network disconect msg

[jackjill]

hi all,
i am trying to make a shell script .i.e.
if the pc is disconnected from the network , make a
msg appear in 20 sec, stating that website is not
available and ask the user to try again later. when
the network is reconnected, the system should return
to the browser.

that's it.
please tell me how to solve this prob.

thankx in advance