MAKE(1) GNU MAKE(1)
LOCAL USER COMMANDS LOCAL USER COMMANDS
22 August 1989
NAME
gmake - GNU make utility to maintain groups of programs
SYNOPSIS
gmake [ -f makefile ] [ options ] ... [ targets ] ...
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.texi.
DESCRIPTION
The purpose of the gmake 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, and is currently maintained by Paul Smith. Our
examples show C programs, since they are most common, but you can use
gmake with any programming language whose compiler can be run with a
shell command. In fact, gmake 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 gmake, 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:
gmake
suffices to perform all necessary recompilations. The gmake 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. gmake
executes commands in the makefile to update one or more target names,
where name is typically a program. If no -f option is present, gmake
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. gmake 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.
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OPTIONS
-b, -m
These options are ignored for compatibility with other versions
of make.
-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 gmake.
-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 gmake decides what to do.
--debug[=FLAGS]
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.
-e, --environment-overrides
Give variables taken from the environment precedence over
variables from makefiles.
+-f file, --file=file, --makefile=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 gmake, 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.
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-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, gmake 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 limit.
-L, --check-symlink-times
Use the latest mtime between symlinks and target.
-n, --just-print, --dry-run,
Print the commands that would be executed, but do not execute
them.
-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.
-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 gmake -p -f/dev/null.
-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.
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-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 gmake where -k might be inherited from the
top-level gmake 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
gmake.
-v, --version
Print the version of the gmake 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 gmake commands.
--no-print-directory
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 gmake, except that
the modification time is changed only in the imagination of
gmake.
--warn-undefined-variables
Warn when an undefined variable is referenced.
EXIT STATUS
GNU gmake 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 gmake determines
that a target needs to be rebuilt. A status of two will be returned
if any errors were encountered.
SEE ALSO
The GNU Make Manual
BUGS
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MAKE(1) GNU MAKE(1)
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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. Further updates contributed
by Mike Frysinger.
COPYRIGHT
Copyright (C) 1992, 1993, 1996, 1999 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 2, or (at your option) any later version. 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 GNU make; see the file COPYING. If not,
write to the Free Software Foundation, Inc., 51 Franklin St, Fifth
Floor, Boston, MA 02110-1301, USA.
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