12.15 Single Suffix Rules and Separated Dependencies

A Single Suffix Rule is basically a usual suffix (inference) rule (‘.from.to:’), but which destination suffix is empty (‘.from:’).

Separated dependencies simply refers to listing the prerequisite of a target, without defining a rule. Usually one can list on the one hand side, the rules, and on the other hand side, the dependencies.

Solaris make does not support separated dependencies for targets defined by single suffix rules:

     $ cat Makefile
     .SUFFIXES: .in
     foo: foo.in
     .in:
             cp $< $@
     $ touch foo.in
     $ make
     $ ls
     Makefile  foo.in

while GNU Make does:

     $ gmake
     cp foo.in foo
     $ ls
     Makefile  foo       foo.in

Note it works without the ‘foo: foo.in’ dependency.

     $ cat Makefile
     .SUFFIXES: .in
     .in:
             cp $< $@
     $ make foo
     cp foo.in foo

and it works with double suffix inference rules:

     $ cat Makefile
     foo.out: foo.in
     .SUFFIXES: .in .out
     .in.out:
             cp $< $@
     $ make
     cp foo.in foo.out

As a result, in such a case, you have to write target rules.