Save session using shell command in KDE

This one's easy.

Go to System Settings > Input Actions. In the selection area, do right click > New Global Shortcut > Command/URL. Make sure you give it a name, a shortcut, a command, and tick the Enabled box. Click Apply and you're done.

Coincidentally, though, the the "Examples" group should already contain an action named "Run Console," activated by Ctrl+Alt+T. Note that you'll need to enable shortcuts for the parent "Examples" group before you can enable "Run Console."

You can send a logout command via dbus to KDE, which should (if it can) terminate the session.

qdbus org.kde.ksmserver /KSMServer logout 0 0 0

dbus is a messaging system that lets applications communicate with each other, and the qdbus command is a utility for sending dbus messages to applications.

Applications register with dbus, and the ksmserver part of KDE is the session manager - it looks after who is logged in.

So we are sending a message to ksmserver to the /KSMServer interface and telling it to logout. The message we are sending is the exact same message that is sent to KSM when you click on the logout icon on your desktop.

The three zeros are parameters and can alter the type of logout we are doing:

First parameter:

• 0 = Do not wait for confirmation
• 1 = Wait for confirmation (with a 30 second timeout)

Second parameter:

• -1 = Prompt for action, defaulting to shutdown (Only makes sense when waiting for confirmation.)
• 0 = Logout
• 1 = Restart
• 2 = Shutdown

The third parameter is the "when" parameter, but it isn't clear what its impact is.