Shutdown for a single computer
The most common way of shutting down a single user Linux system is for you as root to issue the command:
shutdown -h now
You use this when you plan on shutting your computer off at that moment, as opposed to some later time.
You'll see a message like:
Linux is going for system halt NOW
It will start to shut off programs that you're computer is using and you'll see it all happening. That's because Linux is a transparent system. It lets you see everything it's doing. It won't give you a simple message telling you to wait and then another one telling you you can shut it off now. If something is causing a problem, it will tell you about it when it starts up and when it shuts down. That way, if you are having a problem, you may be able to track it down. If you don't know how to solve it, you can tell another person what you saw and he or she may be able to help you.
With the shutdown -h now command, you must wait until you see the message:
before you shut off the computer.