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1 .TH MAKE 1 "28 February 2016" "GNU" "User Commands"
2 .SH NAME
3 make \- GNU make utility to maintain groups of programs
4 .SH SYNOPSIS
5 .B make
6 [\fIOPTION\fR]... [\fITARGET\fR]...
7 .SH DESCRIPTION
8 .LP
9 The
10 .I make
11 utility will determine automatically which pieces of a large program need to
12 be recompiled, and issue the commands to recompile them. The manual describes
13 the GNU implementation of
14 .BR make ,
15 which was written by Richard Stallman and Roland McGrath, and is currently
16 maintained by Paul Smith. Our examples show C programs, since they are very
17 common, but you can use
18 .B make
19 with any programming language whose compiler can be run with a shell command.
20 In fact,
21 .B make
22 is not limited to programs. You can use it to describe any task where some
23 files must be updated automatically from others whenever the others change.
24 .LP
25 To prepare to use
26 .BR make ,
27 you must write a file called the
28 .I makefile
29 that describes the relationships among files in your program, and the states
30 the commands for updating each file. In a program, typically the executable
31 file is updated from object files, which are in turn made by compiling source
32 files.
33 .LP
34 Once a suitable makefile exists, each time you change some source files,
35 this simple shell command:
36 .sp 1
37 .RS
38 .B make
39 .RE
40 .sp 1
41 suffices to perform all necessary recompilations.
42 The
43 .B make
44 program uses the makefile description and the last-modification times of the
45 files to decide which of the files need to be updated. For each of those
46 files, it issues the commands recorded in the makefile.
47 .LP
48 .B make
49 executes commands in the
50 .I makefile
51 to update one or more target
52 .IR names ,
53 where
54 .I name
55 is typically a program.
56 If no
57 .B \-f
58 option is present,
59 .B make
60 will look for the makefiles
61 .IR GNUmakefile ,
62 .IR makefile ,
63 and
64 .IR Makefile ,
65 in that order.
66 .LP
67 Normally you should call your makefile either
68 .I makefile
69 or
70 .IR Makefile .
71 (We recommend
72 .I Makefile
73 because it appears prominently near the beginning of a directory
74 listing, right near other important files such as
75 .IR README .)
76 The first name checked,
77 .IR GNUmakefile ,
78 is not recommended for most makefiles. You should use this name if you have a
79 makefile that is specific to GNU
80 .BR make ,
81 and will not be understood by other versions of
82 .BR make .
83 If
84 .I makefile
85 is '\-', the standard input is read.
86 .LP
87 .B make
88 updates a target if it depends on prerequisite files
89 that have been modified since the target was last modified,
90 or if the target does not exist.
91 .SH OPTIONS
92 .sp 1
93 .TP 0.5i
94 \fB\-b\fR, \fB\-m\fR
95 These options are ignored for compatibility with other versions of
96 .BR make .
97 .TP 0.5i
98 \fB\-B\fR, \fB\-\-always\-make\fR
99 Unconditionally make all targets.
100 .TP 0.5i
101 \fB\-C\fR \fIdir\fR, \fB\-\-directory\fR=\fIdir\fR
102 Change to directory
103 .I dir
104 before reading the makefiles or doing anything else.
105 If multiple
106 .B \-C
107 options are specified, each is interpreted relative to the
108 previous one:
109 .BR "\-C " /
110 .BR "\-C " etc
111 is equivalent to
112 .BR "\-C " /etc.
113 This is typically used with recursive invocations of
114 .BR make .
115 .TP 0.5i
116 .B \-d
117 Print debugging information in addition to normal processing.
118 The debugging information says which files are being considered for
119 remaking, which file-times are being compared and with what results,
120 which files actually need to be remade, which implicit rules are
121 considered and which are applied---everything interesting about how
122 .B make
123 decides what to do.
124 .TP 0.5i
125 .BI \-\-debug "[=FLAGS]"
126 Print debugging information in addition to normal processing.
127 If the
128 .I FLAGS
129 are omitted, then the behavior is the same as if
130 .B \-d
131 was specified.
132 .I FLAGS
133 may be
134 .I a
135 for all debugging output (same as using
136 .BR \-d ),
137 .I b
138 for basic debugging,
139 .I v
140 for more verbose basic debugging,
141 .I i
142 for showing implicit rules,
143 .I j
144 for details on invocation of commands, and
145 .I m
146 for debugging while remaking makefiles. Use
147 .I n
148 to disable all previous debugging flags.
