Re: SBCL 2.3.11: Core dump after typing Control-4

On 2025-06-22 at 16:51:21 -0400,
[email protected] wrote:

>    I have not been able to find the following documented
> anywhere in the SBCL documentation (I have looked in the man
> page, the Info file included with SBCL version 2.3.11, and
> the latest manual at
> https://sbcl.sourceforge.io/manual/index.html) or from a
> search of the sbcl-help mailing list archives at 
> https://sourceforge.net/p/sbcl/mailman/sbcl-help/.
> 
> If I start SBCL from a shell prompt with:
> 
>   sbcl --no-user-init
> 
> and then type Ctrl-4 (Control key plus the digit 4) at the
> initial REPL prompt, then the characters ^\ appear and
> shortly after that, SBCL exits with the message:
> 
>    Quit (core dumped)
> 
> I have been able to reproduce this through numerous restarts
> of SBCL.
> 
> Is this expected behavior, and if so, is it a documented
> feature or is it undocumented?  My search of the SBCL
> documents only found Control-D and Control-C mentioned as
> documented key bindings.

I'm not an SBCL maintainer, but I'm old enough to know a keyboard
generated QUIT signal when I see one.  :-)

What happens when you run the following command from a shell prompt:

    stty -a

Somewhere in the middle of mine, I see quit = ^\, which means that
Control-\ (sometimes rendered as ^\) sends a QUIT signal to the process
on the termimal.  Quitting (and possibly dumping core) is the way that
SBCL responds to that signal.

A good start would be to identify your operating system and shell, but
changing that behavior is going to be very system- and login- specific.
A quick fix might be to run rlwrap or GNU Readline instead of just the
raw TTY driver.

HTH
Dan