Eli Zaretskii <eliz@gnu.org> writes:

> More generally, I'm not sure mailcap is the right tool for the job:
> its main purpose is to view attachments to email messages, where we
> generally have metadata (MIME etc.) which is not necessarily available
> for arbitrary disk files.

Isn't that just "file --mime-type -b"?  file is a BSD command AFAICT so
it should presumably be available almost everywhere.

I also see in the man page than a certain Reuben Thomas has been
involved in its development so maybe he has something to add here.  :-)