved from the object base.  By
              default,  attribute expansion is turned on for all source objects that are directly
              retrieved from the object base, and turned off for source objects that are  regular
              files (see retrv(1) for details about attribute expansion).

       -xpon  turn  on  attribute  expansion  for  all  source objects, even in regular files. By
              default, attribute expansion is turned off for  source  objects  that  are  regular
              files,  and  turned  on for all source objects that are directly retrieved from the
              object base.

       target ...
              A list of target names can be passed to shape via the command line. If no target is
              given  on  the  command line, and the special target .DEFAULT is not defined within
              the description file, shape tries to  produce  the  first  target  defined  in  the
              description file.

       <macro definition>
              It  is possible to define or modify macros in the description file from the command
              line.  Macros that are defined this way take precedence over all other definitions.
              Command line macro definitions have either of two forms:

               NAME=VALUE
       and
               NAME+=VALUE

       with  NAME being a word and VALUE an arbitrary string. If VALUE contains white space, make
       sure to quote it.  The first form of command line  macro  definitions  sets  NAME  to  the
       substitution  VALUE. If VALUE is empty, the macro is reset.  The second form appends VALUE
       with a  leading  space  character  to  the  current  substitution  of  NAME.  The  current
       substitution  may  be  defined  in  the  description file, or by a previous setting on the
       command line. For details about the semantics of macro definitions and substitutions,  see
       the respective sections below.

DESCRIPTION FILES

       The  operation  of  shape  is controlled by a system description file (usually a Makefile)
       that provides structural information about the system to be managed. Other  than  make(1),
       shape  works  on  top of AtFS (Attributed File System), a repository of versioned objects,
       rather than plain files. Thus, genuine shape description files (usually called  Shapefile)
       feature  version selection rules, and variant definitions in addition to standard Makefile
       dependency rules.  Shape's description file is an upward compatible extension of make(1)'s
       description  file,  the  Makefile.   A useful structuring convention for shape description
       files is to maintain  a  Makefile,  and  a  Shapefile  in  parallel.  Only  genuine  shape
       constructs  (such  as  version  selection  rules,  or  variant  definitions)  are  kept in
       Shapefile, while the bulk of target rule- and macro definitions is kept in  Makefile.  The
       Makefile  shall  be  included  in Shapefile (see description of include directive, below).
       This structuring convention has the advantage that programs that were developed  with  the
       support of the ShapeTools system can be shipped as source distribution to sites that don't
       use ShapeTools.

       Although shape is largely downward compatible with the original make program, it should be
       noted  that  several  popular extensions of the original make program, such as GNU Make or
       Sun  Make,  provide  features  not  present  in  shape.   See   the   section   on   known
       incompatibilities below.

       The  description  file provides an ideal central information base for all sorts of product
       related  definitions.   Shape  encourages  the  development  of  a  set  of  (project-  or
       organization-specific)  conventions  for  system description, and provides a simple way to
       extract this information for use by other tools (see -echo option, above). The description
       file  syntax not only serves to specify component dependencies that are relevant for build
       processes, but allows a general, hierarchical definition of product oriented  tasks.   The
       concept  of  recursive  dependencies  maps  directly  to  a  stepwise  refinement  of task
       definitions. Such tasks can be fully, partly, or not  at  all  automated  as  appropriate.
       Thus,  certain  activities  may  be automated and standardized, while other activities are
       just informally described in  order  to  document  them  or  to  reason  about  them  (see
       shape_rms(1) for examples).

Syntactical Structure

       The basic syntactical structure of shape's description file is made up of:

       Comments
              Comments  begin  with  a  ``#''  character  and  extend  to the end of the line. In
              Shapefiles, the end of a line is defined as an unescaped newline  (``\<newline>''),
              or  the  end of the file. The comment character can't be escaped, but can be quoted
              in single- or double quotes. Comment characters in command lines  of  target  rules
              are ignored by shape.

       Directives
              Directives  are special keywords, known to shape. Directives begin at column 0 of a
              line and extend to the line end. Currently, the only directive recognized by  shape
              is

               include <list of file names>

       Macro Definitions
              Macro definitions have the general form:

               NAME <macro definition symbol> VALUE

       NAME  must  be  a single word consisting of a sequence of name characters. Name characters
       are all printable characters except the following:

                                        $ # : = ; <space> \t \n

       The macro definition symbol is either of ``='', ``+='', or ``:=''. VALUE is  an  arbitrary
       string terminated by the end of the line, or a comment. Macro definitions usually begin in
       the first column of a line, but may be  preceded  by  leading  <space>  characters.  Macro
       definitions  must  not contain leading <tab> characters (see section on Macro Definitions,
       below, for more details).

       Macro References
              Macro references have one of the following forms:

               $(<macro name>)
               ${<macro name>}
               $<single character name>

       The macro substitution operator (``$'') can't be escaped, but can be  represented  by  the
       substitution ``$$''. Macro substitution occurs anywhere in the description file, except in
       comments, macro names, left hand sides of version selection rule- and  variant  definition
       headers  (see  next  section),  and  variant  class  definitions  (see  section  on  Macro
       Substitutions, below, for more details).

       Rules  Rules are made up from a rule header, and an optional rule body.  The  rule  header
              consists  of a left hand side, a rule definition symbol, and an optional right hand
              side. The left hand side usually begins in column 0 of a line, and may be  preceded
              by  leading  <space>  characters.  Left hand sides of rule headers must not contain
              leading <tab> characters. The optional right hand side of a rule header extends  to
              the  end  of  the  line, or the beginning of the rule body. A rule body consists of
              consecutive lines beginning  with  a  <tab>  character.  The  body  of  a  rule  is
              terminated by the next line not beginning with a <tab> character, or the end of the
              file.

