File: make.info,  Node: Pattern Rules,  Next: Last Resort,  Prev: Chained Rules,  Up: Implicit Rules

10.5 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.  *Note How to Use Variables: Using Variables, and *note Functions
for Transforming Text: Functions.

* Menu:

* Pattern Intro::               An introduction to pattern rules.
* Pattern Examples::            Examples of pattern rules.
* Automatic Variables::         How to use automatic variables in the
                                  recipe 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.