Editing GNOME Display Manager

{{Short description|Display manager for the windowing systems X11 and Wayland}}
{{Use dmy dates|date=September 2022}}
{{Infobox software
| name = GNOME
| title = GNOME Display Manager
| logo = 
| screenshot = File:GNOME Display Manager in GNOME 47, RHEL 10.png
| caption = GNOME Display Manager 47 (its default appearance uses a [[dark theme]])
| author = 
| developer = [[The GNOME Project]] (William Jon McCann, Brian Cameron, Ray Strode)
| latest release version = {{wikidata|property|edit|reference|Q1460961|P548=Q2804309|P348}}
| latest release date = {{start date and age|{{wikidata|qualifier|Q1460961|P548=Q2804309|P348|P577}}}}
| latest preview version = {{wikidata|property|edit|reference|Q1460961|P548=Q51930650|P348}}
| latest preview date = {{start date and age|{{wikidata|qualifier|Q1460961|P548=Q51930650|P348|P577}}}}
| programming_language = [[C (programming language)|C]]
| operating_system = [[Unix]] and [[Unix-like]] ([[Linux]], [[BSD]], [[Solaris (operating system)|Solaris]])
| genre = [[Login manager]] for [[Wayland (display server protocol)|Wayland]], [[X display manager]]
| license = [[GNU General Public License|GPL-2.0-or-later]]
}}

'''GNOME Display Manager''' ('''GDM''') is a [[X display manager|display manager]] (a graphical [[login manager]]) for the [[windowing system]]s [[X11]] and [[Wayland (display server protocol)|Wayland]].

The X Window System by default uses the [[XDM (display manager)|XDM]] display manager. However, resolving XDM configuration issues typically involves editing a [[configuration file]]. GDM allows users to customize or troubleshoot settings without having to resort to a [[Command-line interface|command line]]. Users can pick their [[Login session|session]] type on a per-login basis. GDM 2.38.0 is the last version that features customization with [[Skin (computing)|themes]]; subsequent releases do not support themes.

==Software architecture==
GDM is a display manager that implements all significant features required for managing attached and remote displays. GDM was written from scratch and does not contain any XDM or X Consortium code.<ref>{{cite web
 | url   = https://help.gnome.org/admin/gdm/
 | title = GDM documentation}}</ref>

===Components===
GDM comprises the following components:
* Chooser – a program used to select a remote host as the source for a remote display on the attached display (gdm-host-chooser)
* Greeter – the graphical login window (provided by [[GNOME Shell]])
* [[Pluggable authentication module]] (PAM)
* [[X Display Manager Control Protocol]] (XDMCP)

==Hidden features==
Until version 2.22,<ref>{{cite web
 | url        = http://git.gnome.org/browse/gdm/commit/gui/gdmlogin.c?h=gnome-2-22&id=3dfd5dedf50bb4a95730dea046aedcfec678fca1
 | title      = migrate gui to new config framework with a chainsaw
 | date       = 2007-06-01
 | access-date = 2014-04-26}}</ref> GDM had a few [[Easter egg (media)|Easter eggs]], in the form of strings to be entered in the username box. These can be found in the source file "gui/guilogin.c", in a function named "evil".<ref>{{cite web
 | archive-url = https://gitlab.gnome.org/GNOME/gdm/blob/gnome-2-20/gui/gdmlogin.c#L807
 | url         = http://git.gnome.org/cgit/gdm/tree/gui/gdmlogin.c?h=gnome-2-20#n806
 | title       = gdm – guilogin.c
 | archive-date = 2018-05-31
 | access-date  = 2018-08-09}}</ref>

* Dancing login – type "Start Dancing" to start, and "Stop Dancing" to stop.
** (This requires the standard greeter ("GTK+ Greeter"), rather than the graphical one ("Themed Greeter")).
* "Gimme Random Cursor" – can be used repeatedly.
** This changes the mouse cursor to a randomly selected 1 of 77 different "cursor fonts" as defined in the X11 specification.
* "Require Quarter" (or "Require Quater", for backward compatibility with a typo in the original),<ref>{{cite web
 | url        = http://git.gnome.org/cgit/gdm/commit/?h=gnome-2-20&id=ee8de912c84d9df4180965fe49108051f563ce11 | title= GDM commit ee8de912
 | date       = 5 March 2001
 | access-date = 2009-08-26}}</ref> then log in normally – a dialog box that reads "Please insert 25 cents to log in." appears after entering the password. Clicking "OK" allows the login process to proceed as normal.

===Queen of England===
Some of the copyright notices of GDM refer to the "Queen of England", whom release announcements from version 2.2.1 also named as a maintainer.<ref>{{cite web
 | url   = https://mail.gnome.org/archives/gnome-announce-list/2001-May/msg00008.html
 | title = ANNOUNCE: GDM 2.2.1, the 'Just because you're not paranoid doesn't mean they're not after you' release
 | date  = 4 May 2001
 | quote = Gdm2 was originally written by Martin K. Petersen <mkp mkp net>, and is now maintained by the Queen of England.}}</ref> Subsequently, developers realised that the title "[[List of English monarchs|Queen of England]]" has not existed since the [[Acts of Union 1707|Acts of Union of 1707]].<ref>{{cite web
 | url   = https://mail.gnome.org/archives/gdm-list/2004-March/msg00002.html
 | title = ANNOUNCE: GDM 2.5.90.2 (unstable), the "Nose poking" release
 | date  = 4 March 2004}}</ref>

==See also==
{{Portal|Free and open-source software}}
# [[getty (Unix)|getty]] – a non-graphical login program
# [[LightDM]]
# [[Simple Desktop Display Manager|SDDM]] ([[KDE Plasma 5]] and [[KDE Plasma 6]])
# [[KDE Display Manager]] ([[KDE Plasma 4]])

==References==
{{Reflist}}

==External links==
{{Commons category}}
* {{Official website}}

{{GNOME}}
{{XWinSys}}
[[Category:GNOME]]
[[Category:X display managers]]