GNOME Display Manager (GDM) is a display manager (a graphical login manager) for the

windowing system In computing, a windowing system (or window system) is software that manages separately different parts of display screens. It is a type of graphical user interface (GUI) which implements the WIMP (windows, icons, menus, pointer) paradigm fo ...

X11 The X Window System (X11, or simply X) is a windowing system for bitmap displays, common on Unix-like operating systems. X provides the basic framework for a GUI environment: drawing and moving windows on the display device and interacting wi ...

and Wayland. The X Window System by default uses the XDM display manager. However, resolving XDM configuration issues typically involves editing a

configuration file In computing, configuration files (commonly known simply as config files) are files used to configure the parameters and initial settings for some computer programs. They are used for user applications, server processes and operating system ...

. GDM allows users to customize or troubleshoot settings without having to resort to a

command line A command-line interpreter or command-line processor uses a command-line interface (CLI) to receive commands from a user in the form of lines of text. This provides a means of setting parameters for the environment, invoking executables and pro ...

. Users can pick their session type on a per-login basis. GDM 2.38.0 is the last version that features customization with 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.

Components

GDM comprises the following components: * Chooser – a program used to select a remote host for managing a display remotely on the attached display (gdm-host-chooser) * Greeter – the graphical login window (provided by

GNOME Shell GNOME Shell is the graphical shell of the GNOME desktop environment starting with version 3, which was released on April 6, 2011. It provides basic functions like launching applications, switching between windows and is also a widget engine. ...

) *

Pluggable authentication module A pluggable authentication module (PAM) is a mechanism to integrate multiple low-level authentication schemes into a high-level application programming interface (API). PAM allows programs that rely on authentication to be written independently ...

(PAM) *

X Display Manager Control Protocol In the X Window System, an X display manager is a graphical login manager which starts a login session on an X server from the same or another computer. A display manager presents the user with a login screen. A session starts when a user ...

(XDMCP)

Hidden features

Until version 2.22, GDM had a few 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". * 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), 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. Subsequently, developers realised that the title " Queen of England" has not existed since the

Acts of Union of 1707 The Acts of Union ( gd, Achd an Aonaidh) were two Acts of Parliament: the Union with Scotland Act 1706 passed by the Parliament of England, and the Union with England Act 1707 passed by the Parliament of Scotland. They put into effect the te ...

References

External links