After I issue the shutdown command (ie. sudo shutdown -h +20) in an ssh session on another ubuntu machine on my LAN at home, I receive the "system will shutdown in 20 minutes" message and then can no longer type anything into the session, leaving me unable to logout.
When I searched the web for answers, I found one suggestion to try pressing ENTER then ~ (tilda) then . (period) to end the ssh session. It did, but I should be able to type after issuing the delayed shutdown command in an ssh session.