Housekeeping for Multiple Desktops
If you have multiple desktop environments installed on an Ubuntu box, you'll have to deal with a few housekeeping issues. First, it's easy to end up with boot graphics and a log-in screen you don't want. For instance, I wanted to have KDE on my machine, but I'm not up for the blue Kubuntu boot graphics or the kdm display manager--I want the standard brown Ubuntu boot graphics and gdm popping up with Ubuntu's default theme. So after installing kubuntu-desktop, I had to put those elements back in place.
Choosing boot graphics: To select artwork for the boot and shutdown screens, enter the following two commands in a Terminal window:
sudo update-initramfs -u
After you enter the first command, you'll be given a choice among Ubuntu, Kubuntu, or Xubuntu-themed artwork (assuming you've installed these desktop meta-packages). Type the number that corresponds to your choice and press Enter. Then issue the second command (which will take a few moments to run; have patience).
Tweaking the display manager: The following command will let you switch between gdm and kdm:
Replacing gdm with kdm in that command will yield the same result--either way, you'll see the same text-based chooser you saw when you first installed a new desktop meta-package. Select kdm or gdm with the keyboard. Easy enough. But if you've chosen gdm, you may have one more step. If on boot you see an Ubuntu-style log-in when you expected an Xubuntu-style log-in (or vice versa), here's the command you need:
In the dialog box that pops up, go to the Local tab, make sure 'Style' is set to 'Themed' and 'Theme' is set to 'Selected only', and then choose either the Human or the Xubuntu theme from the list. Also note the 'Background color' widget here; it lets you set the color of the blank screen that appears before and after gdm's log-in screen.
Sending it all back: So you've given a different desktop a try, and you realize you hate it and want to reclaim the space on your drive now taken up by the packages for that foul, alien environment? No problem. This is why we used Aptitude to install our desktop packages--it more or less remembers everything that came along for the ride and can send it all back from whence it came. The command you'll need is:
Just substitute ubuntu-desktop or xubuntu-desktop if either of those was the meta-package you added to your installation.