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       make - GNU make utility to maintain groups of programs

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

       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
       which is	made from the Texinfo source file make.texinfo.

       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:


       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.


       -m   These options are ignored for compatibility	with other versions of

       -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

       -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  re-
	    sults,  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 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

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

       -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 ig-

       -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 re-
	    make 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 ex-
	    cept 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 en-

       -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

       -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.

       The GNU Make Manual

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

       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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