# gmake(1) - man - phpman > **TLDR:** This command is an alias of GNU `make`. > - View documentation for the original command: `tldr make` *Source: tldr-pages* --- [MAKE(1)](https://www.chedong.com/phpMan.php/man/MAKE/1/markdown) User Commands [MAKE(1)](https://www.chedong.com/phpMan.php/man/MAKE/1/markdown) ## NAME make - GNU make utility to maintain groups of programs ## SYNOPSIS **make** [_OPTION_]... [_TARGET_]... ## DESCRIPTION The _make_ utility will determine automatically which pieces of a large program need to be re‐ compiled, and issue the commands to recompile them. The manual describes the GNU implementa‐ tion 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 very 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 rela‐ tionships 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 de‐ scription 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. **make** executes commands in the _makefile_ to update one or more target _names_, where _name_ is typ‐ ically 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**. ### -B --always-make Unconditionally make all targets. ### -C --directory Change to directory _dir_ before reading the makefiles or doing anything else. If multi‐ ple **-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 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. **--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. Use _n_ to disable all previous debugging flags. ### -e --environment-overrides Give variables taken from the environment precedence over variables from makefiles. ### -f --file --makefile Use _file_ as a makefile. ### -i --ignore-errors Ignore all errors in commands executed to remake files. ### -I --include-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 speci‐ fied. 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 al‐ lowed 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 argu‐ ment, **make** will not limit the number of jobs that can run simultaneously. When **make** in‐ vokes a **sub-make,** all instances of make will coordinate to run the specified number of jobs at a time; see the section **PARALLEL** **MAKE** **AND** **THE** **JOBSERVER** for details. **--jobserver-fds** [_R,W_] Internal option **make** uses to pass the jobserver pipe read and write file descriptor num‐ bers to **sub-makes;** see the section **PARALLEL** **MAKE** **AND** **THE** **JOBSERVER** for details ### -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 pro‐ cessed all the same. ### -l --load-average 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, re‐ moves a previous load limit. ### -L --check-symlink-times Use the latest mtime between symlinks and target. ### -n --just-print --dry-run --recon Print the commands that would be executed, but do not execute them (except in certain circumstances). ### -o --old-file --assume-old 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. ### -O --output-sync When running multiple jobs in parallel with **-j**, ensure the output of each job is col‐ lected together rather than interspersed with output from other jobs. If _type_ is not specified or is **target** the output from the entire recipe for each target is grouped to‐ gether. If _type_ is **line** the output from each command line within a recipe is grouped together. If _type_ is **recurse** output from an entire recursive make is grouped together. If _type_ is **none** output synchronization is disabled. ### -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 informa‐ tion given by the **-v** switch (see below). To print the data base without trying to re‐ make any files, use _make_ _-p_ _-f/dev/null_. ### -q --question ``Question mode''. Do not run any commands, or print anything; just return an exit sta‐ tus 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 suf‐ fixes for suffix rules. ### -R --no-builtin-variables Don't define any built-in variables. ### -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 **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 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**. ### --trace Information about the disposition of each target is printed (why the target is being re‐ built and what commands are run to rebuild it). ### -v --version Print the version of the **make** 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 **make** commands. ### --no-print-directory Turn off **-w**, even if it was turned on implicitly. ### -W --what-if --new-file --assume-new 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**. ### --warn-undefined-variables Warn when an undefined variable is referenced. ## EXIT STATUS GNU **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 **-q** flag was used and **make** determines that a target needs to be rebuilt. A status of two will be returned if any errors were encountered. ## SEE ALSO The full documentation for **make** is maintained as a Texinfo manual. If the **info** and **make** pro‐ grams are properly installed at your site, the command **info** **make** should give you access to the complete manual. Additionally, the manual is also available on‐ line at _ ## PARALLEL MAKE AND THE JOBSERVER Using the _-j_ option, the user can instruct **make** to execute tasks in parallel. By specifying a numeric argument to _-j_ the user may specify an upper limit of the number of parallel tasks to be run. When the build environment is such that a top level **make** invokes **sub-makes** (for instance, a style in which each sub-directory contains its own _Makefile_ ), no individual instance of **make** knows how many tasks are running in parallel, so keeping the number of tasks under the upper limit would be impossible without communication between all the **make** instances running. While solutions like having the top level **make** serve as a central controller are feasible, or using other synchronization mechanisms like shared memory or sockets can be created, the current implementation uses a simple shared pipe. This pipe is created by the top-level **make** process, and passed on to all the **sub-makes.** The top level **make**process**writes** **N-1** one-byte tokens into the pipe (The top level **make** is assumed to reserve one token for itself). Whenever any of the **make** processes (including the top-level **make** ) needs to run a new task, it reads a byte from the shared pipe. If there are no tokens left, it must wait for a token to be written back to the pipe. Once the task is completed, the **make** process writes a token back to the pipe (and thus, if the tokens had been exhausted, unblocking the first **make** process that was waiting to read a token). Since only **N-1** tokens were written into the pipe, no more than **N** tasks can be running at any given time. If the job to be run is not a **sub-make** then **make** will close the jobserver pipe file descrip‐ tors before invoking the commands, so that the command can not interfere with the _jobserver,_ and the command does not find any unusual file descriptors. ## BUGS See the chapter ``Problems and Bugs'' in _The_ _GNU_ _Make_ _Manual_. ## AUTHOR This manual page contributed by Dennis Morse of Stanford University. Further updates con‐ tributed by Mike Frysinger. It has been reworked by Roland McGrath. Maintained by Paul Smith. ## COPYRIGHT Copyright © 1992-1993, 1996-2016 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 3 of the License, 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 this program. If not, see _. GNU 28 February 2016 [MAKE(1)](https://www.chedong.com/phpMan.php/man/MAKE/1/markdown)