File: make.info,  Node: Empty Recipes,  Prev: Recipes.php">Canned Recipes,  Up: Recipes

5.9 Using Empty Recipes
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It is sometimes useful to define recipes which do nothing.  This is done
simply by giving a recipe that consists of nothing but whitespace.  For
example:

     target: ;

defines an empty recipe for 'target'.  You could also use a line
beginning with a recipe prefix character to define an empty recipe, but
this would be confusing because such a line looks empty.

   You may be wondering why you would want to define a recipe that does
nothing.  One reason this is useful is to prevent a target from getting
implicit recipes (from implicit rules or the '.DEFAULT' special target;
*note Implicit Rules:: and *note Defining Last-Resort Default Rules:
Last Resort.).

   Empty recipes can also be used to avoid errors for targets that will
be created as a side-effect of another recipe: if the target does not
exist the empty recipe ensures that 'make' won't complain that it
doesn't know how to build the target, and 'make' will assume the target
is out of date.

   You may be inclined to define empty recipes for targets that are not
actual files, but only exist so that their prerequisites can be remade.
However, this is not the best way to do that, because the prerequisites
may not be remade properly if the target file actually does exist.
*Note Phony Targets: Phony Targets, for a better way to do this.