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Date: Thu, 31 Jan 2013 03:31:12 +0000 (UTC)
From: "Andrew Wang (JIRA)" <jira@apache.org>
To: common-issues@hadoop.apache.org
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Subject: [jira] [Created] (HADOOP-9267) hadoop -help, -h, --help should show
 usage instructions
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Andrew Wang created HADOOP-9267:
-----------------------------------

             Summary: hadoop -help, -h, --help should show usage instructions
                 Key: HADOOP-9267
                 URL: https://issues.apache.org/jira/browse/HADOOP-9267
             Project: Hadoop Common
          Issue Type: Bug
    Affects Versions: 3.0.0
            Reporter: Andrew Wang
            Assignee: Andrew Wang
            Priority: Minor


It's not friendly for new users when the command line scripts don't show usage instructions when passed the defacto Unix usage flags. Imagine this sequence of commands:

{noformat}
-> % hadoop --help
Error: No command named `--help' was found. Perhaps you meant `hadoop -help'
-> % hadoop -help
Error: No command named `-help' was found. Perhaps you meant `hadoop help'
-> % hadoop help
Exception in thread "main" java.lang.NoClassDefFoundError: help
Caused by: java.lang.ClassNotFoundException: help
	at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
Could not find the main class: help.  Program will exit.
{noformat}

Same applies for the `hdfs` script.

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