This is useful in two cases.

• You want just dependencies, no commands. Use the following for an example.

kbd.o command.o files.o: command.h

This input gives an additional dependency to each of the three object files mentioned.

• Similar commands work for all the targets. The commands do not need to be absolutely identical, since the automatic variable ‘$@’ can be used to substitute the particular target to be remade into the commands (see Automatic Variables). Use the following for an example.

bigoutput littleoutput : text.g

        generate text.g -$(subst output,,$@) > $@

This input is equivalent to the next example.

bigoutput : text.g
        generate text.g -big > bigoutput
littleoutput : text.g
        generate text.g -little > littleoutput

Here we assume the hypothetical program, generate, makes two types of output, one if given ‘-big’ and one if given ‘-little’. See Functions for string substitution and analysis for an explanation of the subst function.

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 Static pattern rules.