.TH MAKE 1 "28 February 2016" "GNU" "User Commands"

.SH NAME

make \- GNU make utility to maintain groups of programs

.SH SYNOPSIS

.B make

[\fIOPTION\fR]... [\fITARGET\fR]...

.SH DESCRIPTION

.LP

The

.I 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

.BR 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

.B make

with any programming language whose compiler can be run with a shell command.

In fact,

.B 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.

.LP

To prepare to use

.BR make ,

you must write a file called the

.I 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.

.LP

Once a suitable makefile exists, each time you change some source files,

this simple shell command:

.sp 1

.RS

.B make

.RE

.sp 1

suffices to perform all necessary recompilations.

The

.B 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.

.LP

.B make

executes commands in the

.I makefile

to update one or more target

.IR names ,

where

.I name

is typically a program.

If no

.B \-f

option is present,

.B make

will look for the makefiles

.IR GNUmakefile ,

.IR makefile ,

and

.IR Makefile ,

in that order.

.LP

Normally you should call your makefile either

.I makefile

or

.IR Makefile .

(We recommend

.I Makefile

because it appears prominently near the beginning of a directory

listing, right near other important files such as

.IR  README .)

The first name checked,

.IR GNUmakefile ,

is not recommended for most makefiles.  You should use this name if you have a

makefile that is specific to GNU

.BR make ,

and will not be understood by other versions of

.BR make .

If

.I makefile

is '\-', the standard input is read.

.LP

.B 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.

.SH OPTIONS

.sp 1

.TP 0.5i

\fB\-b\fR, \fB\-m\fR

These options are ignored for compatibility with other versions of

.BR make .

.TP 0.5i

\fB\-B\fR, \fB\-\-always\-make\fR

Unconditionally make all targets.

.TP 0.5i

\fB\-C\fR \fIdir\fR, \fB\-\-directory\fR=\fIdir\fR

Change to directory

.I dir

before reading the makefiles or doing anything else.

If multiple

.B \-C

options are specified, each is interpreted relative to the

previous one:

.BR "\-C " /

.BR "\-C " etc

is equivalent to

.BR "\-C " /etc.

This is typically used with recursive invocations of

.BR make .

.TP 0.5i

.B \-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

.B make

decides what to do.

.TP 0.5i

.BI \-\-debug "[=FLAGS]"

Print debugging information in addition to normal processing.

If the

.I FLAGS

are omitted, then the behavior is the same as if

.B \-d

was specified.

.I FLAGS

may be

.I a

for all debugging output (same as using

.BR \-d ),

.I b

for basic debugging,

.I v

for more verbose basic debugging,

.I i

for showing implicit rules,

.I j

for details on invocation of commands, and

.I m

for debugging while remaking makefiles.  Use

.I n

to disable all previous debugging flags.

.TP 0.5i

\fB\-e\fR, \fB\-\-environment\-overrides\fR

Give variables taken from the environment precedence

over variables from makefiles.

.TP 0.5i

\fB\-f\fR \fIfile\fR, \fB\-\-file\fR=\fIfile\fR, \fB\-\-makefile\fR=\fIFILE\fR

Use

.I file

as a makefile.

.TP 0.5i

\fB\-i\fR, \fB\-\-ignore\-errors\fR

Ignore all errors in commands executed to remake files.

.TP 0.5i

\fB\-I\fR \fIdir\fR, \fB\-\-include\-dir\fR=\fIdir\fR

Specifies a directory

.I dir

to search for included makefiles.

If several

.B \-I

options are used to specify several directories, the directories are

searched in the order specified.

Unlike the arguments to other flags of

.BR make ,

directories given with

.B \-I

flags may come directly after the flag:

.BI \-I dir

is allowed, as well as

.B \-I

.IR dir .

This syntax is allowed for compatibility with the C

preprocessor's

.B \-I

flag.

.TP 0.5i

\fB\-j\fR [\fIjobs\fR], \fB\-\-jobs\fR[=\fIjobs\fR]

Specifies the number of

.I jobs

(commands) to run simultaneously.

If there is more than one

.B \-j

option, the last one is effective.

If the

.B \-j

option is given without an argument,

.BR make

will not limit the number of jobs that can run simultaneously.

.TP 0.5i

\fB\-k\fR, \fB\-\-keep\-going\fR

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.

.TP 0.5i

\fB\-l\fR [\fIload\fR], \fB\-\-load\-average\fR[=\fIload\fR]

Specifies that no new jobs (commands) should be started if there are

others jobs running and the load average is at least

.I load

(a floating-point number).

With no argument, removes a previous load limit.

