I'm sure that this question has been asked a few times before, but it's quite hard to find the answer.

What's the %u stand for in the command "firefox %u"? This is the command that is displayed by default with my firefox installation.

I did manage to find one post about this, but the reply was "I forget what it's for, but I do know that it's something useful."

Any takers?

And a second part to this question... I recently found out about Swiftfox and installed it. Since it's an optimized version of Firefox, would it help to add this mysterious %u to it as well?

You're using KDE aren't you? If so, the %u will be a URL parameter. There's some info about the Exec option in .desktop files at http://docs.kde.org/development/en/k...izing-kde.html which should apply to KDE menus as well.

I think it's the URL being passed by the application calling firefox.

If you're interested in the firefox command options, enter firefox -h from a terminal window for a list of them, and the command syntax.

I'm actually using gnome under Ubuntu. It still had the %u there (by "there", I mean in the Applications menu) by default.

Basically, what I sometimes do to see where programs are located, or which command is used to run them, is drag icons from the menu onto the desktop. That way, I can right click it, open up its properties and take a bit of a look around before deleting the icon. That's when I noticed the %u. It is a stock Ubuntu 6.10 install, though, so maybe this kind of thing is useful not only to kde, but to gnome, as well?

I had already tried "firefox -h", but didn't find anything relating to the %.

yea everyone is right
its a matter of kde and gnome using standards i think set for linux desktop. (freedesktop.org ?)
%u is a url i thinf %F is a file.
it has to do with the drag and drop capabilities of the .desktop files.
just like you said you can drag the menu launchers onto the desktop.
and then you can drag documents onto the launcher. this is where the %u comes in to play.
if you dragged a whole folder of files onto the launcher it created lots of different instances of the app. If you write something with tabs and want all the different files in the tabs instead of different instances you use %U instead of %u i think.
the convention has to be written down somewhere for everything you cn do with those .desktop files.
it makes it so developers can make apps with common behavior that integrate into the desktop easy.

Ahhh, now everything makes sense. Thank you for the detailed explanation!