Xorg Server 1.6.x and Ctrl-Alt-Backspace
This question seems to pop up everywhere now that a lot of linux distributions are incorporating xorg-server 1.6.x. Ctrl-Alt-Backspace used to restart your X server in previous versions and as a result it would log out the active user leaving him at the login manager if he uses any or leaving him at the command line if he doesn”t. It sort of became cultural linux heritage. Even the novice linux user somehow knew this trick.
The xorg devs have decided to disable this functionality as of 1.6.0. I tried investigating why they disabled it, but at some point I just gave up. I’ve read a lot of speculations by users on this topic but no official developer giving an explanation. Some claim it’s because of frequently closing the X server by accidently pressing this key combination, others just say it’s more secure to disable the key combination.
Personally, I don’t find any of the two valid reasons. I don’t really see how you can accidently press Ctrl-Alt-Backspace. There is no key combination that vaguely comes anywhere near this one. Maybe Ctrl-Alt-Del comes close but that isn’t really a combination that is tied to a consistent action. Then there’s this so called security risk. As if being able to log out some user is a security risk. The security risk is physical access, not being able to log someone out.
Then again, you can enable it back again by editing the /etc/X11/xorg.conf file. Adding:
Section "ServerFlags" Option "DontZap" "false" EndSection
will make Ctrl-Alt-Backspace work again. If you’re using xorg server 1.6.1 or later, you’ll have to do some additional stuff. Either add
<merge key="input.xkb.options" type="string">terminate:ctrl_alt_bksp</merge>
to your /etc/hal/fdi/policy/10-keymap.fdi file or run
setxkbmap -option terminate:ctrl_alt_bkspeverytime after you started X.
So does this all matter? Maybe it does. Not every user has sufficient privileges to edit this file. So if you’re not the user at the workstation, you’re not supposed to log of (our so called security risk) his or her session. Powering off the pc willin the end have the same effect, which makes disabling ctrl-alt-backspace obsolete. I guess it will only bother people.