To open the /etc/X11/gdm/gdm.conf file for editing in the Pico editor, type pico /etc/X11/gdm/gdm.conf. Press Enter.
To turn off root logins through gdm, go to the AllowRoot=1 command line and replace the 1 with a 0 and then press Enter.
To save the file, you would type Control-X. We will do this for you. Click anywhere on the screen to continue.
To save your changes, select Y for Yes.
Pico now asks what file name you would like to save this file as. To accept the default file name that Pico gives, press Enter.
This completes the simulation.
Configuration File - gdm.conf
The daemon and the accompanying utilities share a common configuration file: etc/gdm/gdm.conf.
The configuration file is divided into sections each containing variables that define the behaviour for a specific part of the GDM suite.
gdm.conf follows the standard GNOME configuration file syntax. Keywords in brackets define sections, strings before an equal sign (=) are variables and the data after equal sign represents their value. In general, 0 represents disable and 1 represents enable for boolean configuration options.