'screen' is a terminal multiplexer, which lets you run multiple virtual terminal screen-windows in a single window-manager-window (e.g. an X11 xterm or a Mac Terminal window). You can also put your screen session into multiple window-manager-windows, disconnect from them, and reconnect to them later, e.g. on a remote server you can run a screen session, disconnect, log out, log back in from somewhere else, and reconnect, with no disruption whatsoever to the terminals within your session.

= .screenrc =

Your .screenrc file configures how screen works. Settings that JBS likes:

{{{
escape ^\^\ 
hardstatus off 
hardstatus string '[BBN screen %n%? (%t%?)] %h' 
startup_message off 
term vt100 
vbell off 
bind \\ 
bind ^h prev 
}}}

The first in particular is very handy, substituting Ctrl-\ as the screen escape character, which is helpful if you like to use Emacs (or any other program that uses Ctrl-A to do something useful). Check the man page for more info about the others, or ask JBS.

= Using screen as a serial terminal =

Aside from the usual awesome things you can do with screen, you can also use it as a serial terminal, like 'tip' or 'cua'.

To start up a screen session that way, on Ubuntu, do
{{{
screen /dev/ttyS0
}}}
(or replace /dev/ttyS0 with whatever your serial terminal device is, if you're not running Ubuntu).

To open a new serial terminal window in an existing screen session, do
{{{
Ctrl-\ : screen /dev/ttyS0
}}}
(assuming you've set Ctrl-\ as your escape character; and that /dev/ttyS0 is your serial device).