code: public static void main(String[] args) throws IOException {
      if (!parseInputArgs(args)) {
        usage();
        System.exit(EXIT_FAILED);
      }
      if (sHelp) {
        usage();
        System.exit(EXIT_SUCCEEDED);
      }
      if (!sNoTimeout && !stdinHasData()) {
        System.exit(EXIT_FAILED);
      }
  
      JournalFormatter formatter = new ProtoBufJournalFormatter();
      try (JournalInputStream journalStream = formatter.deserialize(System.in)) {
        JournalEntry entry;
        while ((entry = journalStream.read()) != null) {
          System.out.print(entry);
          System.out.println(ENTRY_SEPARATOR);
        }
      }
    }
docs: Reads a journal via
  {@code java -cp \
  assembly/server/target/alluxio-assembly-server-<ALLUXIO-VERSION>-jar-with-dependencies.jar \
  alluxio.master.journal.JournalTool < journal/FileSystemMaster/log.out}.
  
  @param args arguments passed to the tool