A rule with multiple targets is equivalent to writing many rules, each with one target, and all identical aside from that. The same commands apply to all the targets, but their effects may vary because you can substitute the actual target name into the command using `$@'. The rule contributes the same dependencies to all the targets also.
This is useful in two cases.
kbd.o command.o files.o: command.hgives an additional dependency to each of the three object files mentioned.
bigoutput littleoutput : text.g generate text.g -$(subst output,,$@) > $@is equivalent to
bigoutput : text.g generate text.g -big > bigoutput littleoutput : text.g generate text.g -little > littleoutputHere we assume the hypothetical program
generatemakes two types of output, one if given `-big' and one if given `-little'. See section Functions for String Substitution and Analysis, for an explanation of the
Suppose you would like to vary the dependencies according to the target, much as the variable `$@' allows you to vary the commands. You cannot do this with multiple targets in an ordinary rule, but you can do it with a static pattern rule. See section Static Pattern Rules.
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