Re: Updating dired-guess-shell-alist-default

[Michael Welsh Duggan <mwd@md5i.com>]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Yuri Khan <yuri.v.khan@gmail.com>
>> Date: Wed, 8 Jul 2020 02:52:07 +0700
>> Cc: "Philip K." <philip@warpmail.net>, Emacs developers <emacs-devel@gnu.org>
>> 
>> On Wed, 8 Jul 2020 at 02:24, Eli Zaretskii <eliz@gnu.org> wrote:
>> 
>> > I mean, you said our current database is "not modern", so that
>> > probably means xdg-open invokes other programs, and I think it would
>> > be good to know the differences, so we have something tangible to talk
>> > about.
>> 
>> What xdg-open invokes depends on the installed applications and, if
>> multiple applications are registered for handling a MIME type, on user
>> preferences.
>> 
>> On Windows, the closest analogy is file type associations via the registry.
>> 
>> Both are better than a hard-coded list of applications that might or
>> might not be installed on the user’s machine, and, if installed, might
>> or might not be their preference.
>
> Thanks, I think everyone agrees with these general principles.  I was
> asking whether we have enough information to provide practical
> solutions for Posix hosts that don't have xdg-open.

I looked into this a little, and it seems that this is more complicated
than I thought it might be.  I found this post on stackexchange:
https://unix.stackexchange.com/questions/144047/how-does-xdg-open-do-its-work

Seeing that xdg-open is a shell script, I poked around a little, and
there's an extensive tree of programs to use to try and figure out what
to do.  Even open_generic runs the gamut of using xdg-mime, using
mailcap, using mimeopen, and more.  In essence, xdg-open goes through a
lot of testing and checks to try to find a xdg-open-like program to
which it can delegate the opening of the file.

Most of the major desktops seem to have a way to maintain the file to
program mapping, but they all seem to do it differently.

-- 
Michael Welsh Duggan
(md5i@md5i.com)