Re: Question on updating to 29.1

[Eli Zaretskii <eliz@gnu.org>]

> Date: Sat, 12 Aug 2023 00:04:07 +0200
> From: Jens Schmidt <jschmidt4gnu@vodafonemail.de>
> 
> On 2023-08-11  13:16, Eli Zaretskii wrote:
> 
> >> Maybe just a short sentence about this can be added to the INSTALL/README files?
> > 
> > A short sentence that basically says there's nothing special to do
> > when you already have an older version installed?  Why is this needed?
> > In general, if there's no problem, we don't say in the instructions
> > that there's no problem ;-)
> 
> Now that's interesting: Suppose we have file foobar.el(c) from Emacs 28
> installed by "make install" somewhere below, say, /usr/local/...
> 
> Suppose further foobar.el got removed in Emacs 29.  Will it be actively
> removed from /usr/local/... by a "make install" of Emacs 29?

No.  And there's no need to, see below.

> Not sure whether this is what is worrying the OP, but that (and, more 
> generally, version consistency issues) would worry me if used "make
> install" to "upgrade" a local installation.
> 
> Or have I missed something here?

I think you have missed that Lisp files are installed into a
version-specific subdirectory of /usr/local/share/ (as in
/usr/local/share/emacs/29.1/lisp/).  So files installed with some
version of Emacs are in the directory not searched by another version.

The Emacs installation method is designed in a way that allows you to
have several Emacs versions installed on the same system.  Only one of
them, the one you installed the last, is invoked by the name "emacs",
but all the others can be invoked by their numbered names, as in
"emacs-28.2" etc.  An installed version of Emacs will only be removed
if you explicitly run "make uninstall" in the build directory of that
version.