Provided by: make_4.2.1-1.2_amd64 bug

NAME

       make - GNU make utility to maintain groups of programs

SYNOPSIS

       make [OPTION]... [TARGET]...

DESCRIPTION

       The  make  utility will determine automatically which pieces of a large program need to be
       recompiled, and issue the commands to  recompile  them.   The  manual  describes  the  GNU
       implementation  of  make, which was written by Richard Stallman and Roland McGrath, and is
       currently maintained by Paul Smith.  Our examples show C programs,  since  they  are  very
       common,  but you can use make with any programming language whose compiler can be run with
       a shell command.  In fact, make is not limited to programs.  You can use  it  to  describe
       any  task  where  some files must be updated automatically from others whenever the others
       change.

       To prepare to use make, you must write a file  called  the  makefile  that  describes  the
       relationships  among  files in your program, and the states the commands for updating each
       file.  In a program, typically the executable file is updated from object files, which are
       in turn made by compiling source files.

       Once a suitable makefile exists, each time you change some source files, this simple shell
       command:

              make

       suffices to perform all necessary recompilations.  The  make  program  uses  the  makefile
       description and the last-modification times of the files to decide which of the files need
       to be updated.  For each of those files, it issues the commands recorded in the makefile.

       make executes commands in the makefile to update one or more target names, where  name  is
       typically  a  program.   If  no  -f  option  is  present, make will look for the makefiles
       GNUmakefile, makefile, and Makefile, in that order.

       Normally you should call  your  makefile  either  makefile  or  Makefile.   (We  recommend
       Makefile  because  it appears prominently near the beginning of a directory listing, right
       near other important files such as README.)  The first name checked, GNUmakefile,  is  not
       recommended  for  most makefiles.  You should use this name if you have a makefile that is
       specific to GNU make, and will not be understood by other versions of make.   If  makefile
       is '-', the standard input is read.

       make  updates  a  target if it depends on prerequisite files that have been modified since
       the target was last modified, or if the target does not exist.

OPTIONS

       -b, -m
            These options are ignored for compatibility with other versions of make.

       -B, --always-make
            Unconditionally make all targets.

       -C dir, --directory=dir
            Change to directory dir before reading the makefiles  or  doing  anything  else.   If
            multiple  -C options are specified, each is interpreted relative to the previous one:
            -C / -C etc is equivalent  to  -C  /etc.   This  is  typically  used  with  recursive
            invocations of make.

       -d   Print  debugging  information  in  addition  to  normal  processing.   The  debugging
            information says which files are being considered for remaking, which file-times  are
            being  compared  and with what results, which files actually need to be remade, which
            implicit rules are considered and which are  applied---everything  interesting  about
            how make decides what to do.

       --debug[=FLAGS]
            Print  debugging  information  in  addition  to  normal processing.  If the FLAGS are
            omitted, then the behavior is the same as if -d was specified.  FLAGS may  be  a  for
            all  debugging  output  (same as using -d), b for basic debugging, v for more verbose
            basic debugging, i for showing  implicit  rules,  j  for  details  on  invocation  of
            commands,  and  m  for  debugging  while  remaking  makefiles.   Use n to disable all
            previous debugging flags.

       -e, --environment-overrides
            Give variables taken from the environment precedence over variables from makefiles.

       -f file, --file=file, --makefile=FILE
            Use file as a makefile.

       -i, --ignore-errors
            Ignore all errors in commands executed to remake files.

       -I dir, --include-dir=dir
            Specifies a directory dir to search for included makefiles.  If  several  -I  options
            are  used  to  specify several directories, the directories are searched in the order
            specified.  Unlike the arguments to other flags of make, directories  given  with  -I
            flags  may  come  directly after the flag: -Idir is allowed, as well as -I dir.  This
            syntax is allowed for compatibility with the C preprocessor's -I flag.

       -j [jobs], --jobs[=jobs]
            Specifies the number of jobs (commands) to run simultaneously.  If there is more than
            one  -j  option,  the  last  one  is effective.  If the -j option is given without an
            argument, make will not limit the number of jobs that can  run  simultaneously.  When
            make  invokes  a sub-make, all instances of make will coordinate to run the specified
            number of jobs at a time; see  the  section  PARALLEL  MAKE  AND  THE  JOBSERVER  for
            details.

       --jobserver-fds [R,W]
            Internal  option  make uses to pass the jobserver pipe read and write file descriptor
            numbers to sub-makes; see the section PARALLEL MAKE AND THE JOBSERVER for details

       -k, --keep-going
            Continue as much as possible after an error.  While the target that failed, and those
            that  depend  on it, cannot be remade, the other dependencies of these targets can be
            processed all the same.

       -l [load], --load-average[=load]
            Specifies that no new jobs (commands) should be started  if  there  are  others  jobs
            running  and  the  load  average is at least load (a floating-point number).  With no
            argument, removes a previous load limit.

       -L, --check-symlink-times
            Use the latest mtime between symlinks and target.

       -n, --just-print, --dry-run, --recon
            Print the commands that would be executed, but do not execute them (except in certain
            circumstances).

       -o file, --old-file=file, --assume-old=file
            Do  not  remake  the  file file even if it is older than its dependencies, and do not
            remake anything on account of changes in file.  Essentially the file  is  treated  as
            very old and its rules are ignored.

