I just needed to add additional ip addresses onto a network interface and wanted to do this without rebooting the server. I found the best way was just to bring the interface up and down:
sudo ifdown -a
Then bring the interface backup.
sudo ifup -a
Gee whiz. That’s really not very helpful unless you’re sitting at the local console.
Okay. Just to be clear – you have to open a terminal for this one.