gdm3 reads /etc/gdm3/daemon.conf for its configuration. For each local display, gdm starts an X server and runs a minimal GNOME session including a graphical greeter. If configured so, the main gdm process also listens for XDMCP requests from remote displays. These requests can either be direct, causing gdm3 to start a session on the remote display, or indirect, causing a chooser to be opened.
When managing a display, gdm3 attempts to execute /etc/gdm3/Init/display, or /etc/gdm3/Init/Default if that does not exist. When a user logs in, gdm3 first attempts /etc/gdm3/PreSession/display (or /etc/gdm3/PreSession/Default), and then one of the sessions defined in /usr/share/xsessions. When the session has completed, gdm attempts to run /etc/gdm3/PostSession/display, or /etc/gdm3/PostSession/Default.
gdm3 maintains information about the displays it is managing in /var/lib/gdm3. This includes xauth information, so this directory is not readable to normal users.
gdm3 uses PAM to perform authentication using the config file /etc/pam.d/gdm3.
This manual page written by Steve Haslam <araqnid@debian.org> for Debian GNU/Linux. Updated by RaphaA~Xl Hertzog <hertzog@debian.org>, Ryan Murray <rmurray@debian.org> and Josselin Mouette <joss@debian.org>.