[ubuntu-uk] Preventing shutdown on a remote machine

[Dan Fish]

Hi,

I've installed ubuntu on my dad's machine and he's very happy with it. 
I'm doing online backups from his computer to my machine with rsync 
initiated from my end. The only problem I'm having is that my dad has a 
habit of shutting down his machine before the (incremental) backup is 
complete. What I'd like to do is inhibit his ability to shutdown the 
machine during the backup and hopefully display a message to him 
explaining why.

Cheers
Dan