Associations between file types and applications

[Nathan Ridge <zeratul976@hotmail.com>]

Hi,

I'm running Debian stable with KDE. 

I have a question about the way applications are associated with file types.

Based on this documentation [1], I understand that:

  - The associations are derived from *.desktop files located in
     /usr/share/applications and subdirectories.

  - A program called 'update-desktop-database' builds a cache
     of mappings from file types to applications in the file
     /usr/share/applications/mimeinfo.cache.

  - The associations can be customized using a file mimeapps.list.

My questions are:

  (1) If the 'update-desktop-database' program has not yet been
        run on a system, so there is no mimeinfo.cache file, are
        programs that want to query the default application for a
        file type expected to look into the *.desktop files manually?

        I ask this because I'm finding that, for example, GLib, which
        provides an API to query the default application for a file 
        type [2], does not look at the *.desktop files itself if there is 
        no mimeinfo.cache file.

  (2) If the answer to (1) is 'no', should something be automatically
        running 'update-desktop-database' upon system installation
        and after a new application is installed? It doesn't seem like
        something the end-user should have to do to get correct
        associations.

Thanks,
Nate

[1] https://wiki.debian.org/MIME#Application_association
[2] https://developer.gnome.org/gio/stable/GAppInfo.html#g-app-info-get-default-for-type