The Linux kernel supports virtual consoles. These provide a way of
making your single screen and keyboard seem like multiple terminals that are
connected to the same system. Thankfully, using virtual consoles is one of the
simplest things about Debian: There are ``hot keys'' for switching among the
consoles quickly. To try it, log in to your system and press Alt-F2
(simultaneously press the left Alt key, and F2, that is, function
key number 2).
You should find yourself at another login prompt. Don't panic: You are now on
virtual console (VC) number 2! Log in here and do some things - more whoami
commands or whatever - to confirm that this is a real login shell. Now you
can return to virtual console number 1 by pressing Alt-F1. Or you can
move on to a third virtual console, in the obvious way (Alt-F3).
Debian comes with six virtual consoles enabled by default, which you access
with the Alt key and function keys F1 through F6.
(Technically, there are more virtual consoles enabled, but only six of them
allow you to log in. The others are used for the X Window system or other special
purposes.)
If you're using the X Window system, it will generally start up on the first
unused virtual console - probably VC 7. Also, to switch from the X virtual
console to one of the first six, you'll have to add Ctrl to the key
sequence. So that's Ctrl-Alt-F1 to get to VC 1. But you can go from
a text VC to the X virtual console using only Alt. If you never leave
X, you won't have to worry about this; X automatically switches you to its virtual
console when it starts up.
Once you get used to them, virtual consoles will probably become an indispensable
tool for getting many things done at once. (The X Window system serves much
the same purpose, providing multiple windows rather than multiple consoles.)
You can run a different program on each VC or log on as root on one VC and as
yourself on another. Or everyone in the family can use his or her own VC; this
is especially handy if you use X, in which case you can run several X sessions
at once on different virtual consoles.