Re: Retrieving the "include" directory for Emacs Modules

[Stefan Monnier via Users list for the GNU Emacs text editor <help-gnu-emacs@gnu.org>]

> Those under /usr/lib are looked in by the relevant compilers (they are
> include directories private to those compilers, hard-coded into them
> when they are built).  Those under /usr/share are private to the
> relevant packages, and are either examples or test suites (thus AFAIU
> unrelated to the issue at hand here).  Those under /usr/src are what I
> mentioned: private headers needed to build a package.

Indeed, they each have their own reason to exist.  And this is in Debian,
i.e. a distribution which is very careful to install things in the one
central place where they belong.
Other relevant cases will look very different:
Emacs.app, AppImages, Snap packages, etc...


        Stefan