code: public int saveNamespace(String[] argv, int idx) throws IOException {
      int exitCode = -1;
  
      DistributedFileSystem dfs = getDFS();
      if (dfs == null) {
        System.err.println("FileSystem is " + getFS().getUri());
        return exitCode;
      }
  
      boolean force = false;
      boolean uncompressed = false;
      for( ; idx < argv.length; idx++) {
        if (argv[idx].equals("force")) {
          force = true;
        } else if (argv[idx].equals("uncompressed")) {
          uncompressed = true;
        } else {
          printUsage("saveNamespace");
          return exitCode;
        }
      }
      dfs.saveNamespace(force, uncompressed);
      return 0;
    }
docs: Command to ask the namenode to save the namespace.
  Usage: java DFSAdmin -saveNamespace [force] [uncompressed]
  
  @param argv List of of command line parameters.
  @param idx The index of the command that is being processed.
  @exception IOException