Suppose a non-root user with sudo privileges executes a delayed shutdown (`shutdown +10` or whatever) and logs out. Then, before the shutdown occurs, he wants to log back in and cancel the shutdown. The problem is that `shutdown` creates `/etc/nologin`, and `login` only allows root to log in when that file exists... is it possible to create an exception from this for a user?

If not, what would be the best way to let a user initiate a delayed shutdown, then logging in and cancelling it at a later point?