Start a new session:
screen -S session-name
Start a long-running foreground application:
while true; do echo $(date); sleep 2; done
Detach from the session:
ctrl-a + d
i.e. press ctrl-a, then press d.
List all running sessions:
screen -ls
Reattach to the session:
screen -dr session-name
To end the session, terminate the foreground application using ctrl-c, then type exit.