Re: make: existence-only prerequisites (was: make: order-only prerequisites?)

[Taylor R Campbell <campbell+netbsd-tech-userlevel%mumble.net@localhost>]

> Date: Mon, 13 Feb 2017 11:58:18 +0100
> From: Edgar Fuß <ef%math.uni-bonn.de@localhost>
> 
> > I don't remember anything that just checks 'existance'
> > without checking the timestamp.
> Which, to epeat myself,  would be extremely useful, especially for directories
> (because adding a file means updating the directories mtime, which ...).
> I always end up with something like
> 	test -d ${d} || mkdir -p ${d}
> which doesn't feel very make-like.

Traditionally make(1) doesn't handle dependencies on directories very
well for various reasons, and the traditional approach is to use a
dummy file in the directory:

foo/.stamp:
	touch foo/.stamp