              Shape recognizes three different kinds of rules, distinguished by their  respective
              rule definition symbols:

              •
                target  rules.  Target  rules  have  a  single  colon  character  (``:'') as rule
                definition symbol.  The left hand  side  of  target  rule  headers  is  a  space-
                separated  list  of  names.  The  optional  right  hand side consists of a space-
                separated list of names, followed by an optional list of  production  ingredients
                (see section on Target Rules, below).

              •
                version  selection rules. Version selection rules have the rule definition symbol
                ``:-''. The rule header of version selection rules has a single word on its  left
                hand  side,  and  no  right  hand  side  (see section on Version Selection Rules,
                below).

              •
                variant definitions. Although variant definitions are - as the  name  suggests  -
                definitions,  not  rules  (from  a  semantical  view  point),  their  syntactical
                representation is that of a rule. Variant definitions have  the  rule  definition
                symbol  ``:+''.  The rule header of a variant definition has a single word on its
                left hand side, and no right hand  side  (see  section  on  Variant  Definitions,
                below).

       Variant Class Definitions
              Variant class definitions have the form

                              vclass <name> ::= (variant1, variant2, ...)

       (see section on Variants, below).

       Line Continuations
              If  the  end  of  an  input line is escaped by a backslash (``\'') the next line is
              considered as a continuation line. The  backslash  newline  character  sequence  is
              replaced by a space.

Macro Definitions

       Macro  definitions associate names with strings that will be substituted wherever the name
       of the macro is referenced (see next section). Macros are useful for writing maintainable,
       and  somewhat  generic  description  files.  Even  moderately  large projects will find it
       extremely rewarding  to  define  conventions  for  naming  and  usage  of  certain  macros
       throughout the product description file.

       There are three different kinds of macro definitions:

       Simple Macro Definitions

       A simple macro definition looks like

               NAME = <any string>

       The string that is associated with the macro name can contain macro references. If a macro
       is defined multiple  times  within  a  description  file,  the  last  definition  will  be
       effective. Macros defined on the command line take precedence over definitions of the same
       macro in the description file.

       Additive Macro Definitions

       This type of macro definition looks like

               NAME += <any string>

       The string on the right hand side of the definition is  appended  to  any  existing  value
       associated  with NAME, separated by a space character. Multiple additive macro definitions
       are concatenated in the order in which they appear in the description file. If an additive
       macro  definition  occurs  on  the  command  line,  the  last  string value defined in the
       description file is prepended to the string value defined on the  command  line.  Additive
       macro  definitions  in  the  description file are appended to string values defined on the
       command line.

       Evaluative Macro Definitions

       Evaluative macros are defined in the following way:

               NAME := <any string>

       First, the string value is associated to  NAME  in  the  same  way  as  for  simple  macro
       definitions.  When  NAME  is  substituted  for  the first time, the right hand side of the
       definition is evaluated, and the result of this evaluation replaces  the  original  string
       value  associated  with NAME. Thus, evaluation of the right hand side occurs exactly once.
       This is particularly useful if the defining string is a  command  substitution  (see  next
       section).

Macro Substitutions

       Macro  substitution  is  the process of substituting a macro reference by the string value
       associated with a macro name.  References to undefined macros are substituted by an  empty
       string. Macro references have either of the forms:

               $(NAME)
               ${NAME}
               $<any single character>

       The following are valid macro references:

               $(CFLAGS)
               $7
               ${SOURCE-FILES}
               $(X)
               $X

       The last two references have identical substitutions. The macro reference

               $$

       will substitute a single dollar sign.

       Before  a  macro  reference  is  substituted,  the  associated  string  will be evaluated.
       Evaluation of a string value includes

       -
         substitution of all macro references in the string value

       -
         command substitution. Any substring of the string value enclosed in  backquotes  (```'')
         will  be  passed  as  command  to  the  shell, and be replaced by the command's standard
         output.

       -
         string substitution. If a macro reference has the form

               $(NAME:<old>=<new>)

       the reference will be substituted by the evaluated value of NAME, with all occurrences  of
       the  string  <old>  replaced  by the string <new>. This is particularly useful to maintain
       related lists, such as CSOURCES and OBJECTS for example, automatically:

               CSOURCES := `echo *.c`
               OBJECTS := $(CSOURCES:.c=.o)

       Shape substitutes macro references as late as possible. Macro references  occurring  in  a
       macro  definition are only substituted when the defined macro itself is substituted. Macro
       references on the dependencies side of target rules  are  substituted  when  the  rule  is
       evaluated. Macro references on the target side of target rules are substituted immediately
       after shape has read the description file, i.e. before any production  is  started.  Macro
       references  in  include  directives  are  substituted when the directive is executed while
       shape reads the description file.

Built-in and Special Purpose Macros

       In order to provide parametrization of  shape's  built-in  implicit  rules,  a  number  of
       predefined  macros  is supplied by convention. These macros have meaningful initial values
       that can be altered by the user. There are also several macros that have  special  meaning
       for shape.

       Macro       Purpose            Initial value   Remark

       @           full name of the current           <dynamic>special
                   target

       ?           list of target dependencies        <dynamic>special

       <           name of the first target           <dynamic>special
                   dependency

       *           prefix shared by target            <dynamic>special
                   and the dependent filenames

       #           bound version id of the current    <dynamic>special
                   dependency

       $           the character ``$''                $<special>

       +           name of object to be bound         <dynamic>special
                   to a version (selection rules
                   only!)

