The GDM package provides the following different commands in EXPANDED_SBINDIR intended to be used by the root user:
The gdm command is really just a script which runs the gdm-binary, passing along any options. Before launching gdm-binary, the gdm wrapper script will source the <etc>/profile file to set the standard system environment variables. In order to better support internationalization, it will also set the LC_MESSAGES environment variable to LANG if neither LC_MESSAGES or LC_ALL are set. If you really need to set some additional environment before launching GDM, you can do so in this script.
Gives a brief overview of the command line options.
If this option is specified, then GDM does not fork into the background when run. You can use just a single dash with this option to preserve compatibility with XDM.
Tell the daemon that it should not run anything on the console. This means that none of the local servers from the [servers] section will be run, and the console will not be used for communicating errors to the user. An empty [servers] section automatically implies this option.
Specify an alternative configuration file.
When clearing the environment internally, preserve all variables starting with LD_. This is mostly for debugging purposes.
Print the version of the GDM daemon.
If started with this option, gdm will init, but only start the first local display and then wait for a GO message in the fifo protocol. No greeter will be shown until the GO message is sent. Also flexiserver requests will be denied and XDMCP will not be started until GO is given. This is useful for initialization scripts which wish to start X early, but where you don't yet want the user to start logging in. So the script would send the GO to the fifo once it is ready and GDM will then continue. This functionality was added in version 2.5.90.0.
gdmsetup runs a graphical application for modifying the GDM configuration file, gdm.conf. Normally on systems that support the PAM userhelper, this is setup such that when you run gdmsetup as an ordinary user, it will first ask you for your root password before starting. Otherwise, this application may only be run as root. This application supports standard GNOME options.
Specify an alternative configuration file. By default, gdmsetup will edit the same configuration file being used by the GDM daemon.
gdm-restart stops and restarts GDM by sending the GDM daemon a HUP signal. This command will immediately terminate all sessions and log out users currently logged in with GDM.