I would like to have files of a chosen type (by their extension) to open with some specific programs. Which configuration files do I need to edit?
I've tried some in
/usr/share/appplications/default.list but it doesn't work.
Have a look at the file
There is a section
[Default Applications] to specify the programs for particular mime types. You can add for example:
.desktop files can be found in
/usr/share/applications/ or you can create your own files under
$HOME/.local/share/applications/. To find out the mime type of the files, run
file --mime-type <some_file>
Alternatively, in KDE one can accomplish the same in GUI in File Associations inside System Settings.
To register a MIME type for an extension see freedesktop.org - AddingMIMETutor and stackoverflow - Register file extensions / mime types in Linux.