Screen

http://www.rackaid.com/resources/linux-screen-tutorial-and-how-to/

The screen package is part of Ubuntu.

To use it, log into a remote server with ssh and then type screen. This is just another terminal window running in the same SSH session.

See existing sessions:

[root@gigan root]# screen -ls
There are screens on:
        31619.ttyp2.gigan       (Detached)
        4731.ttyp2.gigan        (Detached)
2 Sockets in /tmp/screens/S-root.

Attach to existing session:

[root@gigan root]# screen -r 31619.ttyp2.gigan