make





NAME

      make - GNU make utility to maintain groups of programs


SYNOPSIS

      make [ -f makefile ] [ option ] ...  target ...


WARNING

      This man paage is an extract of the documentation of GNU make . It is
      updated only occasionally, because the GNU project does not use nroff.
      For complete, current documentation, refer to the document "GNU Make
      User's Manual", 3BSE001520.


DESCRIPTION

      The purpose of the make utility is to determine automatically which
      pieces of a large program need to be recompiled, and issue the
      commands to recompile them.  This manual describes the GNU
      implementation of make, which was written by Richard Stallman and
      Roland McGrath.  Our examples show C programs, since they are most
      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 data base 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 data base.  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.

      -C 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.

      -f file
           Use file as a makefile.

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

      -I 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
           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.

      -k   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

      -l 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.

      -n   Print the commands that would be executed, but do not execute
           them.

      -o 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.

      -p   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 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   Eliminate use of the built-in implicit rules.  Also clear out the
           default list of suffixes for suffix rules.

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

      -S   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 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.

      -v   Print the version of the make program plus a copyright, a list of
           authors and a notice that there is no warranty.  After this
           information is printed, processing continues normally.  To get
           this information without doing anything else, use make -v
           -f/dev/null.

      -w   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.

      -W 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.


SEE ALSO

      /usr/local/doc/gnumake.dvi
                          The GNU Make Manual


BUGS

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


AUTHOR

      This manual page contributed by Dennis Morse of Stanford University.
      It has been reworked by Roland McGrath.