Just as Linux has a fairly involved startup process [LINK] it needs to go through several steps before you turn off the power to your computer. During these shutdown steps Linux stops programs and saves data. For this reason, you should never power down your computer directly (for example, while logged into the IceWM desktop). Instead, you should let Linux go through its shutdown sequence before turning off power to your computer.
Linux is a fairly robust operating system. It can usually withstand sudden losses of power -- the next time you boot up your computer, Linux will notice that it has been shut down unexepectedly and try to recover its data. However, it is possible that you could lose data or corrupt files, and in the worst case your computer might refuse to boot again without human intervention. [REF TO TROUBLESHOOTING]
The first step in shutting down your computer is to save your work and close the applications you have open. Don't count on your application programs to save your data automatically for you; some applications will, and others will not.
After saving your work press ctrl-alt-delete . That is, press the ctrl key, then while holding that key down press alt, then while holding those two keys down press delete. Pressing this sequence should bring up the following IceWM menu: [SCREENSHOT][REF TO "How to use this manual"?]
To shut down your machine, click on Shutdown. The following (not very helpful) dialog box appears: [SCREENSHOT]
Although the dialog box talks about "Logout" and not "Shutdown", your computer will start the shutdown process if you click. Not surprisingly, clicking will cancel the process.
After clicking, the computer may beep. Then you will leave the graphical desktop and go back into text-only mode. Messages will scroll by on the screen for a while. Eventually you will see the words "Power Down" at the bottom of your screen. [SCREENSHOTS] When you see this message it is safe to turn off your computer.
Under normal circumstances, the easiest way to shutdown your computer is from the IceWM desktop. However, you might click the wrong buttons or hit the wrong keystrokes and find yourself in some other environment. For example, if you accidentally click the <mi>Logout</mi> entry in the program menu, you will find yourself on a screen that looks like this: [SCREENSHOT]
If you find yourself on this screen and you want to turn off your computer, press ctrl-alt-delete . Linux will go through the shutdown process, and then reboot your computer. When your computer starts rebooting (during the memory test, the POST screen, or the GRUB menu) you may safely power off your computer. [REF TO BOOTUP CHAPTER].
Another way to shutdown your machine is to use the command line. To do this, open an X-Terminal-Emulator or Xterm window. At this window, type
/sbin/shutdown -h now
The computer will print the following message:
The system is going down for system halt NOW!
and then run through the shutdown process. Again, you should wait until you see the Power Down message before turning off your computer.