[HADOOP-10927] Fix CredentialShell help behavior and error codes

• Type: Bug
• Status: Closed
• Priority: Minor
• Resolution: Fixed
• Fix Version/s: 2.6.0
• Component/s: security
• Target Version/s: 2.6.0
• Assignee: Josh Elser
• Reporter: Josh Elser
• Created: 01/Aug/14 23:43
• Updated: 01/Dec/14 03:10
• Resolved: 05/Aug/14 00:26

Description

$ hadoop credential
java.lang.NullPointerException
	at org.apache.hadoop.security.alias.CredentialShell.run(CredentialShell.java:67)
	at org.apache.hadoop.util.ToolRunner.run(ToolRunner.java:70)
	at org.apache.hadoop.security.alias.CredentialShell.main(CredentialShell.java:420)

Ran a no-arg version of hadoop credential expecting to get the usage/help message (like other commands act), and got the above exception instead.