apache/hadoop · error · UnknownCommandException

`" + cmd + "': Unknown command

Error message

`" + cmd + "': Unknown command

What it means

Error "`" + cmd + "': Unknown command" thrown in apache/hadoop.

Source

Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsShell.java:217

    printInfo(out, cmd, false);
  }

  // print all helps
  private void printHelp(PrintStream out) {
    printInfo(out, null, true);
  }

  // print one help
  private void printHelp(PrintStream out, String cmd) {
    printInfo(out, cmd, true);
  }

  private void printInfo(PrintStream out, String cmd, boolean showHelp) {
    if (cmd != null) {
      // display help or usage for one command
      Command instance = commandFactory.getInstance("-" + cmd);
      if (instance == null) {
        throw new UnknownCommandException(cmd);
      }
      if (showHelp) {
        printInstanceHelp(out, instance);
      } else {
        printInstanceUsage(out, instance);
      }
    } else {
      // display help or usage for all commands 
      out.println(getUsagePrefix());
      
      // display list of short usages
      ArrayList<Command> instances = new ArrayList<Command>();
      for (String name : commandFactory.getNames()) {
        Command instance = commandFactory.getInstance(name);
        if (!instance.isDeprecated()) {
          out.println("\t[" + instance.getUsage() + "]");
          instances.add(instance);
        }

View on GitHub (pinned to 2add963021)

Solutions

1. Run 'hadoop fs -help' to list supported commands and fix the command name.
2. Check for typos in the command passed to FsShell.

When it happens

Trigger: Thrown at hadoop-common-project/hadoop-common/src/main/java/org/apache/hadoop/fs/FsShell.java:217 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of apache/hadoop@2add963021 (2026-08-22). Data as JSON: /api/errors/bac7af6a361df63e. Report an issue: GitHub.