path: acpi-support_0.143-5.2/debian/addons/lib/screenblank
    if [ "x$XAUTHORITY" != x ]; then
	export DISPLAY=:"$displaynum"
	if pidof xscreensaver >/dev/null; then
		su "$XUSER" -s /bin/sh -c "xscreensaver-command -throttle"
	fi