MAKE(1L) LOCAL USER COMMANDS MAKE(1L)NAME
make - GNU make utility to maintain groups of programs
SYNOPSIS
make [ -f makefile ] [ option ] ... target ...
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 docu-
mentation, refer to the Info file make.info which is made
from the Texinfo source file make.texinfo.
DESCRIPTION
The purpose of the make utility is to determine automati-
cally which pieces of a large program need to be recom-
piled, and issue the commands to recompile them. The man-
ual describes the GNU implementation of make, which was
written by Richard Stallman and Roland McGrath. Our exam-
ples 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 com-
piling 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-mod-
ification 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 modi-
fied, 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 previ-
ous 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---every-
thing 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 compati-
bility with the C preprocessor's -I flag.
-j jobs
Specifies the number of jobs (commands) to run simul-
taneously. 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 copy-
right, 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 use-
ful 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
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.
GNU 22 August 1989 MAKE(1L)
