I tried to google this a bit, but all I came up with is how to write a mime types xml file, not what I want.

How do I (gnome and/or kde) set the which programs to associate with a mime type SYSTEM WIDE?

e.g. When I right click on a *.m3u (audio/mpegurl) file in gnome it has "Open with RealPlayer" as default and then another list which includes totem, gvim etc...

How do I tell gnome to use totem as default player? SYSTEM WIDE?

THanks

I doubt if it's possible (easily at least) to do it system-wide; mime types aren't that important for Linux as they are for Windows for example (Linux doesn't usually care about file suffixes, and you can use tools such as file to determine a file's type instead) and I believe the usage of mimetypes is based on your desktop environment (KDE, Gnome, ...) and because they don't all work the same way, you usually have to do the configuration per desktop environment. Well, usually people only use one desktop environment so that's easy.

EDIT: on Windows if you have a .m3u file, Windows tells you it's audio/mpegurl (or whatever) usually even if you rename a .jpg file to be .m3u. On Linux, on the other hand, you can rename all your image files .m3u (or those m3u files .jpg) and they should still work; desktop environments that use mime types (acknowledge .xxx from the filename) may get fooled but on a wider scale it doesn't matter. You can have filenames like somefile.jpg.mp3.aac.cad and it's all the same for Linux -- if you issue

Code:

file somefile.jpg.mp3.aac.cad

then you'll probably get to know what the file really is, as long as 'file' knows about such filetypes.

This is interesting. Here I am trying to figure this out by reading the various files in /usr/share/mime and /etc/mimetype

I think you are right, the xml files in /usr/share/mime just defines an mimetypes without specifying how to identify it from the filename (e.g. using some regexp match). And in /etc/mimtetypes, there are lines such as That seems to do such thing. I am not so clear on what responsibilities are delegated to each configuration files

On the other hand, suppose I now give up on system-wide configuration. If I ask GNOME or KDE to use say xpdf to open an application/pdf file, where is this configuration information stored? In some plain text (xml??) file or in binary form. It is sometimes interesting and necessary to be able to mess with such file by hand...

EDIT: I finally found the answer to my original question. Check the file
/usr/share/applications/mimeinfo.cache