Ubuntu Trusty userspace command to put system to suspend

 
Below is the Ubuntu Trusty userspace command to put system to suspend.

dbus-send --system --print-reply --dest="org.freedesktop.UPower" /org/freedesktop/UPower org.freedesktop.UPower.Suspend

Put the above command into the keyboard shortcut can immediately put your desktop to sleep upon entering the shortcut key.