code: public static boolean isServiceSpecified(String command, Configuration conf,
        String[] argv) {
      if (conf.get(FSConstants.DFS_FEDERATION_NAMESERVICES) != null) {
        for (int i = 0; i < argv.length; i++) {
          if (argv[i].equals("-service")) {
            // found service specs
            return true;
          }
        }
        // no service specs
        printServiceErrorMessage(command, conf);
        return false;
      }
      return true;
    }
docs: Checks if the service argument is specified in the command arguments.