---
name: "gdm3"
section: "8"
platform: "linux"
package: "gdm3"
version: "48.0-2"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/gdm3"
---

# gdm3(8)

GNOME Display Manager

## NAME

gdm3 - GNOME Display Manager

## SYNOPSIS

gdm3

## DESCRIPTION

**gdm3** is the equivalent of [**xdm**(1x)](/xdm/1x.md) or [**wdm**(1x)](/wdm/1x.md), but uses the GNOME libraries to provide a GNOME look-and-feel. It provides the GNOME equivalent of a "login:" prompt.

**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*.

## ENVIRONMENT

- XAUTHORITY

  Upon session startup, GDM sets the XAUTHORITY environment variable to a session-specific file in */run/gdm3*.

  Applications and scripts that assume this file is set to *~/.Xauthority* will not work. To access the display you need both DISPLAY and XAUTHORITY variables.

## AUTHOR

Martin Kasper Petersen \<mkp@SunSITE.auc.dk\>

This manual page written by Steve Haslam \<araqnid@debian.org\> for Debian GNU/Linux. Updated by Raphaël Hertzog \<hertzog@debian.org\>, Ryan Murray \<rmurray@debian.org\>, Josselin Mouette \<joss@debian.org\> and  Vincent Lefevre \<vincent@vinc17.net\>.