mii-tool has the capability to watch a network interface for status changes.  It
is a simple enhancement to make it do something useful when it detects a status
change.  I will attach a short patch which adds a --script option; mii-tools
will call this script with the name of the changing interface and the string
"up" or "down" as arguments.

One such useful script is:

#!/bin/sh
/sbin/if$2 $1

This allows a laptop user to bring the network up just by plugging the cable in.
 Perhaps there is another way to do this, but I couldn't find it and this hack
was easy enough.

Beware, though, that my C is rusty, I haven't included a manpage patch, and this
is just a hack.  If this would be useful to others or might be included, I will
happily clean it up.