Process.waitFor() should be invoked after freeing up the input and error stream. While fixing https://issues.apache.org/jira/browse/HADOOP-2231 we found that this might be a possible cause.
Use exit code to detect normal errors while excuting 'ls' in Local FS
Remove usage of "bash -c" from oah.fs.DF
ShellCommand, in particular 'df -k', sometimes hang