       AS          Program for doing assembly         asconventional

       ASFLAGS     Flags for the assembler            <none>conventional

       CC          Program for compiling C            ccconventional
                   programs

       CFLAGS      Flags for the C compiler           <none>conventional

       FC          Program for compiling Fortran      f77conventional
                   programs

       FFLAGS      Flags for the Fortran compiler     <none>conventional

       HOSTTYPE    Host architecture of the           <none>special
                   computer that runs shape.
                   The value of this macro is
                   used by shape to construct
                   the derivation key attribute
                   for derived objects

       IMPORT      List of environment variables      <none>special
                   that shall be imported as
                   macro definitions

       LD          Program to link programs           ldconventional

       LDFLAGS     Flags for the linker               <none>conventional

       LEX         Program to turn Lex grammars       lexconventional
                   into C or Ratfor programs

       LFLAGS      Flags for the lexical analyzer     <none>conventional
                   lex

       LOGNAME     The name or network-id under       <dynamic>special
                   which the user who owns the
                   shape process is logged on

       M2C         Program for compiling Modula2      m2cconventional
                   programs

       M2FLAGS     Flags for the Modula2 compiler     <none>conventional

       MAKE        The command line with which        shape $(MAKEFLAGS)special
                   shape has been invoked.
                   This macro is used for
                   recursive calls to shape

       MAKEFLAGS   Command line flags relevant        <defined fromspecial
                   for recursive calls to shape       command line>

       PC          Program for compiling Pascal       pcconventional
                   programs

       PFLAGS      Flags for the Pascal compiler      <none>conventional

       RFLAGS      Flags for the Fortran compiler     <none>conventional
                   for Ratfor programs

       SHAPEPID    The process id of the              <dynamic>special
                   running shape program

       SHAPEVERSION                   The version id of theshape_CM-4.4special
                   shape program      (or above)

       SHELL       The command processor for          /bin/shspecial
                   the target rule command
                   lines. The referenced command
                   processor must be able to
                   take its commands  from
                   standard input (see section
                   on Command execution,
                   below)

       VPATH       Search path extension for          <none>special
                   localizing source components

       YACC        Program to turn Yacc grammars      yaccconventional
                   into C programs

       YFLAGS      Flags for yacc     <none>          conventional

       vpath       Dynamic search path extension      <none>special
                   for variants of source components

       The  function  of  the special purpose macros HOSTTYPE, IMPORT, MAKE, VPATH, and vpath are
       described in the sections on OPERATION, and Variants below.

Target Rules

       A target rule defines how, and under what conditions a target is derived  from  a  set  of
       source  objects and/or other targets. A target is a name that can refer to a file but need
       not to do so.  Target rules have the following format:

               <target>... : [<version binding>] [+<variant>...] [<dependency>...] \
                       [: <ingredient>...] [; <command>]
                       \t[<command>]
                       ...

       The header of a target rule (see Syntactical Structure,  above)  consists  of  a  list  of
       targets,  terminated  by  a  colon,  followed  by an optional list of dependencies, and an
       optional list of production ingredients, beginning after a second  colon  character.   The
       rule  header  is terminated by a newline or a semicolon, and followed by the optional rule
       body. The rule body consists of command lines that are executed when a target needs to  be
       rederived.   The  first  command line may immediately follow the semicolon that terminates
       the rule header. Subsequent command lines must begin with a <tab>  character.  The  target
       rule  body  is terminated by the first line that doesn't begin with a <tab>, or by the end
       of the file.

       Targets

       When multiple targets appear on the left hand side of a rule header,  and  the  derivation
       process needs to be started, shape will derive all of the targets in a single run.

       Dependencies

       Shape  checks a target's dependencies from left to right. The first dependency is examined
       whether it is the name of a version selection rule. If it is,  shape  sets  the  selection
       rule  active (eclipsing all previous selection rule activations), and proceeds to the next
       dependency. Next, shape checks whether the dependency is  a  variant  activation.  If  the
       dependency starts with a ``+'' character followed by the name of a variant, the variant is
       activated (see the section on Variants,  below).  Shape  proceeds  to  check  for  variant
       activations  until  the  first  dependency that isn't a variant activation is found. Next,
       shape proceeds through the list of remaining dependencies, and binds (or derives) each  of
       them  as  necessary,  performing  a depth first traversal of the dependency graph (see the
       section on OPERATION, below).

       Production Ingredients

       After all dependencies have been bound,  shape  constructs  the  derivation  key  for  the
       target.  The  derivation  key  is an attribute that defines the complete set of parameters
       that determine whether a target needs to be rebuild. Besides all bound  dependencies,  the
       derivation  key contains the production ingredients that were specified in the target rule
       header. Production ingredients are typically complete definitions of the macros  that  are
       referenced  in  the  command  lines  of  the rule's body. Thus, tool versions and switches
       affecting the operation of a tool can be made part  of  the  derivation  parameters  of  a
       target.  In  order  to  include macro definitions into the derivation key of a target, the
       special reference

               +(NAME1) +(NAME2) ...

       must occur in place of the production ingredients.

       Command Lines

       When shape concludes that a target needs to be (re-)derived, the commands  in  the  target
       rule  body  are  executed. The rule body consists of consecutive lines that are treated as
       separate commands. Each command line is evaluated as described in  the  section  on  Macro
       Substitution,  above,  and  passed  to the command interpreter defined by the macro SHELL.
       Each command line is executed as a separate process. If complex commands are  needed  that
       don't  fit  on  a single line, or if the overhead of repeated process invocations shall be
       avoided, a logical command line can be extended by escaping the newline with  a  backslash
       character (\<newline>), and continuing it on the next physical line.

