Shutdown of the computer

Close all your programs saving the data as desired. From your GUI main menu (e.g., "K"), select "Logout". Then, from the logon screen, select: "System"-"Shutdown".

Alternatively, from a text terminal, press <Ctrl><Alt><Del> (the "three-finger salute", you press the three keys simultaneously), wait for the shutdown process to complete, and turn off your machine only after it starts rebooting again. If you are in X-windows, first switch to a text terminal by pressing <Ctr><Alt><F1> (three keys simultaneously).

Never turn off your machine without the proper shutdown or else you may have disk error messages next time you boot. (Typically, the errors resulting from improper shutdown will be repaired automatically during the next boot, but occasionally more serious problem may result, and then you may need to repair the files manually or re-install!)

If you prefer your computer to go to a halt after you press <Ctrl><Alt><Del> (instead of the default reboot), you can set this up by editing the file /etc/inittab. This file specifies something like this:

# Trap CTRL-ALT-DELETE

ca::ctrlaltdel:/sbin/shutdown -t3 -r now

As root, replace the option "-r" to "-h" so that the same fragment reads:

# Trap CTRL-ALT-DELETE

ca::ctrlaltdel:/sbin/shutdown -t3 -h now

The line starting with "#" is just a comment (it is for humans, it does not have any effect on the computer). The option "-t3" tells the shutdown command to wait 3 seconds before it starts killing processes. The options "-r" and "-h" stand for "reboot" and "halt" respectively, so they perform a shutdown to reboot or a shutdown to a system halt.

Root can also use the shutdown command directly. This command can be used for either local or remote shutdown of your computer, but is used mostly for remote shutdown when the local keyboard is not available so you cannot use <Ctrl><Alt><Del>. It can also be very useful if a program hangs so that the keyboard is no longer functional. For example:

telnet name_of_machine_with_no_operable_keyboard

[login as a user]

su

[give password]

Now either execute ps axu |more, find the process id of the offending command in the ps output and do

kill pid_of_offending_process

or reboot your machine with:

/sbin/shutdown -rn now

This command will shutdown really fast, bypassing standard (longer) shutdown procedure--useful when the system becomes really buggy (the option -n will make "shutdown" kill all the processes before rebooting).

Please note that for security reasons, you cannot login to a remote machine as root (e.g., over the telnet). You have to login as a user and then execute su and give a password to become a super user (root).

The shutdown command may also be used to execute a shutdown later. E.g. (as root):

/sbin/shutdown -r 23:59

will reboot the system 1 minute before midnight. I could also use:

/sbin/shutdown -r +1

to shutdown 1 minute from now. I can cancel a scheduled shutdown with:

/sbin/shutdown -c

If the shutdown command is too long for you, you may want to try these two commands, which do exactly what their names suggest (as root):

reboot

halt

A fancy way to shut down your computer is to switch your system to the runlevel 0 (for halt) or runlevel 6 (for reboot). Try it using (as root):

init 0

The meaning of the different runlevels is explained in the file /etc/inittab and here (FAQ.htm#GUI_login)