devdocs/gnu_make/pattern-examples.html


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  <h1 class="subsection">Pattern Rule Examples</h1> <p>Here are some examples of pattern rules actually predefined in <code>make</code>. First, the rule that compiles ‘<samp>.c</samp>’ files into ‘<samp>.o</samp>’ files: </p> <div class="example"> <pre class="example">%.o : %.c
        $(CC) -c $(CFLAGS) $(CPPFLAGS) $&lt; -o $@
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</div> <p>defines a rule that can make any file <samp><var>x</var>.o</samp> from <samp><var>x</var>.c</samp>. The recipe uses the automatic variables ‘<samp>$@</samp>’ and ‘<samp>$&lt;</samp>’ to substitute the names of the target file and the source file in each case where the rule applies (see <a href="automatic-variables">Automatic Variables</a>). </p> <p>Here is a second built-in rule: </p> <div class="example"> <pre class="example">% :: RCS/%,v
        $(CO) $(COFLAGS) $&lt;
</pre>
</div> <p>defines a rule that can make any file <samp><var>x</var></samp> whatsoever from a corresponding file <samp><var>x</var>,v</samp> in the sub-directory <samp>RCS</samp>. Since the target is ‘<samp>%</samp>’, this rule will apply to any file whatever, provided the appropriate prerequisite file exists. The double colon makes the rule <em>terminal</em>, which means that its prerequisite may not be an intermediate file (see <a href="match_002danything-rules">Match-Anything Pattern Rules</a>). </p> <p>This pattern rule has two targets: </p> <div class="example"> <pre class="example">%.tab.c %.tab.h: %.y
        bison -d $&lt;
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</div> <p>This tells <code>make</code> that the recipe ‘<samp>bison -d <var>x</var>.y</samp>’ will make both <samp><var>x</var>.tab.c</samp> and <samp><var>x</var>.tab.h</samp>. If the file <samp>foo</samp> depends on the files <samp>parse.tab.o</samp> and <samp>scan.o</samp> and the file <samp>scan.o</samp> depends on the file <samp>parse.tab.h</samp>, when <samp>parse.y</samp> is changed, the recipe ‘<samp>bison -d parse.y</samp>’ will be executed only once, and the prerequisites of both <samp>parse.tab.o</samp> and <samp>scan.o</samp> will be satisfied. (Presumably the file <samp>parse.tab.o</samp> will be recompiled from <samp>parse.tab.c</samp> and the file <samp>scan.o</samp> from <samp>scan.c</samp>, while <samp>foo</samp> is linked from <samp>parse.tab.o</samp>, <samp>scan.o</samp>, and its other prerequisites, and it will execute happily ever after.) </p><div class="_attribution">
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    <a href="https://www.gnu.org/software/make/manual/html_node/Pattern-Examples.html" class="_attribution-link">https://www.gnu.org/software/make/manual/html_node/Pattern-Examples.html</a>
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