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I don't remember why they did this, but at one point X.org decided that disabling CtrlAltBackspace to kill it was a good idea. I know there's a way to re-enable it but I don't remember how. Can someone refresh my memory?

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5 Answers 5

up vote 18 down vote accepted

Modify /etc/X11/xorg.conf with the following. (note: it is ok if this is all you have in your xorg.conf as xorg will still auto-detect the rest (note: that is if auto-detect works for you without it))

Section "ServerFlags"
    Option "DontZap" "false"

Section "InputClass"
    Identifier      "Keyboard Defaults"
    MatchIsKeyboard "yes"
    Option          "XkbOptions" "terminate:ctrl_alt_bksp"
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They seriously disabled this by default? No wonder it hasn't been working! –  gabe. Aug 13 '10 at 18:47
yes and it happened like 5 years ago. –  xenoterracide Aug 13 '10 at 18:54
When you don't have to zap your xwindows very often, sometimes its easy to miss a change that happened 5 years ago... –  Bryan Rehbein Aug 16 '10 at 20:08
@Redbeard eh... xorg (and drivers) and kwin have been doing enough screwing around that I occasionally have to do it, and half the time I find out it's been disabled and I haven't re-enabled since my last reinstall. –  xenoterracide Aug 17 '10 at 18:30
In some distributions (e.g. recent Fedoras) these kinds of additional settings should probably be placed in /etc/X11/xorg.conf.d as a conf file, e.g. 10-enable-ctrl-alt-backspace. –  Tommi Kyntola Jan 7 '14 at 12:43

you can try following ( I have tried it on my Ubuntu) :

Add the following lines to your xorg.conf file, making sure that when you paste it, it is NOT using smart quotes.

sudo gksudo gedit /etc/X11/xorg.conf

Section "ServerFlags"
Option "DontZap" "false"

you can also try dontzap tool

sudo apt-get install dontzap

Open Terminal and type to enable

sudo dontzap --enable

for disable

sudo dontzap --disable

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I really wish they had never turned this off by default. oh, and apt-get doesn't work on my system ;) apparently we haven't packaged dontzap either. oh well. –  xenoterracide Aug 12 '10 at 7:20
did you try first solution ? –  Hemant Aug 12 '10 at 7:28
setxkbmap -option terminate:ctrl_alt_bksp by itself that didn't work :( apparently you need to do this too. –  xenoterracide Aug 12 '10 at 7:29
@Hermant of course but it seems to be only 1/2 of it. I actually have it working now... there's a way to configure the xsetkbd option in xorg.conf. like so Section "InputClass" Identifier "Keyboard Defaults" MatchIsKeyboard "yes" Option "XkbOptions" "terminate:ctrl_alt_bksp" EndSection there are several other places it could be done too. –  xenoterracide Aug 12 '10 at 9:55
It will be gr8 if you can put your solution as Answer. So that others facing same issue can get help :-). –  Hemant Aug 12 '10 at 10:06

http://who-t.blogspot.com/2009/04/zapping-server.html explains the change and how to change it back.

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The DontZap feature is no longer working for me on Fedora 16 and Ubuntu 11.10 (most recent releases as of November 2011), so I found an alternative.

According to the X11R7.5 release notes, it appears that this functionality has been migrated to a XKB configuration option, therefore DontZap no longer works. I can't tell if this is a detail of the Xorg implementation in Fedora and Ubuntu, or if this affects other distros as well.

From http://www.x.org/archive/X11R7.5/doc/RELNOTES.txt

Terminate Server keystroke

The Xorg server has previously allowed users to exit the server by pressing the keys Control + Alt + Backspace. While this function is still enabled by default in this release, the keymap data usually used with Xorg, from the xkeyboard-config project, has been modified to not map that sequence by default, in order to reduce the chance that inexperienced users will accidentally destroy their work.

Users who wish to have this functionality available by default may enable it via the XKB configuration option “terminate:ctrl_alt_bksp”. For instance, the setxkbmap command can be used to enable this by running:

       setxkbmap -option "terminate:ctrl_alt_bksp"                       

Many desktop environments include XKB configuration options in their preferences to enable this as well.

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my answer still works as of 7.6 –  xenoterracide Nov 22 '11 at 7:01

In current Ubuntu releases, at least since 14.10, the keyboard-configuration package has an option to re-enable Zap:

$ sudo dpkg-reconfigure keyboard-configuration
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