PhonyTargets

Here is a fragment that illustrates how to make Phony targets that run commands. The AlwaysBuild line makes sure the command runs even if there happens to be a file named the same as the target.

def PhonyTarget(target, action):
    phony = Environment(ENV=os.environ, BUILDERS={"phony": Builder(action=action)})
    AlwaysBuild(phony.phony(target=target, source="SConstruct"))


PhonyTarget("TAGS", "tools/mktags.sh -e")

Here's a better implementation that handles multiple targets and doesn't require generating an Environment every time.

def PhonyTargets(env=None, **kw):
    if not env:
        env = DefaultEnvironment()
    for target, action in kw.items():
        env.AlwaysBuild(env.Alias(target, [], action))


PhonyTargets(TAGS="tools/mktags.sh -e")

env = Environment(parse_flags="-std=c89 -DFOO -lm")
PhonyTargets(
    env, CFLAGS="@echo $CFLAGS", DEFINES="@echo $CPPDEFINES", LIBS="@echo $LIBS"
)

The output looks like this:

$ scons TAGS
tools/mktags.sh -e
 ...
$ scons CFLAGS
-std=c89
$ scons DEFINES
FOO
$ scons LIBS
m