"dcop ksmserver default logout"
followed by three parameters, the parameters mean:
First parameter: confirm
Obey the user's confirmation setting: -1
Don't confirm, shutdown without asking: 0
Always confirm, ask even if the user turned it off: 1
Second parameter: type
Select previous action or the default if it's the first time: -1
Only log out: 0
Log out and reboot the machine: 1
Log out and halt the machine: 2
Third parameter: mode
Select previous mode or the default if it's the first time: -1
Schedule a shutdown (halt or reboot) for the time all active sessions
have exited: 0
Shut down, if no sessions are active. Otherwise do nothing: 1
Force shutdown. Kill any possibly active sessions: 2
Pop up a dialog asking the user what to do if sessions are still active: 3
Example:
dcop ksmserver default logout 0 -1 -1
I can't test this on trinity but it worked in an old kde3 vm