add sddm

technology/applications/Applications.md

@@ -38,6 +38,7 @@ rev: 2024-12-10
 
 ## Desktop
 - [KDE Plasma](./desktops/KDE%20Plasma.md)
+- [SDDM](./desktops/SDDM.md)
 - [dwm](./desktops/dwm.md)
 - [picom](./desktops/picom.md)
 - [Hyprland](./desktops/hyprland.md)

technology/applications/desktops/SDDM.md

@@ -0,0 +1,71 @@
+---
+obj: application
+arch-wiki: https://wiki.archlinux.org/title/SDDM
+wiki: https://en.wikipedia.org/wiki/Simple_Desktop_Display_Manager
+repo: https://github.com/sddm/sddm
+rev: 2024-12-17
+---
+
+# SDDM
+The Simple Desktop Display Manager (SDDM) is a display manager. It is the recommended display manager for the KDE Plasma and LXQt desktop environments. 
+
+## Configuration
+The default configuration file for SDDM can be found at `/usr/lib/sddm/sddm.conf.d/default.conf`. For any changes, create configuration file(s) in `/etc/sddm.conf.d/`.
+
+Everything should work out of the box, since Arch Linux uses systemd and SDDM defaults to using `systemd-logind` for session management.
+
+### Autologin
+SDDM supports automatic login through its configuration file, for example (`/etc/sddm.conf.d/autologin.conf`):
+
+```ini
+[Autologin]
+User=john
+Session=plasma
+
+# Optionally always relogin the user on logout
+Relogin=true
+```
+
+This configuration causes a KDE Plasma session to be started for user `john` when the system is booted. Available session types can be found in `/usr/share/xsessions/` for X and in `/usr/share/wayland-sessions/` for Wayland.
+
+To autologin into KDE Plasma while simultaneously locking the session (e.g. to allow autostarted apps to warm up), create a systemd user unit drop in to pass `--lockscreen` in `plasma-ksmserver.service` (`~/.config/systemd/user/plasma-ksmserver.service.d/override.conf`):
+
+```ini
+[Service]
+ExecStart=
+ExecStart=/usr/bin/ksmserver --lockscreen
+```
+
+### Theme settings
+Theme settings can be changed in the `[Theme]` section. If you use Plasma's system settings, themes may show previews.
+
+Set to `breeze` for the default Plasma theme.
+
+#### Current theme
+
+Set the current theme through the Current value, e.g. `Current=archlinux-simplyblack`.
+
+#### Editing themes
+The default SDDM theme directory is `/usr/share/sddm/themes/`. You can add your custom made themes to that directory under a separate subdirectory. Note that SDDM requires these subdirectory names to be the same as the theme names. Study the files installed to modify or create your own theme.
+
+#### Customizing a theme
+To override settings in the `theme.conf` configuration file, create a custom `theme.conf.user` file in the same directory. For example, to change the theme's background (`/usr/share/sddm/themes/name/theme.conf.user`):
+
+```ini
+[General]
+background=/path/to/background.png
+```
+
+#### Testing (previewing) a theme
+You can preview an SDDM theme if needed. This is especially helpful if you are not sure how the theme would look if selected or just edited a theme and want to see how it would look without logging out. You can run something like this:
+
+```sh
+sddm-greeter-qt6 --test-mode --theme /usr/share/sddm/themes/breeze
+```
+
+This should open a new window for every monitor you have connected and show a preview of the theme.
+
+#### Mouse cursor
+To set the mouse cursor theme, set `CursorTheme` to your preferred cursor theme.
+
+Valid Plasma mouse cursor theme names are `breeze_cursors`, `Breeze_Snow` and `breeze-dark`.