When you`re rebooting a computer, and you need to know exactly when it is back online, try using this command:
ping -t <target>
<target> can be an IP or domain name.
This command will keep pinging the machine endlessly, which can reveal exactly when the computer is back on the network. As long as you keep getting “Request time out”, the machine isn’t online yet. When you get a reply, as illustrated below, you know you can connect to the machine.
Personally, I tend to put this window on my secondary monitor, while I continue working on the primary monitor. As soon as the machine is online, I close the window or press CTRL+C to prevent the ping from going on endlessly. Be careful how you use this – some hosts can interpret endless pinging as an attack.
Thanks to François Deschênes for originally showing me this trick.