The make 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 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
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:
suffices to perform all necessary recompilations. The make program
uses 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.
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
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.
These options are ignored for compatibility with other versions
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.
-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.
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 flags.
Give variables taken from the environment precedence over
variables from makefiles.
-f file, --file=file, --makefile=FILE
Use file as a makefile.
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.
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
-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
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, --assume-old=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.
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.
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.
``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.
Eliminate use of the built-in implicit rules. Also clear out
the default list of suffixes for suffix rules.
Don't define any built-in variables.
-s, --silent, --quiet
Silent operation; do not print the commands as they are
-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
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
Information about the disposition of each target is printed (why
the target is being rebuilt and what commands are run to rebuild
Print the version of the make program plus a copyright, a list
of authors and a notice that there is no warranty.
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, --new-file=file, --assume-new=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.
Warn when an undefined variable is referenced.
GNU make 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 encountered.
The full documentation for make is maintained as a Texinfo manual.
If the info and make programs are properly installed at your site,
should give you access to the complete manual.
This page is part of the make (GNU make) project. Information about
the project can be found at ⟨http://www.gnu.org/software/make/⟩. If
you have a bug report for this manual page, see
⟨http://www.gnu.org/software/make/⟩. This page was obtained from the
tarball make-4.2.tar.gz fetched from ⟨http://ftp.gnu.org/gnu/make/⟩
on 2016-12-10. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-to-
date source for the page, or you have corrections or improvements to
the information in this COLOPHON (which is not part of the original
manual page), send a mail to email@example.com
GNU 28 February 2016 MAKE(1)