sudo vi /etc/init.d/gdm
stop)
log_begin_msg "Stopping GNOME Display Manager..."
start-stop-daemon --stop --quiet --oknodo --pidfile $PIDFILE --name gdm $SSD_ARG --retry 30 >/dev/null 2>&1
# yfang add one line to clean two dirs
rm -rf /home/yfang/.config/gnome-session /home/yfang/.config/session-state 2>/dev/null
log_end_msg 0