       Command lines may be preceded by one or two special characters:

       -      shape ignores any nonzero error code returned by a command line for which the first
              character is a minus sign. The minus sign is  not  passed  to  the  shell.  When  a
              command  returns  a  nonzero  return status, shape usually considers the derivation
              process for the target as failure and terminates, unless the -i or -k switches,  or
              the .IGNORE special target is in effect.

       @      If  the  first  character of a command is a ``@'', shape does not print the command
              before executing it. The ``@'' is not passed to the shell.

       @-     If the first two non-<tab> characters are  ``@-'',  shape  ignores  nonzero  return
              codes, and suppresses the printing of the command line.

       If  shape is invoked in no execution mode (-n), the evaluated command lines are printed on
       standard output, showing what shape would do if invoked without  -n.  Command  lines  that
       contain  the  macro reference $(MAKE) are always executed, even if -n is set. This is done
       to allow simulation of recursive builds that may span over subdirectories.  The  reference
       $(MAKE)  is  substituted  by  a  shape  command  invocation with all relevant command line
       switches set.

       Within command lines of the rule body, some  parts  of  the  target  rule  header  can  be
       dynamically  referenced. When a command line is evaluated, the following substitutions are
       possible

       Reference   Substitution
       $@          full name of the current target
       $?          list of dependencies
       $<          name of the first dependency
       $*          prefix shared by current and the dependent filenames
       $#          bound version id of the current dependency
                   (implicit rules only)

Implicit Rules

       Shape's target rules come in two different flavors: explicit, and implicit. Implicit rules
       can  be seen as templates that define dependency patterns which apply to most targets of a
       given kind. For this reason, implicit rules are  sometimes  called  pattern  rules.  Shape
       converts make's old-style implicit rules (e.g.  .c.o:) to pattern rules while it reads the
       description file.  A typical dependency pattern is, for example, the dependency  of  files
       containing  linkable  object  code, e.g. module.o to corresponding files containing source
       code, e.g. module.c. The derivation process for most  of  these  source/derived  pairs  is
       identical.   Rather  than  writing separate rules for all source/derived dependencies of a
       system, it is possible to write a single, generic rule, called implicit rule.  An implicit
       rule has the following format:

               %[.<suff1>] %[.<suff2>] ... : %[.<suff3>] %[.<suff4>]... \
                   [: <ingredient>...] [; <command>]
                   \t[<command>]
                   \t[<command>]
                   ...

       While the structure of implicit rules is the same as described above, the names of targets
       and dependencies are replaced by target patterns, and dependency  templates  respectively.
       The  percent character in a target pattern acts as wildcard that is matched against all of
       a target's name up to the optional trailing suffix. For shape, an object  name  suffix  is
       the  sequence of characters enclosed by the last period character (``.'') within the name,
       and the <space> character terminating the name. The following example illustrates  shape's
       concept of suffixes:

           Name        Suffix
           sample.cde  cde
           sample.x.y.cc
           sample_c
           .sample.c   c

       The  following  is  an example for an implicit rule that derives linkable object code from
       corresponding C source files:

           %.o : %.c : +(CC) +(CFLAGS)
               \t@echo shape - executing: $(CC) -c $(CFLAGS) $#;
               \t@$(CC) $(CFLAGS) -E %.c |
                 sed 's;^\(# [0-9][0-9]* \"\)%.c\(\".*\)$$;e1$#\2;' > %.i;
               \t@$(CC) -c $(CFLAGS) %.i;
               \t@rm %.i;

       NOTE: This rule is shape's built-in implicit rule to compile C source files.  The  cryptic
       command  sequence  has  the purpose to encode the complete file version id into the object
       code (e.g. sample.c[3.4] rather than sample.c). This is extremely  useful  in  conjunction
       with  with  the  -g  switch  of most C compilers, and version sensitive debuggers, such as
       vgdb.

       If a target is derived using implicit rules, the name of the target is matched against the
       target  patterns  of  the  implicit  rules. If a rule matches, the matching portion of the
       target name (the stem, referred to by the ``%'') is consistently substituted for all other
       occurrences of the wildcard character throughout the rule. Once this is done, the implicit
       rule is treated like an explicit target rule.

Explicit Rules

       Explicit rules associate explicit target names with explicit dependencies.  Explicit rules
       are  most typically used to specify dependencies that cannot be covered by implicit rules,
       such as deriving an executable program by linking  many  object  code  modules.   In  many
       cases,  explicit  rules  are  used  to specify only those target dependencies that are not
       implied by an implicit rule (such as include dependencies for  object  files),  while  the
       ``natural'' dependencies are assumed as being present. If a description file contains only
       this sort of explicit dependencies, the omitted implicit dependencies (and  an  applicable
       rule body) are automatically added by shape to the total list of target dependencies.

Built-in Implicit Rules

       Shape  provides  a  number  of  predefined  implicit  target  rules that cover many common
       source/target derivations. The following  table  lists  target  patterns,  and  dependency
       templates for shape's built-in implicit rules.

