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From S D <sd.codewarr...@gmail.com>
Subject Can anyone verify Hadoop FS shell command return codes?
Date Mon, 23 Feb 2009 13:02:22 GMT
I'm attempting to use Hadoop FS shell (http://hadoop
.apache.org/core/docs/current/hdfs_shell.html) within a ruby script. My
challenge is that I'm unable to get the function return value of the
commands I'm invoking. As an example, I try to run get as follows

hadoop fs -get /user/hadoop/testFile.txt .

>From the command line this generally works but I need to be able to verify
that it is working during execution in my ruby script. The command should
return 0 on success and -1 on error. Based on

http://pasadenarb.com/2007/03/ruby-shell-commands.html

I am using backticks to make the hadoop call and get the return value. Here
is a dialogue within irb (Ruby's interactive shell) in which the command was
not successful:

irb(main):001:0> `hadoop dfs -get testFile.txt .`
get: null
=> ""

and a dialogue within irb in which the command was successful

irb(main):010:0> `hadoop dfs -get testFile.txt .`
=> ""

In both cases, neither a 0 nor a 1 appeared as a return value; indeed
nothing was returned. Can anyone who is using the FS command shell return
values within any scripting language (Ruby, PHP, Perl, ...) please confirm
that it is working as expected or send an example snippet?

Thanks,
John

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