Make

Automatic variables

$@ The name of the target

$< The name of the first prerequisite

$? The names of all the prerequisites that are newer than the target

$^ The names of all the prerequisites

$* The stem with which the rule matches

Valid only in recipes, they are undefined in targets or prerequisites ^[1] .

Examples

target: requisite1 requisite2 requisite3

requisite3 is the only prerequisite newer than target. In the recipe for this rule:

‘$@’ is target

‘$<’ is requisite1

‘$?’ is requisite3

‘$^’ is requisite1 requisite2 requisite3

file.zip: a b c
         zip -r $@ $?

Only those files newer than file.zip will be replaced, or added if they don’t exist in file.zip.

References

1. Make > Using Implicit Rules > Defining and Redefining Pattern Rules > 10.5.3 Automatic Variables