       Target      Dependency  Derivation
       %.a         %.c         Compile archive library from C source
       %.c         %.l         Generate C programs from Lex grammar
       %.c         %.y         Generate C programs from Yacc grammar
       %.o         %.l         Compile object code from Lex grammar
       %.o         %.y         Compile object code from Yacc grammar
       %.o         %.s         Translate assembler program to object code
       %.o         %.r         Compile Ratfor source
       %.o         %.F         Compile Fortran source
       %.o         %.f         Compile Fortran source
       %.sym       %.def       Compile Modula definition modules
       %.o         %.mod       Compile Modula implementation modules
       %.o         %.p         Compile Pascal source
       %.o         %.c         Compile C source
       %           %.sh        Make executable program from shell-script
       %           %.r         Build executable program from Ratfor source
       %           %.F         Build executable program from Fortran source
       %           %.f         Build executable program from Fortran source
       %           %.p         Build executable program from Pascal source
       %           %.mod       Build executable program from Modula source
       %           %.c         Build executable program from C source

       For a complete definition of shape's built-in implicit rules, run shape -p.

Special Purpose Targets

       Several aspects of shape's operation are controlled by special purpose targets that can be
       put into the description file. Special purpose targets by convention begin with  a  period
       character, and have no associated commands.

       Target      Purpose

       .DEFAULT:   commands  in  the  rule  body of the .DEFAULT target rule are executed for all
                   targets that cannot be derived by explicit or implicit  target  rules.  If  no
                   commands  at all shall be executed for a rule but .DEFAULT is needed for other
                   targets, that rule can be given an empty command (either a ``;'' at the end of
                   the  rule  header,  or  an  empty  line beginning with <tab>). If .DEFAULT has
                   dependencies, and no targets  are  requested  from  the  command  line,  these
                   dependencies  are  treated  as if they were targets requested from the command
                   line.

       .IGNORE:    causes shape to ignore non zero return codes of invoked commands.   Equivalent
                   to the -i switch

       .SILENT:    silent  command execution. The command lines are not printed before execution.
                   Equivalent to the -s switch

       .BPOOL:     only the dependencies associated with this target are stored  in  the  derived
                   object cache

       .NOBPOOL:   dependencies  associated with this target are not stored in the derived object
                   cache.

       If both, .BPOOL, and .NOBPOOL are defined, only the  difference  set  of  both  dependency
       lists will be stored in the derived object cache.

Version Selection Rules

       When  shape  builds  a target, it uses version selection rules to bind a unique version to
       each name of the prerequisite source objects. Version selection rules consist of  a  name,
       and an associated set of predicate lists in the rule body. The format of version selection
       rules is:
               <name> [( <arg1>, <arg2>,...)] :-
                   \t[<pattern1>,] <pred1> (...), <pred2> (...);
                   \t[<pattern2>,] <pred1> (...), <pred2> (...);
                   ...
                   \t.
       The body of a version selection rule consists of a sequence of alternatives, separated  by
       semicolons. Each of the alternatives is an optional pattern, followed by a comma-separated
       list of predicates. The selection rule is terminated by a period character. The semicolon-
       separated  sequence  of  alternatives in a version selection rule constitutes a logical OR
       expression. The comma-separated list of predicates in an alternative constitutes a logical
       AND expression.

       Version Binding

       Version binding is the process of determining exactly one version of a given source object
       from the set of all available versions. Version binding is said to succeed if one  of  the
       rule  alternatives succeeds. An alternative succeeds, if it leads to the identification of
       exactly one version. It is said to fail otherwise.  When shape binds a version to the name
       of  a  source object, it tries each alternative with a matching pattern, until the name is
       unambiguously bound to a version. If the pattern is omitted, the alternative will be tried
       unconditionally.

       The  functioning  of  version  selection  rules is one of shape's most important, yet most
       subtile aspects. In order to provide  a  basis  for  an  intuitive  understanding  of  the
       selection rule mechanism, an example is described. The rule most_recent, below, binds:
       - files that were checked out for modification by the shape-invoking user
       - versions of files that were recently modified (→ status saved) by the same user
       - the most recently proposed version (→ status proposed) of files modified by other users,
       - or the file version from the last release.

           LASTRELEASE := `lastrelease`# "lastrelease" returns the name
                                    # of the last release
           most_recent :-
               eq (status, busy), exists ($+[locked_by($(LOGNAME)):]);
               ge (status, saved), max (mtime),
                 max (version), eq (author, $(LOGNAME));
               ge (status, proposed), max (mtime),
                 max (version);
               eq (__SymbolicName__, $(LASTRELEASE));
               cut ($_rule$: couldn't bind $+ as requested!).

           locked_by (user_id) :-
               max (version), eq (locker, $_user_id$).

       For  a more detailed description of version selection rule syntax, semantics, and the list
       of built-in predicates, see BindRules(7).

       Activation of Version Selection Rules

       A version selection for a certain  target  is  invoked  by  specifying  the  name  of  the
       selection  rule  as first dependency of a target, or by supplying a selection rule name as
       argument to the -R option.  If no selection rule is specified explicitly, shape  uses  its
       built-in  version  selection  rule  that  tries to bind a regular file, or the most recent
       version to the name of an object.

Variants

       The term variant refers to the intention  to  manage  a  product  that  must  comply  with
       different  sets  of  varying external constraints as a unit. Independently from particular
       semantics that might be associated with the variant notion, there exists a small number of
       techniques to implement software variation on a technical level. These techniques are:

       physical separation of variant components. This is achieved by maintaining separate copies
       of components in different directories, or by maintaining  variant  specific  branches  in
       version control systems;

       source preprocessing of variant components. With this technique, multiple logical variants
       of a source  component  are  maintained  in  a  single  file  that  contains  preprocessor
       instructions.  Before a particular variant can be accessed, a preprocessor must extract it
       from the common source. A popular example of this technique  is  conditional  compilation,
       controlled by the #if, and #ifdef instructions within the domain of C/C++ programming;

       composition  variation of complex product variants. This technique addresses the case when
       different variants of a complex product (such as a program) are  composed  from  different
       sets of components;

       derivation  variation  (or  variation  of the process) that produces different variants of
       derived objects from the same set of sources by modifying  parameters  of  the  derivation
       process.  A  typical  example  for  this case is cross compilation of the same sources for
       different target  platforms,  or  code  instrumentation  for  various  purposes,  such  as
       debugging, testing, profiling, or optimization.

