make - GNU make utility to maintain groups of programs
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
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
Once a suitable makefile exists, each time you change some source files, this
simple shell command:
suffices to perform all necessary recompilations. The make
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.
executes commands in the makefile
to update one or more
, where name
is typically a program. If no -f
option is present, make
will look for the makefiles GNUmakefile
, and Makefile
, in that order.
Normally you should call your makefile either 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
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.
- -b, -m
- These options are ignored for compatibility with other versions of
- -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.
- 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
- 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
- -e, --environment-overrides
- Give variables taken from the environment precedence over variables from
- -f file, --file=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.
- -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
- -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,
- 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
- -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
- -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.
- 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.
- Turn off -w, even if it was turned on implicitly.
- -W file, --what-if=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
- Warn when an undefined variable is referenced.
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
The full documentation for make
is maintained as a Texinfo manual. If the
programs are properly installed at your site, the
- info make
should give you access to the complete manual.
See the chapter ``Problems and Bugs'' in The GNU Make Manual
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 © 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
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/