make



MAKE(1L)                      LOCAL USER COMMANDS                     MAKE(1L)




NAME

       make - GNU make utility to maintain groups of programs


SYNOPSIS

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


WARNING

       This  man  page 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 Info file make.info
       which is made from the Texinfo source file make.texinfo.


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.  The 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  exe-
       cutable  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  begin-
       ning  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 any-
            thing  else.  If multiple -C options are specified, each is inter-
            preted 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  interest-
            ing about how make decides what to do.

       -e   Give  variables  taken  from the environment precedence over vari-
            ables from makefiles.

       -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 argu-
            ments  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 dependen-
            cies,  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 spec-
            ified.   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.

       -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

       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.



GNU                             22 August 1989                        MAKE(1L)

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