File: make.info,  Node: Pattern Examples,  Next: Automatic Variables,  Prev: Pattern Intro,  Up: Pattern Rules

10.5.2 Pattern Rule Examples
----------------------------

Here are some examples of pattern rules actually predefined in 'make'.
First, the rule that compiles '.c' files into '.o' files:

     %.o : %.c
             $(CC) -c $(CFLAGS) $(CPPFLAGS) $< -o $@

defines a rule that can make any file 'X.o' from 'X.c'.  The recipe uses
the automatic variables '$@' and '$<' to substitute the names of the
target file and the source file in each case where the rule applies
(*note Automatic Variables::).

   Here is a second built-in rule:

     % :: RCS/%,v
             $(CO) $(COFLAGS) $<

defines a rule that can make any file 'X' whatsoever from a
corresponding file 'X,v' in the sub-directory 'RCS'.  Since the target
is '%', this rule will apply to any file whatever, provided the
appropriate prerequisite file exists.  The double colon makes the rule
"terminal", which means that its prerequisite may not be an intermediate
file (*note Match-Anything Pattern Rules: Match-Anything Rules.).

   This pattern rule has two targets:

     %.tab.c %.tab.h: %.y
             bison -d $<

This tells 'make' that the recipe 'bison -d X.y' will make both
'X.tab.c' and 'X.tab.h'.  If the file 'foo' depends on the files
'parse.tab.o' and 'scan.o' and the file 'scan.o' depends on the file
'parse.tab.h', when 'parse.y' is changed, the recipe 'bison -d parse.y'
will be executed only once, and the prerequisites of both 'parse.tab.o'
and 'scan.o' will be satisfied.  (Presumably the file 'parse.tab.o' will
be recompiled from 'parse.tab.c' and the file 'scan.o' from 'scan.c',
while 'foo' is linked from 'parse.tab.o', 'scan.o', and its other
prerequisites, and it will execute happily ever after.)