Change Autologin settings in Ubuntu 10.04 Lucid Lynx from the terminal

While setting up my home server I made the [stupid] mistake of deleting the user that was configured for auto login. After searching for an hour I figured out that the remedy for this is quite simple.

First, switch to a virtual terminal (CTRL + ALT + F1), then login as a working user with sudo privileges.

Edit the file /etc/gdm/custom.conf using nano, vim, or some other text mode text editor. Note that the typical configuration file is /etc/gdm/gdm.conf but this file was not present on my system and the values were in the custom.conf file instead.

If using nano you would type:
sudo nano /etc/gdm/custom.conf

The lines you want to change are "AutomaticLogin=" and "TimedLogin="

Change these to the [existing] user you want to be automatically logged in.

Another option is to delete the values mentioned above and edit the lines "AutomaticLoginEnable=" and "TimedLoginEnable=" and set them to false.

Save and reboot.

Done.