|GNU Make Manual||www.imodulo.com · 2003-04-05|
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The goals are the targets that
make should strive ultimately to update. Other targets are updated as well if they appear as prerequisites of goals, or prerequisites of prerequisites of goals, etc.
By default, the goal is the first target in the makefile (not counting targets that start with a period). Therefore, makefiles are usually written so that the first target is for compiling the entire program or programs they describe. If the first rule in the makefile has several targets, only the first target in the rule becomes the default goal, not the whole list.
You can specify a different goal or goals with arguments to
make. Use the name of the goal as an argument. If you specify several goals,
make processes each of them in turn, in the order you name them.
Any target in the makefile may be specified as a goal (unless it starts with
- or contains an
=, in which case it will be parsed as a switch or variable definition, respectively). Even targets not in the makefile may be specified, if
make can find implicit rules that say how to make them.
Make will set the special variable
MAKECMDGOALS to the list of goals you specified on the command line. If no goals were given on the command line, this variable is empty. Note that this variable should be used only in special circumstances.
An example of appropriate use is to avoid including
.d files during
clean rules (Automatic Prerequisites), so
make won't create them only to immediately remove them again:
sources = foo.c bar.c ifneq ($(MAKECMDGOALS),clean) include $(sources:.c=.d) endif
One use of specifying a goal is if you want to compile only a part of the program, or only one of several programs. Specify as a goal each file that you wish to remake. For example, consider a directory containing several programs, with a makefile that starts like this:
.PHONY: all all: size nm ld ar as
If you are working on the program
size, you might want to say
make size so that only the files of that program are recompiled.
Another use of specifying a goal is to make files that are not normally made. For example, there may be a file of debugging output, or a version of the program that is compiled specially for testing, which has a rule in the makefile but is not a prerequisite of the default goal.
Another use of specifying a goal is to run the commands associated with a phony target (Phony Targets) or empty target (Empty Target Files to Record Events). Many makefiles contain a phony target named
clean which deletes everything except source files. Naturally, this is done only if you request it explicitly with
make clean. Following is a list of typical phony and empty target names. Standard Targets, for a detailed list of all the standard target names which GNU software packages use.
Make all the top-level targets the makefile knows about.
Delete all files that are normally created by running
clean, but may refrain from deleting a few files that people normally don't want to recompile. For example, the
mostlyclean target for GCC does not delete
libgcc.a, because recompiling it is rarely necessary and takes a lot of time.
Any of these targets might be defined to delete more files than
clean does. For example, this would delete configuration files or links that you would normally create as preparation for compilation, even if the makefile itself cannot create these files.
Copy the executable file into a directory that users typically search for commands; copy any auxiliary files that the executable uses into the directories where it will look for them.
Print listings of the source files that have changed.
Create a tar file of the source files.
Create a shell archive (shar file) of the source files.
Create a distribution file of the source files. This might be a tar file, or a shar file, or a compressed version of one of the above, or even more than one of the above.
Update a tags table for this program.
Perform self tests on the program this makefile builds.
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