LightDM

LightDM is a display manager for Linux and Unix-like systems. It provides the graphical login screen, handles user authentication, and starts user sessions. LightDM is designed to be lightweight, fast, and portable across desktop environments, serving as a common interface between the display server and user sessions.

LightDM uses a modular greeter system, where the login UI is implemented by separate greeter programs. A greeter presents the login prompt and can vary in look and feel; examples include GTK+ based greeters, WebKit2-based greeters, and other desktop-specific variants. The core LightDM server manages seats, authentication, and the launching of user sessions, and it can integrate with PAM and systemd-logind to coordinate with the system’s authentication and session management.

Configuration and operation are largely driven by text files. The main configuration file is typically /etc/lightdm/lightdm.conf, with sections that control seating, greeter selection, and session behavior. Greeter-specific options may be placed in greeter configuration files. LightDM also exposes options for debugging and can be controlled or queried via D-Bus.

LightDM is free and open-source software. It has been used as the default or widely adopted display manager in several Linux distributions, and it remains maintained by the LightDM project and its community of contributors. Its extensible greeter system and lightweight footprint have contributed to its continued relevance for users seeking a simple, modular login experience.

See also: other display managers such as GDM and SDDM.