This entire method, and everywhere it's called, should probably be replaced by [`subprocess.check_call()`](https://docs.python.org/2.6/library/subprocess.html#subprocess.check_call), which does almost the same thing but also will fire an exception if the return code is non-zero. If you want to ignore this, use `subprocess.call()`. I'd probably want to raise the exception, but I'm not familiar with how likely failure is with these tools.