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 for ...

s X11 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 (PAM) * X Display Manager Control Protocol (XDMCP)

Hidden features

Until version 2.22, GDM had a few

Easter eggs Easter eggs, also called Paschal eggs, are eggs that are decorated for the Christian feast of Easter, which celebrates the resurrection of Jesus. As such, Easter eggs are common during the season of Eastertide (Easter season). The oldest tra ...

, 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 The monarchy of the United Kingdom, commonly referred to as the British monarchy, is the constitutional form of government by which a hereditary sovereign reigns as the head of state of the United Kingdom, the Crown Dependencies (the Bailiw ...

" has not existed since the Acts of Union of 1707.

References

External links