Ethernet card, cable link state ?

[Jonathan Andrews]

Sorry if this is off topic, but i've googled myself into a corner.

Whats the best way to check the cable link state for an ethernet
connection under core 3 ? I assumed that I would find something in /proc
- but so far nothing seems to toggle between cable connected and cable
disconnected.  eth0 is up.

Is the link state tracked for all eth devices, the linux device driver I
book implies it is.

Any pointers at docs would be very helpful at this point.

Cheers,
Jon