Pattern Rules

[ Up: Implicit Rules ]
[ Previous: Chained Rules ][ Next: Last Resort ]

---

Defining and Redefining Pattern Rules

You define an implicit rule by writing a pattern rule. A pattern rule looks like an ordinary rule, except that its target contains the character % (exactly one of them). The target is considered a pattern for matching file names; the % can match any nonempty substring, while other characters match only themselves. The prerequisites likewise use % to show how their names relate to the target name.

Thus, a pattern rule %.o : %.c says how to make any file stem.o from another file stem.c.

Note that expansion using % in pattern rules occurs after any variable or function expansions, which take place when the makefile is read. How to Use Variables, and Functions for Transforming Text.

Menu

• Pattern Intro :: An introduction to pattern rules.
• Pattern Examples :: Examples of pattern rules.
• Automatic :: How to use automatic variables in the commands of implicit rules.
• Pattern Match :: How patterns match.
• Match-Anything Rules :: Precautions you should take prior to defining rules that can match any target file whatever.
• Canceling Rules :: How to override or cancel built-in rules.