User userA and userB want to share a single screen session and see what the other user is typing. This is very handy for some showcases.
- UserA starts a new screen session with screen -S shared
- Then userA allows other users to connect to the shell with CTRL-A and :multiuser on
- Last userA has to allow the other user to connect with CTRL-A and :acladd userB
- userB connects to server and connects to A’s session with screen -x userA/shared
Note: Eventually you have to add the suid bit to screen with chmod +s /usr/bin/screen. This could be a security hole. So better share user’s screens and not root ones 😉