.TP 0.5i

\fB\-L\fR, \fB\-\-check\-symlink\-times\fR

Use the latest mtime between symlinks and target.

.TP 0.5i

\fB\-n\fR, \fB\-\-just\-print\fR, \fB\-\-dry\-run\fR, \fB\-\-recon\fR

Print the commands that would be executed, but do not execute them (except in

certain circumstances).

.TP 0.5i

\fB\-o\fR \fIfile\fR, \fB\-\-old\-file\fR=\fIfile\fR, \fB\-\-assume\-old\fR=\fIfile\fR

Do not remake the file

.I file

even if it is older than its dependencies, and do not remake anything

on account of changes in

.IR file .

Essentially the file is treated as very old and its rules are ignored.

.TP 0.5i

\fB\-O\fR[\fItype\fR], \fB\-\-output\-sync\fR[=\fItype\fR]

When running multiple jobs in parallel with \fB-j\fR, ensure the output of

each job is collected together rather than interspersed with output from

other jobs.  If

.I type

is not specified or is

.B target

the output from the entire recipe for each target is grouped together.  If

.I type

is

.B line

the output from each command line within a recipe is grouped together.

If

.I type

is

.B recurse

output from an entire recursive make is grouped together.  If

.I type

is

.B none

output synchronization is disabled.

.TP 0.5i

\fB\-p\fR, \fB\-\-print\-data\-base\fR

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

.B \-v

switch (see below).

To print the data base without trying to remake any files, use

.IR "make \-p \-f/dev/null" .

.TP 0.5i

\fB\-q\fR, \fB\-\-question\fR

``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.

.TP 0.5i

\fB\-r\fR, \fB\-\-no\-builtin\-rules\fR

Eliminate use of the built\-in implicit rules.

Also clear out the default list of suffixes for suffix rules.

.TP 0.5i

\fB\-R\fR, \fB\-\-no\-builtin\-variables\fR

Don't define any built\-in variables.

.TP 0.5i

\fB\-s\fR, \fB\-\-silent\fR, \fB\-\-quiet\fR

Silent operation; do not print the commands as they are executed.

.TP 0.5i

\fB\-S\fR, \fB\-\-no\-keep\-going\fR, \fB\-\-stop\fR

Cancel the effect of the

.B \-k

option.

This is never necessary except in a recursive

.B make

where

.B \-k

might be inherited from the top-level

.B make

via MAKEFLAGS or if you set

.B \-k

in MAKEFLAGS in your environment.

.TP 0.5i

\fB\-t\fR, \fB\-\-touch\fR

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

.BR make .

.TP 0.5i

.B \-\-trace

Information about the disposition of each target is printed (why the target is

being rebuilt and what commands are run to rebuild it).

.TP 0.5i

\fB\-v\fR, \fB\-\-version\fR

Print the version of the

.B make

program plus a copyright, a list of authors and a notice that there

is no warranty.

.TP 0.5i

\fB\-w\fR, \fB\-\-print\-directory\fR

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

.B make

commands.

.TP 0.5i

.B \-\-no\-print\-directory

Turn off

.BR \-w ,

even if it was turned on implicitly.

.TP 0.5i

\fB\-W\fR \fIfile\fR, \fB\-\-what\-if\fR=\fIfile\fR, \fB\-\-new\-file\fR=\fIfile\fR, \fB\-\-assume\-new\fR=\fIfile\fR

Pretend that the target

.I file

has just been modified.

When used with the

.B \-n

flag, this shows you what would happen if you were to modify that file.

Without

.BR \-n ,

it is almost the same as running a

.I touch

command on the given file before running

.BR make ,

except that the modification time is changed only in the imagination of

.BR make .

.TP 0.5i

.B \-\-warn\-undefined\-variables

Warn when an undefined variable is referenced.

.SH "EXIT STATUS"

GNU

.B 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

.B \-q

flag was used and

.B make

determines that a target needs to be rebuilt.  A status of two will be

returned if any errors were encountered.

.SH "SEE ALSO"

The full documentation for

.B make

is maintained as a Texinfo manual.  If the

.B info

and

.B make

programs are properly installed at your site, the command

.IP

.B info make

.PP

should give you access to the complete manual.

.SH BUGS

See the chapter ``Problems and Bugs'' in

.IR "The GNU Make Manual" .

.SH AUTHOR

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.

.SH "COPYRIGHT"

Copyright \(co 1992-1993, 1996-2016 Free Software Foundation, Inc.

This file is part of

.IR "GNU make" .

.LP

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

version.

.LP

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.

.LP

You should have received a copy of the GNU General Public License along with

this program.  If not, see

.IR http://www.gnu.org/licenses/ .