149 .TP 0.5i
150 \fB\-e\fR, \fB\-\-environment\-overrides\fR
151 Give variables taken from the environment precedence
152 over variables from makefiles.
153 .TP 0.5i
154 \fB\-f\fR \fIfile\fR, \fB\-\-file\fR=\fIfile\fR, \fB\-\-makefile\fR=\fIFILE\fR
155 Use
156 .I file
157 as a makefile.
158 .TP 0.5i
159 \fB\-i\fR, \fB\-\-ignore\-errors\fR
160 Ignore all errors in commands executed to remake files.
161 .TP 0.5i
162 \fB\-I\fR \fIdir\fR, \fB\-\-include\-dir\fR=\fIdir\fR
163 Specifies a directory
164 .I dir
165 to search for included makefiles.
166 If several
167 .B \-I
168 options are used to specify several directories, the directories are
169 searched in the order specified.
170 Unlike the arguments to other flags of
171 .BR make ,
172 directories given with
173 .B \-I
174 flags may come directly after the flag:
175 .BI \-I dir
176 is allowed, as well as
177 .B \-I
178 .IR dir .
179 This syntax is allowed for compatibility with the C
180 preprocessor's
181 .B \-I
182 flag.
183 .TP 0.5i
184 \fB\-j\fR [\fIjobs\fR], \fB\-\-jobs\fR[=\fIjobs\fR]
185 Specifies the number of
186 .I jobs
187 (commands) to run simultaneously.
188 If there is more than one
189 .B \-j
190 option, the last one is effective.
191 If the
192 .B \-j
193 option is given without an argument,
194 .BR make
195 will not limit the number of jobs that can run simultaneously.
196 .TP 0.5i
197 \fB\-k\fR, \fB\-\-keep\-going\fR
198 Continue as much as possible after an error.
199 While the target that failed, and those that depend on it, cannot
200 be remade, the other dependencies of these targets can be processed
201 all the same.
202 .TP 0.5i
203 \fB\-l\fR [\fIload\fR], \fB\-\-load\-average\fR[=\fIload\fR]
204 Specifies that no new jobs (commands) should be started if there are
205 others jobs running and the load average is at least
206 .I load
207 (a floating-point number).
208 With no argument, removes a previous load limit.
209 .TP 0.5i
210 \fB\-L\fR, \fB\-\-check\-symlink\-times\fR
211 Use the latest mtime between symlinks and target.
212 .TP 0.5i
213 \fB\-n\fR, \fB\-\-just\-print\fR, \fB\-\-dry\-run\fR, \fB\-\-recon\fR
214 Print the commands that would be executed, but do not execute them (except in
215 certain circumstances).
216 .TP 0.5i
217 \fB\-o\fR \fIfile\fR, \fB\-\-old\-file\fR=\fIfile\fR, \fB\-\-assume\-old\fR=\fIfile\fR
218 Do not remake the file
219 .I file
220 even if it is older than its dependencies, and do not remake anything
221 on account of changes in
222 .IR file .
223 Essentially the file is treated as very old and its rules are ignored.
224 .TP 0.5i
225 \fB\-O\fR[\fItype\fR], \fB\-\-output\-sync\fR[=\fItype\fR]
226 When running multiple jobs in parallel with \fB-j\fR, ensure the output of
227 each job is collected together rather than interspersed with output from
228 other jobs. If
229 .I type
230 is not specified or is
231 .B target
232 the output from the entire recipe for each target is grouped together. If
233 .I type
234 is
235 .B line
236 the output from each command line within a recipe is grouped together.
237 If
238 .I type
239 is
240 .B recurse
241 output from an entire recursive make is grouped together. If
242 .I type
243 is
244 .B none
245 output synchronization is disabled.
246 .TP 0.5i
247 \fB\-p\fR, \fB\-\-print\-data\-base\fR
248 Print the data base (rules and variable values) that results from
249 reading the makefiles; then execute as usual or as otherwise
250 specified.
251 This also prints the version information given by the
252 .B \-v
253 switch (see below).
254 To print the data base without trying to remake any files, use
255 .IR "make \-p \-f/dev/null" .
256 .TP 0.5i
257 \fB\-q\fR, \fB\-\-question\fR
258 ``Question mode''.
259 Do not run any commands, or print anything; just return an exit status
260 that is zero if the specified targets are already up to date, nonzero
261 otherwise.
