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 Info file make or the DVI file
make.dvi which are 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. 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.
-e Give variables taken from the environment precedence
over variables 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 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.