Hi Alejandro,
I think the source of the confusion is that "Should normally be" and how
you should write a default value don't match up because it is normal to
use non-default values.
So systems are commonly set up with localstatedir=/usr/var and
runstatedir=/var/run, despite the fact that their defaults are
$prefix/var and the result of appending /run to it. The reason to give
the defaults in this form is so that, when someone sets prefix to
/usr/local, they (by default) get /usr/local/var and /usr/local/var/run
and thus conform to "how your non-system GNU install should work" rather
than stomping on where things would have been if you'd hard-coded what
many folk do in fact set up. This way, if someone sets things up
differently, you play nicely with their choices, rather than hard-coding
what "everyone" else does.
It's about whoever administers a particular box being at liberty to do
what they want, so if you're writing software to offer to others to
install on their systems, your defaults should be "polite" and not
impose on them any particular set-up.
Does that make it clearer ?
Eddy.
