How can I wait for a USB Ethernet adapter to appear to configure lagg on startup?

[Masachika ISHIZUKA]

Hi.

I use a nootbook machine.
As this machine has no internal nic, I use a USB ethernet adapter(ue0).
I want to configure lagg0 of ue0 and iwm0, but I must wait to start
/etc/rc.d/netif until appearing the ue0.
I'm using patched netif as follows, but I must keep it whenever
'mergemaster -Ui' is run.
Is there a more elegant way?
-- 
Masachika ISHIZUKA
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netif_wait_timeout=60
netif_wait_if="ue0"