Unexpected return from subscripts

[wangzhong . neu]

Hi all,

I'm not sure whether I should post this here. Sorry if disturb.

We met a very strange problem with bash "version 3.00.15(1)-release". We are 
using a hadoop-test script to test whether a file exists on HDFS. But we 
observed several times that the hadoop-test script, which is a subscript in a 
control-flow script, returned unexpectly. It seems the subscript was put in 
background, and the main-control script just go on and got a wrong return 
value. We added some debug log in the hadoop-test script, and it looks like 
this:

============== sh -x DEBUG LOG ==============
+ /home/work/hadoop-client/hadoop/bin/hadoop dfs -test -e xxxFile
+ '[' 0 -ne 0 ']'    # this is unexpected, the real return value is 1
+ some other things...
+ ...
+ ...
+ test: File does not exists: xxxFile    # this is unexpeted, should be printed 
before the condition statement. Looks like test script goes to background
+ ...
=============================================

This problem bothered us for several months because we have a large cluster 
with thousands of nodes running the hadoop-test script. We met this case every 
month. Anybody ever met the same problem?

Thanks,
Zhong