['__class__', '__delattr__', '__dict__', '__doc__', '__format__',
    '__getattribute__', '__getitem__', '__getslice__', '__hash__',
    '__init__', '__module__', '__new__', '__reduce__', '__reduce_ex__',
    '__repr__', '__setattr__', '__setstate__', '__sizeof__', '__str__',
    '__subclasshook__', '__unicode__', '__weakref__', 'args', 'cmd',
    'message', 'output', 'returncode']
check output from CalledProcessError