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From Allen Wittenauer ...@effectivemachines.com>
Subject Re: [VOTE] Merge HADOOP-13341
Date Fri, 09 Sep 2016 22:06:56 GMT

> On Sep 9, 2016, at 2:15 PM, Anu Engineer <aengineer@hortonworks.com> wrote:
> 
> +1, Thanks for the effort. It brings in a world of consistency to the hadoop vars; and
as usual reading your bash code was very educative.

	Thanks!

	There's still a handful of HDFS and MAPRED vars that begin with HADOOP, but those should
be trivial to knock out after a pattern has been established.

> I had a minor suggestion though. since we have classified the _OPTS to client and daemon
opts, for new people it is hard to know which of these subcommands are daemon vs. a client
command.  Maybe we can add a special char in the help message to indicate which are daemons
or just document it? Only way I know right now is to look the appropriate script and see if
HADOOP_SUBCMD_SUPPORTDAEMONIZATION is set to true.


	That's a great suggestion.  Would it be better if the usage output was more like:

---snip---
Usage: hdfs [OPTIONS] SUBCOMMAND [SUBCOMMAND OPTIONS]

  OPTIONS is none or any of:

--buildpaths                       attempt to add class files from build tree
--config dir                       Hadoop config directory
--daemon (start|status|stop)       operate on a daemon
--debug                            turn on shell script debug mode
--help                             usage information
--hostnames list[,of,host,names]   hosts to use in worker mode
--hosts filename                   list of hosts to use in worker mode
--loglevel level                   set the log4j level for this command
--workers                          turn on worker mode

  SUBCOMMAND is one of:


Clients:
	cacheadmin           configure the HDFS cache
	classpath            prints the class path needed to get the hadoop jar and the required
libraries
	crypto               configure HDFS encryption zones
	...

Daemons:
	balancer             run a cluster balancing utility
	datanode             run a DFS datanode
	namenode             run the DFS name node
...
---snip---

	We do something similar in Apache Yetus and shouldn't be too hard to do in Apache Hadoop.
We couldn't read SUPPORTDAEMONIZATION to place things, but as long as people put their new
commands in the correct section in hadoop_usage, it should work.


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