"GNU Screen is one of the most useful utilities for any admin,
but what if Screen isn't your cup of tea? For the longest time, GNU
Screen was the only game in town -- but the up-and-coming tmux is
worth checking out.
"What's tmux? Like Screen, it's a "terminal multiplexer," which
is a fancy way of saying you can run multiple sessions in the same
terminal (and then some). Like Screen, tmux does much more than
just let you manage "windows" (or, you know, screens if you prefer)
running pseudo terminals.
"How does tmux differ from Screen? Aside from licensing (GNU
Screen is GPL'ed, tmux is BSD licensed), which is a big hairball
that I won't get into, tmux offers a few features that Screen does