Do not just turn off the computer! You risk losing valuable data!
If you are the only user of your computer, you might want to turn the computer
off when you're done with it.
To avoid possibly weakening some hardware components, only turn off the computer
when you're done for the day. Power up and power down are the two greatest contributors
to wear and tear on computer components. Turning the computer on and off once
a day is probably the best compromise between your electric bill and your computer's
It's a bad thing to just press the power switch when you're done using the computer.
It is also bad to reboot the machine (with the Reset button) without first taking
proper precautions. The Linux kernel, in order to improve performance, has a
disk cache. This means it temporarily stores information meant for
permanent storage in RAM. Because memory is thousands of times faster than a
disk, this makes many file operations move more quickly. Periodically, the information
Linux has in memory is actually written to the disk. This is called syncing.
In order to turn off or reboot the computer safely, you'll have to tell the
computer to clear everything out of memory and put it in permanent storage.
To reboot, just type reboot or press Ctrl-Alt-Del (that's
Ctrl, Alt, and Delete).
To shut down, you'll have to log in as root. As root, just type the
command shutdown -h now. The sytem will go through the entire shutdown
procedure, including the sync command, which clears the disk cache
as described above. When you see System halted, it's safe to turn off
the computer. If you have Advanced Power Management (APM) support in your kernel
and BIOS, the computer might shut itself off and save you the trouble. APM is
common in laptops and is also found in certain desktop mainboards.