Logoff or Shutdown Linux
at the command prompt exits your current user account and returns you to the log-in prompt. (The exit command does the same thing as logout.) To log out from multiple consoles, use alt-Fn to switch between consoles and then log out from each one. But note that even if you log out from all of your active consoles, Linux is still running.
If you were to power off your machine at this point, a voice from your computer would drone, "You have chosen unwisely!" The floor would shake, and your PC would glow white hot while your hard disk melted into a pool of molten silicon. Just kidding . . . sometimes the floor doesn&qt;&qt;t shake, but powering off a running Linux system without using the shutdown command will most certainly cause Bad Things to happen to your hard disk. So if you really want to exit Linux, be sure that you&qt;&qt;re logged in as the root user and enter the command
shutdown -h now
You&qt;&qt;ll see some messages indicating that various subsystems are being shut down, and then the computer will be reset. When you see a message indicating that shutdown is complete, it&qt;&qt;s safe to turn off your PC.
Tip: Pressing ctrl-alt-delete will also safely shut down your Red Hat Linux system. Just remember to power off as soon as you see your PC&qt;&qt;s normal bootup screen. Note that some other Linux distributions will do a hard reset (which may cause filesystem damage) instead of gracefully shutting down, so don&qt;&qt;t use ctrl-alt-delete on non-Red Hat systems unless you know it&qt;&qt;s safe.