code: private static void printUsage(String cmd) {
      if ("-refreshServiceAcl".equals(cmd)) {
        System.err.println("Usage: java MRAdmin" + " [-refreshServiceAcl]");
      } else if ("-refreshQueueAcls".equals(cmd)) {
        System.err.println("Usage: java MRAdmin" + " [-refreshQueueAcls]");
      } else if ("-refreshNodes".equals(cmd)) {
        System.err.println("Usage: java MRAdmin" + " [-refreshNodes]");
      } else {
        System.err.println("Usage: java MRAdmin");
        System.err.println("           [-refreshServiceAcl]");
        System.err.println("           [-refreshQueueAcls]");
        System.err.println("           [-refreshNodes]");
        System.err.println("           [-help [cmd]]");
        System.err.println();
        ToolRunner.printGenericCommandUsage(System.err);
      }
    }
docs: Displays format of commands.
  @param cmd The command that is being executed.