Screen Multi-user Mode

Suppose Bob wants to show Alice what he’s doing in his console remotely. Bob would do the following:

1. Bob would make sure that the screen binary is suid root (sudo chmod +s /usr/bin/screen on my system).

2. Bob starts screen:
screen -S <session_name>

3. Bob allows multiuser access:
^A :multiuser on

4. Bob adds Alice to the access control list:
^A :acladd alice

5. Bob then changes Alice’s permissions to read-only:
^A :aclchg alice -w "#"

6. Alice will then ssh into the machine and:
screen -x bob/<session_name>

That’s awesome.

Notes:

• People can join your session even if you skip acladd and just do aclchg, but they won’t be able to detatch. Weird.
• ^A * lists all participating users (as does ^A :displays)
• Anybody in the session can broadcast a message by typing ^A :wall <message_text>