A rule appears in the makefile and says when and how to remake certain files, called the rule’s targets (most often only one per rule). It lists the other files that are the prerequisites of the target, and the recipe to use to create or update the target.
The order of rules is not significant, except for determining the
default goal: the target for
make to consider, if you do
not otherwise specify one. The default goal is the target of the first
rule in the first makefile. If the first rule has multiple targets,
only the first target is taken as the default. There are two
exceptions: a target starting with a period is not a default unless it
contains one or more slashes, ‘
/’, as well; and, a target that
defines a pattern rule has no effect on the default goal.
(See Defining and Redefining Pattern Rules.)
Therefore, we usually write the makefile so that the first rule is the
one for compiling the entire program or all the programs described by
the makefile (often with a target called ‘
See Arguments to Specify the Goals.
|• Rule Example||An example explained.|
|• Rule Syntax||General syntax explained.|
|• Prerequisite Types||There are two types of prerequisites.|
|• Wildcards||Using wildcard characters such as ‘*’.|
|• Directory Search||Searching other directories for source files.|
|• Phony Targets||Using a target that is not a real file’s name.|
|• Force Targets||You can use a target without a recipe
or prerequisites to mark other targets as phony.
|• Empty Targets||When only the date matters and the
files are empty.
|• Special Targets||Targets with special built-in meanings.|
|• Multiple Targets||When to make use of several targets in a rule.|
|• Multiple Rules||How to use several rules with the same target.|
|• Static Pattern||Static pattern rules apply to multiple targets
and can vary the prerequisites according to the target name.
|• Double-Colon||How to use a special kind of rule to allow
several independent rules for one target.
|• Automatic Prerequisites||How to automatically generate rules giving
prerequisites from source files themselves.