Run a command as a subprocess.
    Return a triple of return code, standard out, standard err.

def subp(cmd):
    """
    Run a command as a subprocess.
    Return a triple of return code, standard out, standard err.
    """
    proc = subprocess.Popen(cmd, stdout=subprocess.PIPE,
                            stderr=subprocess.PIPE)
    out, err = proc.communicate()
    return ReturnTuple(proc.returncode, stdout=out, stderr=err)