Switching display managers
More than one desktop environment may be run on the Linux system at any time. If both the KDE and GNOME environments are installed, you may switch between them during the graphical login by selecting the environment from the session menu. Both the KDM and GDM managers will have the session menu available at startup. It is possible to run only one of the display managers, but you can change which display manager is presented during startup. In order to change from the default GDM manager, you will need to update the /etc/sysconfig/desktop file by editing the following:
desktop= "kde" displaymanager= "kdm"
Another way to switch between the KDM and GDM managers is to install the switchdesk tool using a package manager and then execute the application. switchdesk allows users to simply switch between various desktop environments installed on the system. Not all display managers are supported; however, it does support KDE and GNOME:
switchdesk kdeRed Hat Linux switchdesk 4.0 Copyright (C) 1999-2004 Red Hat, Inc Redistributable under the terms of the GNU General Public License Desktop now set up to run KDE.