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| '''`make(1)`''' is a generic toolchain for compiling software. It is part of the POSIX standard, though GNU make has some slight differences to BSD make. | '''`make(1)`''' is a build system. While part of the POSIX standard, GNU `make(1)` has slight divergences in behavior. |
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| == Rules == | == Installation == |
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| A rule has three components: a '''target''', 0 or more '''prerequisites''', and 0 or more '''recipes'''. | All [[Linux]] and [[BSD]] distributions offer a `make` package. |
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| {{{ hello: hello.cpp g++ -o hello hello.cpp }}} `hello` is a target. With this `Makefile` in the working directory, it can be built by calling `make hello` in a terminal. `hello.cpp` is a prerequisite. There can be any number of prerequisites; anything after the colon on the target line is treated as one. Before `hello` can be built, this prerequisite must be satisfied by either... * running another rule to build `hello.cpp` * locating `hello.cpp` as a file in the working directory * Note: if a prerequisite is satisfied with a file '''and''' it is older than the target file, `make(1)` will short circuit as the target does not need to be re-built The remainder is a recipe. Every tabbed, newline-delimited line following a target line is a recipe. Each recipe is run in a discrete subprocess. === Noisy Rules === When executing a rule, each recipe is printed to the terminal before the recipe is executed. This can improve debugging. This can also create an extremely noisy terminal. To make a recipe ''not'' print before executing, prefix it with `@`. To make a recipe silent, redirect the output (i.e. `>/dev/null 2>&1`). If errors can be ignored, consider adding `|| true` to the end. === Variables in Rules === Each recipe is executed in a discrete subprocess. As such, changes to environment variables disappear after execution. {{{ demo: @export DEMO="YES" @echo "Do variables carry over between recipes? $${DEMO:-NO}!" }}} This will print `Do variables carry over between recipes? NO!`. |
Especially on BSD distributions, it may be necessary to specifically install GNU `make(1)`. This is usually available as `gmake`. |
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| == Phony Rules == `make(1)` can also be used to automate processes that aren't necessarily about making a file. A common example is a `clean` rule. |
== Usage == |
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| .PHONY: clean clean: rm -f hello |
make [TARGET] |
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| The `.PHONY` component ensures that `make(1)` does not look for a `clean` file. If there were such a file, `make(1)` might short circuit; it would believe that the rule is already satisfied. | If a target is not specified, the default target is used. === Recipes === Recipes define the build process for a target. See [[Makefile]] for details. |
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| == Pattern Rules == | == See also == |
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| Many programs have a generic and abstract-able build process. Consider the following: | [[https://man.archlinux.org/man/make.1|make(1)]] |
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| {{{ %.o : %.c $(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@ }}} |
[[https://man.archlinux.org/man/make.1p|make(1p)]] |
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| For any `foo.o` file, `make(1)` knows that it can be built with `cc -c foo.c -o foo.o`. === Automatic Variables === Automatic variables are critical to making use of pattern rules. These are populated for every rule. ||'''Variable'''||'''Contents'''|| ||`$@` ||file name of the target|| ||`$^` ||names of '''all''' the prerequisites, with spaces between them|| ||`$<` ||name of the '''first''' prerequisite|| ||`$?` ||names of '''all''' the prerequisites that are newer than the target, with spaces between them|| |
[[Makefile]] |
Make
make(1) is a build system. While part of the POSIX standard, GNU make(1) has slight divergences in behavior.
Contents
Installation
All Linux and BSD distributions offer a make package.
Especially on BSD distributions, it may be necessary to specifically install GNU make(1). This is usually available as gmake.
Usage
make [TARGET]
If a target is not specified, the default target is used.
Recipes
Recipes define the build process for a target. See Makefile for details.