[erlang-questions] os:cmd

[eigenfunction]

I am using rsync through os:cmd and rely on the console ouput from the
rsync command to decide whether or not the operation was successulf or
not, specially in the case where a file is missing on the remote end.
What i found out is that the return value of os:cmd does not always
equal the output of the rsync command run in the console.
Therefore my question: Is it the normal behaviour?