Linux Display Managers

Debian/Ubuntu

/etc/X11/default-display-manager

RedHat/CentOS/Fedora

/etc/sysconfig/desktop

OpenSuSe

/etc/sysconfig/displaymanager


OR on systemd systems, do;


systemctl status display-manager


To switch Display Managers (Debian)

sudo dpkg-reconfigure <displayManagerName>

Actually with the above, we can use any installed DisplayManager and then from the prompt, simply choose the one we wish to switch to.

To restart the Display Manager (Debian), do;

sudo service <displayManager> restart

Example: sudo service gdm restart

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See also here 

and here for the good old RedHat logo, which is a must for any Applications Menu logo.