On 23 Jan 2003, Sam Steingold wrote:
control-alt-backspace (C-M-BS) is an important key combination in Emacs,
usually bound to backwards-kill-sexp.
in XFree86-4.2.99.3 (as comes with Red Hat beta phoebe),
it is not available to Emacs, see bug
<https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=81947>
usually, C-M-BS kills the X server, so you need to enable the
DontZap option in /etc/X11/XF86Config.
xev(1) reports C-M-BS as
KeyPress event, serial 25, synthetic NO, window 0x2c00001,
root 0x3f, subw 0x0, time 65848720, (154,149), root:(162,184),
state 0x0, keycode 37 (keysym 0xffe3, Control_L), same_screen YES,
XLookupString gives 0 bytes: ""
KeyPress event, serial 25, synthetic NO, window 0x2c00001,
root 0x3f, subw 0x0, time 65848733, (154,149), root:(162,184),
state 0x4, keycode 64 (keysym 0xffe9, Alt_L), same_screen YES,
XLookupString gives 0 bytes: ""
KeyRelease event, serial 25, synthetic NO, window 0x2c00001,
root 0x3f, subw 0x0, time 65849308, (154,149), root:(162,184),
state 0xc, keycode 22 (keysym 0xfed5, Terminate_Server), same_screen YES,
XLookupString gives 0 bytes: ""
some files in /etc/X11/xkb/symbols/ mention "Terminate_Server".
fortunately, a simple
$ xmodmap -e 'keycode 22 = BackSpace'
fixes the problem, but this is an extremely inconvenient default.
This is not an XFree86 bug. Ctl-Alt-BackSpace has killed the server as
far back as I can remember. Certainly before 2.0, and likely before
emacs.
Fix emacs.
