_checkAndAddBridge :: String -> String -> IO ()
_checkAndAddBridge bridge fwd_mask = do
    exists <- bridgeExists bridge
    case exists of
         False -> do debug $ "Adding bridge " ++ bridge
                     readProcessOrDie "ip" ["link", "add", bridge, "type", "bridge", "forward_delay", "0", "stp_state", "0", "group_fwd_mask", fwd_mask] []
                     return ()
         otherwise -> do debug $ bridge ++ "  already exists"
                         return ()
_checkAndAddBridge :: String -> String -> IO ()
_checkAndAddBridge bridge fwd_mask = do
    exists <- bridgeExists bridge
    case exists of
         False -> do debug $ "Adding bridge " ++ bridge
                     readProcessOrDie "ip" ["link", "add", bridge, "type", "bridge", "forward_delay", "0", "stp_state", "0", "group_fwd_mask", fwd_mask] []
                     return ()
         otherwise -> do debug $ bridge ++ "  already exists"
                         return ()
_checkAndAddBridge bridge fwd_mask = do
    exists <- bridgeExists bridge
    case exists of
         False -> do debug $ "Adding bridge " ++ bridge
                     readProcessOrDie "ip" ["link", "add", bridge, "type", "bridge", "forward_delay", "0", "stp_state", "0", "group_fwd_mask", fwd_mask] []
                     return ()
         otherwise -> do debug $ bridge ++ "  already exists"
                         return ()