       Depending  on  the  particular  needs  of  a  project,  all  of these techniques may be in
       simultaneous use, and can occur intermixed  as  appropriate.  Shape  allows  to  associate
       logical  variant  names  with a set of definitions that control all of the above mentioned
       techniques, making it possible to  request  builds  of  particular  system  variants  (and
       combinations  of  compatible  variants) without the need to worry about how these variants
       are realized technically.

Variant Definitions

       Shape derives its flexibility from  using  macro  substitution  in  the  description  file
       wherever  possible.  Shape  variant  definitions are basically groups of macro definitions
       that take effect when the variant is activated for a build. A variant definition  has  the
       following format:

               <variant-name> :+
                   \t<Macro name1>=<Value>
                   ...

       When  a  variant  is  activated,  the macro definitions associated with the variant become
       effective. Any previous definition of a macro made in the  description  file,  or  on  the
       command  line  is  replaced  by  the  variant macro substitution. If a macro is defined in
       several variants that are activated together, the respective values are concatenated.

       Locating physically separate Variant Source Objects

       Shape provides a special macro, vpath, that is intended to be used in variant definitions.
       The  vpath  macro  defines  shape's  search  precedence  when  source version archives are
       located. If vpath is non-empty, shape tries to find any referenced source  object  in  the
       vpath  directories  first.  If several activated variants define vpath, the variant search
       path is concatenated and searched from right to left, i.e.  the last variant that has been
       activated  has precedence. Only if a referenced source component cannot be found in any of
       the vpath directories, the current directory is searched.  If a  source  object  has  been
       found,  it  will  be  bound  by  the  current  version  selection rule, and be temporarily
       installed in the build directory. This means that components which  are  maintained  in  a
       vpath  subdirectory  are  temporarily  moved  up  to  the  main directory. Thus, it is not
       necessary to make any reference to a vpath subdirectory path in the target rules.

       Variant Activation

       When a product is configured and built, variants are typically activated  by  supplying  a
       variant name as argument to the -V options.

       Variants can also be activated for a given target by specifying respective, ``+''-prefixed
       variant names as dependencies (see section on Target Rules,  above).  Variant  activations
       for  a  target  must  occur  before any real object dependency on the dependency line, and
       after the optional version selection rule activation.

Variant Class Definitions

       With  Variant  class  definitions,  shape  offers  a  construct  that  allows  to   define
       incompatible  variants,  i.e.  variants  that  cannot  be  activated simultaneously. Shape
       variant class definitions have the following format:

               vclass <variant-class-name>  ::= ( <var1>, <var2> ...)

       The same variant name can occur in multiple variant class definitions.  If  a  combination
       of  variants  is  requested with any two variant names that are member of the same variant
       class, shape will issue an error message, and terminate. Checking of variant  classes  can
       be disabled by specifying the -novclass switch on the command line.

       NOTE:  variant  class  definitions  must  occur in the description file before any variant
       definition referenced in  a  variant  class.   Variant  classes  that  are  defined  after
       referenced variants cannot enforce mutual exclusion of incompatible variants.

       An Example

       The  following  example  shall  illustrate  the  use  of  variant definitions, and variant
       classes:

           vclass compiler ::= (gnu, prop)

           gnu:+
               CC = gcc -Wall
               OPTIMIZE = -O2 -inline-functions
               DEBUG = -g -g3
               PROFILE = -pg -a
               STDC = -ansi

           prop:+
               CC = cc
               OPTIMIZE = +O3
               DEBUG = -g -z +Y
               PROFILE = -G
               STDC = -Aa

           vclass quality ::= (debug, profile, optimize)

           debug:+
               VARCFLAGS = $(DEBUG)

           profile:+
               VARCFLAGS = $(PROFILE)

           optimize:+
               VARCFLAGS = $(OPTIMIZE)

           CFLAGS += $(VARCFLAGS)

       If a variant requires the modification of macros with predefined meaning, it is  sometimes
       a  good idea not to redefine the macro itself in the variant section. In such a case it is
       possible to augment an existing macro value by using  shape's  additive  macro  definition
       facility, and a macro from the variant definition defined for this purpose (e.g. VARCFLAGS
       in the example above).

OPERATION

       When invoked, shape first parses the command line. Shape records the names of the variants
       to  be  activated  from  the  command  line via the -V option. Next, shape initializes the
       built-in, and special macros. Also, shape's built-in derivation rules are initialized.

       Reading the Description File

       After that, all macro definitions made on the command line are made effective. Shape  then
       locates and opens its description file. If no description file is specified as argument to
       the -f option, shape tries to find one of the files  Shapefile,  shapefile,  Makefile,  or
       makefile.   For  each of these names, shape tries to find a regular file first, and, if no
       such file exists, to find the most recent version  of  that  file  in  a  version  control
       archive. If no such version can be found, shape tries the next name.

       When  shape  reads the description file, it collects all macro definitions, and makes them
       immediately effective, unless a macro of the same name has been  defined  on  the  command
       line.  If  the  special  macro IMPORT is encountered, the listed environment variables are
       defined as macros. If macros with the same name as an imported environment variable occurs
       in  the  description  file,  it  has  precedence over the definition from the environment,
       unless the -e switch is in effect.

