Screen: multiple-window session manager with detach/re-attach.

GNU screen is something every UNIX user should have in his/her toolbox for everyday work.

It is a utility that allow for multiple text consoles on a single terminal (be it xterm,
iTerm or a physical console) with:

• cut & paste between all of them

• independant scrollable history

• dynamic creation/destruction of consoles

but there is more (and where the real value of screen is):

• you can detach and re-attach at any time.

That means that you can have long-time running tasks in separate consoles (like ssh on a remmote machine, IRC sessions, …)
on a given machine, detach from the session, move from one physical location to another, connect to the machine through ssh and
re-attach to the screen session to keep on working. No need to re-login, re-connect or anything.

That’s brilliant.

More information here

UPDATE:

Following some discussions on the FreeBSD mailing-lists, something came to my attention: tmux is a clone of GNU screen, using the BSD license. It seems to be a bit more than just a rewrite and its design seems a bit cleaner than GNU screen. It is, for some unknown reason, located in the misc category in /usr/ports (whereas GNU screen is in the more proper sysutils one).

The main site for tmux is on Sourceforge.net.

Be sure to check it out, I will.