4.3. Virtual Consoles
As a multiprocessing system, Linux gives you a number of interesting ways to do several things at once. You can start a long software installation and then switch to reading mail or compiling a program simultaneously. This should be a major part of Linux's appeal to MS-DOS users (although the latest Microsoft Windows has finally come to grips with multiprocessing, too).
Most Linux users, when they want this asynchronous access, will employ the X Window System. But before you get X running, you can do something similar through virtual consoles. This feature appears on a few other versions of Unix, but is not universally available.
To try out virtual consoles, hold down the left Alt key and press one of the function keys, F1 through F8. As you press each function key, you see a totally new screen complete with a login prompt. You can log in to different virtual consoles just as if you were two different people, and you can switch between them to carry out different activities. You can even run a complete X session in each console. The X Window System will use the virtual console 7 by default. So if you start X and then switch to one of the text-based virtual consoles, you can go back again to X by typing Alt-F7. If you discover that the Alt + function key combination brings up an X menu or some other fuction instead of switching virtual consoles, use Ctrl + Alt + function key.
In earlier versions of Linux (until kernel 1.1.54), the number of available virtual consoles was fixed, but could be changed by patching, recompiling and reinstalling the kernel; the default was 8. Nowadays, the Linux kernel creates virtual consoles as needed on the fly. However, this does not mean that you can simply go to virtual console 13 and log in there. You can log in only on virtual consoles where a getty process is running (see the next chapter for more information on this).
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