ZSH: Add user shutdown functions

These functions overwrite the executables reboot and shutdown

.zshrc

@@ -32,6 +32,22 @@ function line()
     echo " $1"
 }
 
+function shutdown()
+{
+    dbus-send --system --print-reply \
+        --dest="org.freedesktop.ConsoleKit" \
+        /org/freedesktop/ConsoleKit/Manager \
+        org.freedesktop.ConsoleKit.Manager.Stop
+}
+
+function reboot()
+{
+    dbus-send --system --print-reply \
+        --dest="org.freedesktop.ConsoleKit" \
+        /org/freedesktop/ConsoleKit/Manager \
+        org.freedesktop.ConsoleKit.Manager.Restart
+}
+
 # Initialize colors.
 autoload -U colors
 colors