       When shape reads an include directive, it  evaluates  the  rest  of  the  line  (i.e.  the
       characters that immediately follow the directive), and interprets each word as the name of
       a file to be read. Each of the file names is bound to either a regular file, or  the  most
       recent  version  of the file. Shape opens each of the included files, suspends reading the
       current description file, and continues to read the  contents  of  the  included  file(s),
       before  it  resumes  reading  of  the  original  control  file. If multiple file names are
       specified in an include directive, shape reads each of the files in  turn,  starting  with
       the  leftmost,  and  ending with the rightmost file name. If an included file could not be
       opened, shape issues a warning.

       While shape reads its description files, version selection rules,  and  target  rules  are
       collected.  They  are  defined only after shape has finished reading the description file.
       Macro-, variant-, and variant class definitions are made effective as soon  as  they  have
       been recognized.

       The Build Process

       After  the  description  file  has  been  read,  shape  determines which targets have been
       requested. If targets have been requested from the command line,  shape  will  attempt  to
       build  each  of  them,  starting  with  the  leftmost  target  and  proceeding towards the
       rightmost. If no target has been requested from  the  command  line,  shape  searches  the
       description  file  for a target named .DEFAULT. If such a target exists, and there are any
       dependencies associated with it, shape will attempt to build each of  these  dependencies,
       from  left  to right. If no .DEFAULT target rule has been defined in the description file,
       shape will attempt to build the first target defined in the description file.

       When shape builds a target, it proceeds as follows:

       1)
          determine the names of the  source  objects  for  a  given  target  by  traversing  the
          dependency  graph,  using built-in and user supplied target rules. The dependency graph
          is traversed depth first. The ids of all applied rules are recorded.

       2)
          for each required source object, locate the source version archive in  the  repository.
          Locating of source version archives takes the current vpath into account.

       3)
          bind  each  of  the  source  object's names to an appropriate version as implied by the
          currently active version selection rule. Record the id of each bound dependency.  If  a
          dependency is itself a derived object, use its cache key as id.

       4)
          construct  the  derivation  key  for  the  current  target from the target name and the
          records resulting from steps 1) and 3).

       5)
          search the derived object cache for an object that has a derivation  key  identical  to
          the key constructed in step 4).

       6a)
          if  an  appropriate  derived  object  was found, a copy of it is installed in the build
          directory, rather than deriving it from its sources.

       6b)
          if no appropriate derived object was found, it is  created  by  deriving  it  from  its
          parts.  The  resulting  derived  object  is  put  into  the  derived  object cache, and
          associated with the derivation key resulting from step 4).

       Targets with an empty list of dependencies - and thus an empty derivation key - are always
       (re-) derived.

       When  shape  determines  the  dependencies of a requested target, it does so by evaluating
       either explicit target rules, or by applying - possibly  built-in  -  implicit  rules.  If
       explicit  target  rules  specify  object dependencies but no derivation script in the rule
       body, shape will  attempt  to  supply  an  appropriate  default  derivation  script.  When
       searching for such a default derivation script, shape tries to find an applicable implicit
       rule for the current target. An implicit rule is considered  applicable,  if  it  has  the
       current  target  in  its list of targets (after pattern substitution), and all - explicit,
       and implied - dependencies exist. If no implicit rule is found  to  be  applicable,  shape
       looks  for  the  .DEFAULT  target rule. If such a rule exists, and if it has an associated
       derivation script in its rule body, this script will be  supplied  as  default  derivation
       script.  If  neither  of the two possibilities leads to a default derivation script, shape
       gives up.

       Derived Object Caching

       Before the derivation process for a requested target is started, it is attempted to find a
       suitable  derived object in the derived object cache that matches the required properties.
       Shape is based on the derivation key concept for target objects.  The  derivation  key  is
       constructed  according  to the algorithm described above. Relevant parameters that go into
       the derivation key are the list of dependency  ids,  the  target  rule  id,  the  list  of
       production ingredients, the build platform (usually defined by the macro HOSTTYPE; if this
       macro is not defined, shape takes the host  id  as  build  platform),  and  the  attribute
       expansion  status  of each source object. When an object has been derived, shape stores it
       in the derived object cache, and marks it  with  the  derivation  key  attribute.   For  a
       detailed  trace  of shape's derived object cache handling, and the use of derivation keys,
       run shape with the -D switch.

       Command Execution

       When a target needs to be (re-) derived, shape executes the commands associated  with  the
       target. Before the commands are executed, shape sets up the command execution context. The
       version objects of the target's dependencies are installed as regular files  in  the  file
       system.  If necessary, shape retrieves source objects from the version control archive. If
       a file with the object's name already exists in  the  place  where  a  version  is  to  be
       installed,  shape  will  temporarily  move  it to the AtFS subdirectory. After the command
       script has completed, shape will restore the original state of all affected directories.

       Shape executes a command line by starting the program referenced in  the  $(SHELL)  macro,
       and opening a pipe to the resulting process.  The command line is written to the pipe, and
       thus sent to the $(SHELL) process' standard input.

       Each of the command lines in a rule body are executed by a  separate  process.  Thus,  the
       execution  status  of  separate commands is not preserved. If multiple commands are needed
       that rely on the execution status of previous commands, all these commands must occur in a
       single  command line. This is possible with line continuations (see section on Syntactical
       Structure, above).
       NOTE: many command interpreters use the ``$'' character as special  symbol  (typically  as
       variable  reference).  Make  sure  to  pass  ``$''  characters in commands to the $(SHELL)
       process by using the ``$$'' special macro (see section on Macro References, above).