       -O[type], --output-sync[=type]
            When  running  multiple  jobs  in  parallel with -j, ensure the output of each job is
            collected together rather than interspersed with output from other jobs.  If type  is
            not  specified  or  is  target  the  output from the entire recipe for each target is
            grouped together.  If type is line the output from each command line within a  recipe
            is  grouped  together.   If  type  is recurse output from an entire recursive make is
            grouped together.  If type is none output synchronization is disabled.

       -p, --print-data-base
            Print the data base (rules  and  variable  values)  that  results  from  reading  the
            makefiles;  then  execute  as  usual or as otherwise specified.  This also prints the
            version information given by the -v switch (see  below).   To  print  the  data  base
            without trying to remake any files, use make -p -f/dev/null.

       -q, --question
            ``Question  mode''.   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,  nonzero
            otherwise.

       -r, --no-builtin-rules
            Eliminate  use  of  the  built-in implicit rules.  Also clear out the default list of
            suffixes for suffix rules.

       -R, --no-builtin-variables
            Don't define any built-in variables.

       -s, --silent, --quiet
            Silent operation; do not print the commands as they are executed.

       -S, --no-keep-going, --stop
            Cancel the effect of the -k option.  This is never necessary except  in  a  recursive
            make  where -k might be inherited from the top-level make via MAKEFLAGS or if you set
            -k in MAKEFLAGS in your environment.

       -t, --touch
            Touch files (mark them up to date without really changing them)  instead  of  running
            their  commands.   This  is  used to pretend that the commands were done, in order to
            fool future invocations of make.

       --trace
            Information about the disposition of each target is printed (why the target is  being
            rebuilt and what commands are run to rebuild it).

       -v, --version
            Print  the  version  of  the  make  program plus a copyright, a list of authors and a
            notice that there is no warranty.

       -w, --print-directory
            Print a message containing the working directory before and after  other  processing.
            This  may be useful for tracking down errors from complicated nests of recursive make
            commands.

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

       -W file, --what-if=file, --new-file=file, --assume-new=file
            Pretend that the target file has just been modified.  When used  with  the  -n  flag,
            this  shows you what would happen if you were to modify that file.  Without -n, it is
            almost the same as running a touch command on the given  file  before  running  make,
            except that the modification time is changed only in the imagination of make.

       --warn-undefined-variables
            Warn when an undefined variable is referenced.

EXIT STATUS

       GNU  make  exits  with  a  status of zero if all makefiles were successfully parsed and no
       targets that were built failed.  A status of one will be returned if the -q flag was  used
       and  make  determines that a target needs to be rebuilt.  A status of two will be returned
       if any errors were encountered.

SEE ALSO

       The full documentation for make is maintained as a Texinfo manual.  If the info  and  make
       programs are properly installed at your site, the command

              info make

       should give you access to the complete manual.

PARALLEL MAKE AND THE JOBSERVER

       Using  the  -j  option,  the  user  can  instruct  make  to  execute tasks in parallel. By
       specifying a numeric argument to -j the user may specify an upper limit of the  number  of
       parallel tasks to be run.

       When  the build environment is such that a top level make invokes sub-makes (for instance,
       a style in which each sub-directory contains its own Makefile ), no individual instance of
       make  knows  how  many tasks are running in parallel, so keeping the number of tasks under
       the upper limit would be impossible without communication between all the  make  instances
       running.  While solutions like having the top level make serve as a central controller are
       feasible, or using other synchronization mechanisms like shared memory or sockets  can  be
       created, the current implementation uses a simple shared pipe.

       This  pipe  is  created by the top-level make process, and passed on to all the sub-makes.
       The top level makeprocesswrites N-1 one-byte tokens into the pipe (The top level  make  is
       assumed  to  reserve  one token for itself). Whenever any of the make processes (including
       the top-level make ) needs to run a new task, it reads a byte from  the  shared  pipe.  If
       there  are  no  tokens left, it must wait for a token to be written back to the pipe. Once
       the task is completed, the make process writes a token back to the pipe (and thus, if  the
       tokens  had  been  exhausted, unblocking the first make process that was waiting to read a
       token).  Since only N-1 tokens were written into the pipe, no more than  N  tasks  can  be
       running at any given time.

       If  the  job  to  be  run  is  not a sub-make then make will close the jobserver pipe file
       descriptors before invoking the commands, so that the command can not interfere  with  the
       jobserver, and the command does not find any unusual file descriptors.

BUGS

       See the chapter ``Problems and Bugs'' in The GNU Make Manual.

AUTHOR

       This  manual  page  contributed  by  Dennis Morse of Stanford University.  Further updates
       contributed by Mike Frysinger.  It has been reworked by  Roland  McGrath.   Maintained  by
       Paul Smith.

COPYRIGHT

       Copyright  © 1992-1993, 1996-2016 Free Software Foundation, Inc.  This file is part of GNU
       make.

       GNU Make is free software; you can redistribute it and/or modify it under the terms of the
       GNU  General Public License as published by the Free Software Foundation; either version 3
       of the License, or (at your option) any later version.

       GNU Make is distributed in the hope that it will be  useful,  but  WITHOUT  ANY  WARRANTY;
       without  even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
       See the GNU General Public License for more details.

       You should have received a copy of the GNU General Public License along with this program.
       If not, see http://www.gnu.org/licenses/.