How to suspend from command line such that screen is locked?

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http://askubuntu.com – I'm using Xubuntu 12.04. In the Power Manager, I have checked Extended -> Lock screen when going for suspend/hibernate. If I choose to suspend from the main menu / Panel 1, the screen is locked. However, if I use dbus-send --system --print-reply --dest="org.freedesktop.UPower" /org/freedesktop/UPower org.freedesktop.UPower.Suspend (see How can I suspend/hibernate from command line?; I use this command via a keyboard shortcut), the screen is not locked. How can I (1) suspend the system (2) have the screen locked at the same time (3) do not require root rights to do so [since I would like the co (HowTos)