Syntax:

waitfor name

Use the waitfor command to request a notification when a certain player logs in. Let's say you type:

waitfor marvin

and marvin logs in. You'll see a message saying:

** FINALLY!!! marvin logs in

and marvin will see a message saying:

<your_name> is waiting for you to log in.

You can wait for more than one player at a time. There is no way to stop waiting for a player unless that player logs in or you log out.

Type waitfor without a name to see a list of players you are waiting for.