sS linux_switchToExternalMonitor_1() {
  S external = linux_getExternalMonitorID();
  if (external == null) ret "No external monitor";
  S internal = linux_getInternalMonitorID();
  if (internal == null) ret "Unknown internal monitor ID";
  ret backtick_verbose("xrandr --output " + external + " --auto --output " + internal + " --off");
}