File: make.info,  Node: Force Targets,  Next: Empty Targets,  Prev: Phony Targets,  Up: Rules

4.7 Rules without Recipes or Prerequisites
==========================================

If a rule has no prerequisites or recipe, and the target of the rule is
a nonexistent file, then 'make' imagines this target to have been
updated whenever its rule is run.  This implies that all targets
depending on this one will always have their recipe run.

   An example will illustrate this:

     clean: FORCE
             rm $(objects)
     FORCE:

   Here the target 'FORCE' satisfies the special conditions, so the
target 'clean' that depends on it is forced to run its recipe.  There is
nothing special about the name 'FORCE', but that is one name commonly
used this way.

   As you can see, using 'FORCE' this way has the same results as using
'.PHONY: clean'.

   Using '.PHONY' is more explicit and more efficient.  However, other
versions of 'make' do not support '.PHONY'; thus 'FORCE' appears in many
makefiles.  *Note Phony Targets::.