Enabling root login with Graphical Desktop isn't recommended for regular use. Use with caution and only on special ocassions.
Open terminal and switch to the superuser (root):
su -
Enter the root password and you are logged in as root in the terminal.
Edit the file /etc/pam.d/gdm with your favorite text editor:
vi /etc/pam.d/gdm
OR
gedit /etc/pam.d/gdm
Find the following line:
auth required pam_succeed_if.so user != root quiet
Comment it to
#auth required pam_succeed_if.so user != root quiet
Do the same with the file /etc/pam.d/gdm-password
You can login to GDM as root from the next time.
Alternative Technique : Since it is the GUI that prevents you to login as root, you can login in run level 3 then start the X Windows system to get root up on Gnome or any other desktop environment.
Do this :
Modify your bootloader configuration to set system boot into runlevel 3.
Grub is the default bootloader for most systems. /etc/grub.conf is a soft link to its configuration file which resides on /boot actually.
Let us open it with our favorite text editor.
vi /etc/grub.conf
OR if you are on GUI and if you are comfortable with gedit
gedit /etc/grub.conf
Find the block item for your boot target with a kernel entry.
Mine happens to be:
kernel /vmlinuz-2.6.38.6-27.fc15.i686 ro
root=UUID=3a141363-91f4-4cf0-9b11-968251eec075 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM
Append 3 as another parameter to the end to make it
kernel /vmlinuz-2.6.38.6-27.fc15.i686 ro
root=UUID=3a141363-91f4-4cf0-9b11-968251eec075 rd_NO_LUKS rd_NO_LVM rd_NO_MD rd_NO_DM 3
Save and close the file.
The next time you login, you will be presented with login on terminal
instead of GUI. Use ‘root’ for login and the
root password you set during the system installation for password. After
you’ve successfully logged in, enter startx
.
This will start the default Graphical Desktop Manager.