sddm

sddm [OPTIONS]

-h, --help
    Shows help message and exits.

-v, --version
    Shows version information and exits.

-c <path>, --config <path>
    Specifies an alternative path to the configuration file, overriding the default.

SDDM (Simple Desktop Display Manager) is a display manager that handles graphical login for desktop environments on Linux and other Unix-like systems. It provides a user-friendly graphical interface (greeter) to authenticate users, allowing them to select their desktop environment (e.g., KDE Plasma, GNOME, XFCE) and language before logging in. SDDM supports both X11 and Wayland display servers, making it a versatile choice for modern Linux distributions. It is highly configurable through its sddm.conf file, allowing customization of themes, sessions, and various display settings. It's typically started automatically at boot time by the system's init system (like systemd) and manages multiple user sessions. Its primary role is to start and manage display servers and user sessions after authentication, ensuring a seamless transition from boot to a usable graphical desktop.

sddm is primarily a system daemon managed by the init system (e.g., systemd) and is not typically run directly by users from the command line for daily operation. Most of its behavior and appearance are controlled through its configuration files, particularly /etc/sddm.conf, rather than command-line options. Troubleshooting often involves examining system logs via journalctl.

SDDM's primary configuration is managed through its configuration file, typically located at /etc/sddm.conf or modularly within /etc/sddm.conf.d/. This file allows administrators to customize themes, default sessions, X11 and Wayland specific settings, user session behaviors, and security policies.

SDDM supports rich theming using QML, providing a highly customizable login interface (greeter). Users can choose different themes to change the look and feel of their login screen. The default greeter is usually sddm-greeter, which manages the actual graphical login process and user interaction.

SDDM was created as a modern, QML-based display manager to offer an alternative to older options like GDM and LightDM. Its development prioritized flexibility, extensive theming capabilities, and robust support for newer display technologies, including Wayland. It gained significant traction, especially within the KDE community, and has become the default display manager for KDE Plasma in many popular Linux distributions, emphasizing a lightweight and visually appealing login experience.

gdm(1), lightdm(1), xdm(1), display-manager(7), systemd-logind(8), sddm.conf(5)