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MAKE
!!!MAKE
NAME
SYNOPSIS
WARNING
DESCRIPTION
OPTIONS
SEE ALSO
BUGS
AUTHOR
----
!!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
documentation, refer to the Info file __make.info__ which
is made from the [TexInfo|texinfo(5)] 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. The
manual describes the GNU implementation of ''make'',
which was written by RichardStallman 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: __-I__''dir'' 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.


__-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


''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 StanfordUniversity.
It has been reworked by Roland
!McGrath.
----
[CategorySoftwareEngineeringTools]
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Last edited on Friday, January 9, 2004 5:13:57 am by StuartYeates
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