Get the OSX system ID.
    $ system_profiler |grep "r (system)"
    Serial Number (system): C24E1322XYZ

def get_osx_system_uid():
    """Get the OSX system ID.
    $ system_profiler |grep "r (system)"
    Serial Number (system): C24E1322XYZ
    """
    res = backtick(["system_profile"]).splitlines()
    for line in res:
        if "r (system)" in line:
            return line.split(':', 1)[1].strip()
    raise ValueError("Could not find system number in %r" % res)