SDDM is the abbreviation of Simple Desktop Display Manager, which is a default display manager for LXQt and KDE Plasma.
It officially supports Linux and FreeBSD, but should also work well with other Unix-like system.
SDDM works under a special user in an UNIX-like system:
sddm. Its HOME directory is set to
If we want to install it ourselves, an
sddm user needs to be created, with its home set to
/var/lib/sddm by default.
In this directory, a
state.conf will be created. The content of it on my PC is:
which notes the latest login user and the correspond session. This will accelerate the next login.
The file is declared in
src/common/configuration.h and will be loaded later.
Like the other programs, SDDM also reads configuration from
/etc. The file is
/etc/sddm.conf, which contains several sections:
User icons are stored in
~/.face.icon (for each user).
Themes are stored in
$(DATADIR)/themes/. SDDM loads
Main.qml file in it to create an user interface.
Scripts to launch a specific session under an environment are stored in
$(DATADIR)/scripts/. These scripts will start the desktop environment.
For example, for X11, the configuration items are:
The script is
Xstop, etc. The desktop entries for desktop environments are placed in
In my case, the
plasma.desktop indicates the executable: