Re-enable graphical root-login on 12.04 LTS

sudo passwd root
sudo sh -c 'echo "greeter-show-manual-login=true" >> /etc/lightdm/lightdm.conf'

Root won't show up as a user, but "Login" will, which is how you manually log in with users not shown in the greeter.

Rebooted and then you should be able to login as root.


OR

First of all, you must set root 's password.

sudo passwd root
Enter new UNIX password:

Now you have root password. Now activate the root account:

sudo usermod -U root

Then you should allow lightdm, gdm or kdm to allow logging in as root.

To enable this:

In GDM

Edit /etc/gdm/custom.conf file and include AllowRoot=true.

In KDM

Edit /etc/kde4/kdm/kdmrc file and change AllowRootLogin=false for AllowRootLogin=true.

In LightDM

This procedure enables the "Other" menu, so you can type the username root and login. You must edit/etc/lightdm/lightdm.conf and add greeter-show-manual-login=true. Then reboot.

Others session managers have other methods to accomplish this.

As you have noticed I gave the instructions but by any circumstance you should not run the GUI as root. Murphy's Law says that it is likely that you mess up somehow and will be annoyed starting again.

I played around enough, how do I go back?

To disable root login just type:

sudo passwd -dl root