How do I switch from the default display manager (Lightdm) to the older display manager (GDM)?
Switching from LightDM to the "older" GDM is very easy, and need not even involve opening a terminal.
- If you need/want to do this from a terminal (e.g. recovery console), please scroll below the screenshots for a how-to.
- Also, the "new" GDM is not covered here because it is not officially available for 12.04 and the unofficial packages do not work for most users.
Easily switch to GDM with the Software Centre
Open the Software Center, type "gdm" in the search box, and click on Install as shown below, or click on this button: gdm
After you enter your password, you will get the configuration screen shown below. Change lightdm to gdm and click on Forward:
Restart your computer, and you should now have the "old" GDM login screen; note that you can still select from any available session, including Ubuntu (3D), Ubuntu 2D, Gnome, Gnome Classic, etc.
Switch to GDM via the terminal
Open a terminal with Ctrl+Alt+T if you are on the desktop and not in the recovery console.
sudo apt-get install gdm, and then your password when prompted or run
sudo dpkg-reconfigure gdmthen sudo service lightdm stop, in case gdm is already installed.
A "Package Configuration" dialog will be displayed; click OK to proceed to the below screen. Use the arrow-keys to select
lightdm, press Tab to move to OK, and press Enter.
Reboot the computer (you can do this with
sudo rebootif in the recovery console).
These did not work for me for newer versions of
gdm. I had to use
gdm3 instead of
sudo dpkg-reconfigure gdm3
Gnome-display-manager is not broken in 12.04 (or at least it works fine for me), There is no need to reboot the machine. You ran the right commands, but maybe try it this way, also might want to
sudo apt-get install gdm just to make sure you have the working version.
sudo dpkg-reconfigure gdm then
sudo service lightdm stop
after this you will need to press alt+f2 and login from command line.
Then you will be able to start
sudo service gdm start separably.
additionally what luis alvez wrote above, for systemd managed systems (15.10 e.g.) use:
systemctl service stop lightdm systemctl service start gdm
sudo service lightdm stop
Choosing Between lightdm and gdm
Reverting from lightdm to gdm is extremely easy if you have not entered a wrong command in the terminal.
You just need to open the terminal and type the following command:
sudo dpkg-reconfigure lightdm
Enter your password and two dialog boxes will appear after one another (Similar to those which appeared while installing lightdm).
Press enter to select 'OK' for first dialog box and then choose between gdm and lightdm in the second dialog box.
Restart your PC.
Hope that helps!
additionally to the answers, to use gdm3 and stop lightdm on Ubuntu 18.04:
sudo dpkg-reconfigure gdm3 systemctl stop lightdm systemctl start gdm3