INCOMPATIBILITIES

       In order to facilitate migration from make(1), shape was designed to be upward  compatible
       with  Makefiles.  Although  most of make's description file features are present in shape,
       there is a number of incompatibilities that may need to be taken  care  of.  There  exists
       also  a  number  of popular extensions of the original make program (e.g. Sun's Make, HP's
       Make, GNU Make, nmake etc.) that offer various special features that aren't  supported  by
       other  make  extensions,  or  by shape. When a migration from make to shape is planned, it
       should be checked whether special extensions or incompatible features are used.

       Features not supported by shape

       Double colon rules
              Double colon rules associate the same target  with  different  derivation  scripts.
              This type of rule is useful to support different derivations for a target depending
              on which dependencies are out of date. Because shape bases its decision whether  to
              derive  on  the derivation key, rather than mere modification time stamps of files,
              this sort of rule makes no sense in shape.

       Archive member targets
              Archive member targets are objects that live in an archive file (see ar(1))  rather
              than  the  file  system.  Within  these  archives,  make bases its decisions on the
              modification time stamps of source files, and archive entry dates. There is no  way
              for  shape  to  simulate  the  concept  of  derivation  keys  for  archive members.
              Maintenance of archives, however, is easy with shape, because all data for compiled
              object files is maintained in the derived object cache. If the source for an object
              that is stored in an archive is modified,  shape  can  rederive  this  object,  and
              selectively replace the entry in the archive.

       SCCS stuff
              In  order  to  provide  basic support for team oriented development processes, make
              allows to retrieve the most recent version of  source  files  from  SCCS  archives.
              Because  of  the  awkward naming convention for SCCS version archive files, special
              support for dealing with these archives had to be built into make. Because shape is
              tightly  integrated  with  the AtFS version object repository, there is no need for
              any special SCCS support.

       Special targets
              Shape does not recognize  the  special  targets  .PRECIOUS:,  and  .SUFFIXES:.  The
              .PRECIOUS  target  in  Makefiles has the purpose to prevent deletion of expensively
              derived intermediate targets  (by  default,  make  deletes  intermediate  targets).
              Because  shape stores intermediate targets in the derived object cache, there is no
              need for the .PRECIOUS feature. To  prevent  caching  of  possibly  large,  useless
              intermediate  targets,  use  the  .NOBPOOL:  special target (see section on Special
              Targets, above). The .SUFFIXES target in Makefiles has the purpose to introduce new
              suffix  types  into  make's  derivation engine, and to determine the order in which
              implicit rules (suffix rules in make terminology) are applied. In shape, new suffix
              types can be added dynamically, simply by introducing new implicit rules. Moreover,
              shape has an intelligent algorithm the determines the applicable implicit rule.

       Features with different semantics

       Environment Variables
              Many make programs  import  the  entire  set  of  environment  variables  as  macro
              definitions  into the build process. This can sometimes produce surprising results.
              In shape, environment variables are explicitly imported  with  the  IMPORT  special
              macro.

       ? Macro
              In  make's target rules, the special macro reference $? is substituted by the names
              of those dependency file names that have been updated since the current target  has
              been  derived. Because shape bases its decision whether to derive on the concept of
              derivation key, rather than mere file modification time stamps, the ?  macro cannot
              be  correctly  defined.  Instead,  shape  substitutes the entire list of dependency
              names - updated or not.

FILES

       Shapefile, shapefile, Makefile, makefile, /tmp/shapeXXXXXX, <target name>.bct

SEE ALSO

       make(1), save(1), retrv(1), vadm(1), vl(1), vgdb(1), vbind(1), afintro(3), atfstkintro(3),
       sttkintro(3), bindrules(7)

CAVEATS AND BUGS

       Macro  references containing string substitutions cause a syntax error if used in place of
       target dependencies. Workaround: use indirect macro substitution.

       There are probably more bugs in shape. Please report any bug findings  to  shape-cr@cs.tu-
       berlin.de.

FURTHER READING

       Axel Mahler:
                 ``Using  the  Shape Toolkit for Cooperative Software Development - A Tutorial'',
                 in the toolkit distribution.

       Axel Mahler and Andreas Lampen:
                 ``An Integrated  Toolset  for  Engineering  Software  Configurations'',  Sigplan
                 Notices,  Vol.  24,  No.  2,  or  Software  Engineering  Notes, Vol.  13, No. 5,
                 November 1988.

       Andreas Lampen and Axel Mahler:
                 ``An Object Base for Attributed Software Objects'', Proceedings of the Fall 1988
                 EUUG Conference.

       These  and  other  papers  are  available  via  anonymous  ftp  from  coma.cs.tu-berlin.de
       (pub/shapeTools/papers).

AUTHOR

       Shape was designed by the shape project team at Technical University Berlin.  The  program
       was originally implemented by Wolfgang Obst (1988). Extensive fixes and modifications were
       introduced by Axel Mahler (1992). Valuable contributions came from Steve Emmerson. In 1993
       most  parts  of  shape  were  re-implemented  by  Axel Mahler. The version binding was re-
       implemented by Andreas Lampen. A complete re-implementation of the  Shapefile  parser  was
       done by Juergen Nickelsen.

       Contact:
       SHAPE
       Technical University Berlin
       Sekr. FR 5-6
       Franklinstr. 28/29
       10587 Berlin

       General correspondence: shape@cs.tu-berlin.de
       Bug reports and modification requests: shape-cr@cs.tu-berlin.de