Rules for cleaning the directory
Compiling a program is not the only thing you might want to write rules for. Makefiles commonly do a few other things besides compiling a program: for example, they can often delete all the object files and executables so that the directory is clean.
Here is how we could write a
make rule for cleaning our
clean: rm edit $(objects)
In practice, we might want to write the rule in a somewhat more
complicated manner to handle unanticipated situations. For example:
.PHONY : clean clean : -rm edit $(objects)
make from getting confused by an actual file
clean and causes it to continue in spite of errors from
A rule such as this should not be placed at the beginning of the
makefile, because we do not want it to run by default! Thus, in the
example makefile, we want the rule for
edit, which recompiles
the editor, to remain the default goal.
clean is not a prerequisite of
edit, this rule will
not run at all if we give the command
make with no arguments.
In order to run the rule, we have to type