Desktop startup sequence

#The start script

The startup sequence begins with startplasma-x11, which the login manager normally calls once you've been authenticated. It sets up the environment, including running your session environment scripts, and then hands control to plasma_session.

plasma_session starts the desktop's core in order:

1. kcminit_startup runs the initialization services.
2. kded6 starts the background services.
3. The window manager starts. This is SonicWin, unless KDEWM is set.
4. ksmserver, the session manager, starts.
5. The desktop shell and autostart applications follow.

#Background services

All these background services are specific to a user. Unlike system daemons, they aren't shared between users.

#dbus-daemon: inter-process communication

dbus-daemon provides inter-process communication to applications as well as several other system components, such as NetworkManager, power management and applications from other desktops. It's a portable, cross-desktop project hosted at freedesktop.org. SonicDE is also gradually moving some of its communication to its own framework, sonic-frameworks-ipc.

D-Bus services can be reached from the shell with the qdbus6 command-line tool.

#kded6: background services

kded6 is a generic daemon that loads various service modules and runs them in the background. The Background Services module in System Settings shows the status of these modules and can disable some of them.

#kcminit: initialization services

kcminit runs initialization services during startup. Modules declare them with the X-KDE-Init line. They're typically used to initialize hardware based on your settings.

kcminit --list shows all the initialization services, and kcminit <service> runs a single one. This can be useful when investigating startup problems.

#ksmserver: session management

ksmserver is the session manager, which determines the lifetime of the session. It restores applications from the previous session.

The session manager restores one of the previous sessions. A session is a collection of applications, along with application-specific information that reflects their state when the session was saved. Sessions are stored in the ksmserverrc configuration file, with references to each application's state information.

For example, ksmserverrc may contain lines like these, and the application-specific information is stored in files named after each of these identifiers:

restartCommand1=kwin_x11,-session,110a0a0002000106760689100000019360000_1083342151_608625
restartCommand2=konsole,-session,10378ac070000108334204700000277690000_1083342151_552722

The state information of the window manager contains the location of the windows of all the other applications in the session.

#Autostart

Applications to start automatically are given by .desktop files in the autostart folder of your configuration directories. The Autostart module manages these.

A .desktop file can make its start conditional with the X-KDE-autostart-condition entry:

X-KDE-autostart-condition=ktiprc:TipOfDay:RunOnStart:true

This means the ktiprc configuration file is checked for a RunOnStart entry in the [TipOfDay] group. If there is no such entry, true is assumed, so the application starts by default.

#Desktop components

The main components of the desktop are the window manager, the command runner and the workspace, which is the desktop and its panels.

#SonicWin: window manager

The window manager is responsible for managing all the windows across the virtual desktops, including their initial placement, minimizing, maximizing, raising, lowering and switching focus between them.

By default, SonicWin is started as the window manager. To override this, set the KDEWM environment variable to the name of another window manager.

#KRunner: run dialog

KRunner provides the Alt+F2 search and run dialog.

#sonicshell: desktop and panels

sonicshell provides the desktop and panels. See Restarting the shell.