The system in question is Solaris, using the Gnome type interface (Java Desktop Environment). We have occasional issues with users managing to mess up their file assocations (most notably .tif). Trying to find out what files to edit from a command line to change those file associations. (as logging in graphically as them to use the desktop utilities can be a bit of a problem remotely).
Xdg-utils is used for configuring (sort of) desktop environments in terms of things like which app opens which type of file. I once had (darn, can't find it now, I'll try to track it down and post it) a script that works like Mac OS X's open command. It mainly used xdg-open.
Note that this is not specific to Gnome; Xdg-utils works with e.g. KDE, Xfce, fluxbox etc.
You need to edit
p.s. there may be a command line tool I'm not aware of which does this for you ... I like sed though ;)
This particular location is often correct for Ubuntu installations and some other operating systems where gnome is the default window manager (although sometimes it is in
If you're in luck, it will use the XDG_* environment variables, explained here: http://developer.gnome.org/menu-spec/
If it is not there and you don't have those envrionment variables set, you can try using find:
Sometimes, a slightly different system is used; On my laptop I use LXDE (which I recommend, btw),
If you still can't sort it out, I think you'll need to give more information about why your linux version, window manager version and so on.