Shutting down a Debian system

From NewbieDOC

Chris Lale
chrislale AT users DOT berlios DOT de

Go to NewbieDOC index

Revision History


Version 1.0 10th February 2007 Revised by Chris Lale
Initial release

Version 1.1 26th November 2007 Revised by Chris Lale
Reformatted for newbiedoc package; added Abstract and Licence appendix.


Image:Newbiedoc-32.png Stable document
You can comment on this document by clicking on the discussion tab.

You can edit the live version of this document: Shutting down a Debian system


Abstract

Newbies often tend to press the RESET button to stop/restart a Debian system. This is the equivalent of pulling the plug - you are risking file corruption. Here is some help about how to shut down your Debian system safely.

Contents


1 Introduction

Pressing the RESET button is the equivalent of pulling the plug - you are risking file corruption. Here are some safer ways to shut down your system. Adapted from posts in a thread on the Debian-user list (http://lists.debian.org/debian-user/2007/02/msg01393.html). As with so much in GNU/Linux, there is more than one solution.


2 Shutting down from a console screen

You can use these methods even without being logged in.

2.1 Shutting down a local machine

If you are used to another operating system, you may know about the Ctrl-Alt-Del key combination. You must first switch to a virtual console (text only screen) before you can use this method for shutting down Debian.

Switch to one of the six virtual consoles (Ctrl-Alt-F1, Ctrl-Alt-F2, ..., Ctrl-Alt-F6) by holding down the Ctrl and Alt keys and tapping one of the function keys "F1" - "F6". At the console screen, issue the reboot key combination Ctrl-Alt-Del (ie hold down the "Ctrl" and "Alt" keys, and tap the "Del" or "Delete" key).

Ctrl-Alt-F1
Ctrl-Alt-Del 

Wait until the system shuts down and the restart begins,then power down the system. You can power down safely anytime before Grub begins to boot the system.

 
Tip
Tip: 
One of your first post-install tasks in Debian might be to comment out the "timeout 5" line in "\boot\grub\menu.lst". This will make sure that Grub does not boot until after you press the "Enter" key.

Alternatively, if you wish Grub to boot automatically but wish to be able to prevent the system from booting, change the delay from 5 seconds (which is much too

short) to 10 or 15 seconds.
 

2.2 Shutting down an unresponsive local machine

If a machine is really not responsive (which happens once in a while) you can try these three key combinations in sequence : Alt+SysRq+S, Alt+SysRq+U and Alt+SysRq+O. They synchronise the discs ("S"), unmount the discs ("U") and turn the system off ("O"). It is important that you issue all three commands in the correct order so that you avoid data corruption.

Alt+SysRq+S
SysRq: Emergency Sync
Emergency Sync complete

Alt+SysRq+U
SysRq: Emergency Remount R/O
Emergency Remount R/O complete

Alt+SysRq+O 
SysRq: Power off
Shutdown

This will minimize the chance of data loss but isn't a long term solution.

If you wish to reboot the system rather than shutting down, use Alt+SysRq+B instead of Alt+SysRq+O.

Alt+SysRq+B
Resetting

You can find out more about key combinations at http://linux.about.com/od/linux101/l/blnewbie5_1.htm .

3 Shutting down from a shell prompt

If you are logged in to a console you can shut the system down from the shell prompt. You can also use this method from a desktop environment by first obtaining a shell prompt by running a "Terminal" application.

3.1 Shutting down a local machine

At the prompt, switch user ("su") to user root (see also the talk/discussion page).

$ su
(enter root's password)
#

The standard way to shut down is to enter

# shutdown -h now

An alternative is to enter

# halt
The System is going down for halt now!

If you include the "-p" switch, the system will also poweroff.

# halt -p

If you wish to reboot rather than shutting down, use the "-r" switch instead.

# shutdown -r now

An alternative is to enter

# reboot

3.2 Shutting down a remote machine

If your machine is in a network and Debian has booted, you can access the machine by SSH from another machine in the network. Log in as user root via SSH, and shut it down using one of the "shutdown" commands (see .html#Shutting down from a shell prompt). This works even if the remote keyboard or screen have locked up.


4 Shutting down from a GUI environment

4.1 Shutting down from the login screen

After X starts, but before you have logged in, you should be presented with a graphical login screen. This is provided by the display manager. The default display manager is the Gnome Display Manager ("gdm"). There is an "Actions" menu with a "Shut down the computer" item. You can use this without logging in and without needing a password.

4.2 Shutting down from the Gnome desktop

Once logged into Gnome, you should find "Shut Down" in the "Desktop" menu in the top panel.

 
Note
Note: 
You can add a "shutdown" button to the panel by right-clicking on the panel.
 

4.3 Shutting down from the KDE desktop

Once logged into KDE, you can right click with the mouse pointer over the "desktop" (background), which produces a menu with a number of options, the one you want being "Log out user" (where user is replaced by your login name). This will bring up another window with four selections. "End Current Session" just logs you out, the next two will power down or reboot.


5 Modify the action of the POWER button

Provided your machine is ACPI compliant, install the package "acpid". It contains a script /etc/acpi/powerbtn.sh and a symbolic link to that (/etc/acpi/events/powerbutton). With that you can just hit the power button of your machine and your system will gracefully do a shutdown to halt and then power off.


6 Appendix A: Licence

Copyright (c) 2007 Chris Lale. chrislale AT users DOT berlios DOT de

GNU FDL Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.2 or any later version published by the Free Software Foundation with no Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the license is included in the section entitled "GNU Free Documentation License."

Go to NewbieDOC index

Content is available under GNU Free Documentation License 1.2, unless otherwise stated.