262 .TP 0.5i
263 \fB\-r\fR, \fB\-\-no\-builtin\-rules\fR
264 Eliminate use of the built\-in implicit rules.
265 Also clear out the default list of suffixes for suffix rules.
266 .TP 0.5i
267 \fB\-R\fR, \fB\-\-no\-builtin\-variables\fR
268 Don't define any built\-in variables.
269 .TP 0.5i
270 \fB\-s\fR, \fB\-\-silent\fR, \fB\-\-quiet\fR
271 Silent operation; do not print the commands as they are executed.
272 .TP 0.5i
273 \fB\-S\fR, \fB\-\-no\-keep\-going\fR, \fB\-\-stop\fR
274 Cancel the effect of the
275 .B \-k
276 option.
277 This is never necessary except in a recursive
278 .B make
279 where
280 .B \-k
281 might be inherited from the top-level
282 .B make
283 via MAKEFLAGS or if you set
284 .B \-k
285 in MAKEFLAGS in your environment.
286 .TP 0.5i
287 \fB\-t\fR, \fB\-\-touch\fR
288 Touch files (mark them up to date without really changing them)
289 instead of running their commands.
290 This is used to pretend that the commands were done, in order to fool
291 future invocations of
292 .BR make .
293 .TP 0.5i
294 .B \-\-trace
295 Information about the disposition of each target is printed (why the target is
296 being rebuilt and what commands are run to rebuild it).
297 .TP 0.5i
298 \fB\-v\fR, \fB\-\-version\fR
299 Print the version of the
300 .B make
301 program plus a copyright, a list of authors and a notice that there
302 is no warranty.
303 .TP 0.5i
304 \fB\-w\fR, \fB\-\-print\-directory\fR
305 Print a message containing the working directory
306 before and after other processing.
307 This may be useful for tracking down errors from complicated nests of
308 recursive
309 .B make
310 commands.
311 .TP 0.5i
312 .B \-\-no\-print\-directory
313 Turn off
314 .BR \-w ,
315 even if it was turned on implicitly.
316 .TP 0.5i
317 \fB\-W\fR \fIfile\fR, \fB\-\-what\-if\fR=\fIfile\fR, \fB\-\-new\-file\fR=\fIfile\fR, \fB\-\-assume\-new\fR=\fIfile\fR
318 Pretend that the target
319 .I file
320 has just been modified.
321 When used with the
322 .B \-n
323 flag, this shows you what would happen if you were to modify that file.
324 Without
325 .BR \-n ,
326 it is almost the same as running a
327 .I touch
328 command on the given file before running
329 .BR make ,
330 except that the modification time is changed only in the imagination of
331 .BR make .
332 .TP 0.5i
333 .B \-\-warn\-undefined\-variables
334 Warn when an undefined variable is referenced.
335 .SH "EXIT STATUS"
336 GNU
337 .B make
338 exits with a status of zero if all makefiles were successfully parsed
339 and no targets that were built failed. A status of one will be returned
340 if the
341 .B \-q
342 flag was used and
343 .B make
344 determines that a target needs to be rebuilt. A status of two will be
345 returned if any errors were encountered.
346 .SH "SEE ALSO"
347 The full documentation for
348 .B make
349 is maintained as a Texinfo manual. If the
350 .B info
351 and
352 .B make
353 programs are properly installed at your site, the command
354 .IP
355 .B info make
356 .PP
357 should give you access to the complete manual.
358 .SH BUGS
359 See the chapter ``Problems and Bugs'' in
360 .IR "The GNU Make Manual" .
361 .SH AUTHOR
362 This manual page contributed by Dennis Morse of Stanford University.
363 Further updates contributed by Mike Frysinger. It has been reworked by Roland
364 McGrath. Maintained by Paul Smith.
365 .SH "COPYRIGHT"
366 Copyright \(co 1992-1993, 1996-2016 Free Software Foundation, Inc.
367 This file is part of
368 .IR "GNU make" .
369 .LP
370 GNU Make is free software; you can redistribute it and/or modify it under the
371 terms of the GNU General Public License as published by the Free Software
372 Foundation; either version 3 of the License, or (at your option) any later
373 version.
374 .LP
375 GNU Make is distributed in the hope that it will be useful, but WITHOUT ANY
376 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
377 A PARTICULAR PURPOSE. See the GNU General Public License for more details.
378 .LP
379 You should have received a copy of the GNU General Public License along with
380 this program. If not, see
381 .IR http://www.gnu.org/licenses/ .