The /etc/kde4/kdm/Xreset script is a script that runs as root after a user's X session exits. It can be used to perform some cleanup tasks or other actions that need to be done when the user logs out of the graphical environment. For example, it can reassign the ownership of the console to root, or shut down the system if desired. The /etc/kde4/kdm/Xreset script is part of the KDE Display Manager (kdm), which is a graphical login manager for X. KDM can be configured to run this script by setting the Reset key in the [X-*-Core] section of the /etc/kde4/kdm/kdmrc configuration file.Reference:

kdm.options - configuration options for X display manager

kdm(1) --- kdm --- Debian jessie --- Debian Manpages

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