does zsh ignore the QUIT signal?

does zsh ignore the QUIT signal?

[Vincent Lefevre]

When I type "while true; do true; done" from an interactive zsh shell,
I can't interrupt it with SIGQUIT (either with Ctrl-\ or with the
"kill -QUIT <pid>" command): sending this signal has no effect. Is
this normal?

Searching for QUIT in the zsh man page, I just get:

SIGNALS
  The INT and QUIT signals for an invoked command are ignored if the com-
  mand  is  followed by `&' and the MONITOR option is not active.  Other-
  wise, signals have the values inherited by the shell  from  its  parent
  (but see the TRAPNAL special functions in the section `Functions').

whereas in the bash man page, this behavior is documented:

SIGNALS
  When bash is interactive, in the  absence  of  any  traps,  it  ignores
  SIGTERM (so that kill 0 does not kill an interactive shell), and SIGINT
  is caught and handled (so that the wait builtin is interruptible).   In
  all  cases,  bash  ignores  SIGQUIT.  If job control is in effect, bash
  ignores SIGTTIN, SIGTTOU, and SIGTSTP.

-- 
Vincent Lefèvre <vincent@vinc17.org> - Web: <http://www.vinc17.org/>
100% accessible validated (X)HTML - Blog: <http://www.vinc17.org/blog/>
Work: CR INRIA - computer arithmetic / SPACES project at LORIA

Re: does zsh ignore the QUIT signal?

[Peter Stephenson]

Vincent Lefevre wrote:
> When I type "while true; do true; done" from an interactive zsh shell,
> I can't interrupt it with SIGQUIT (either with Ctrl-\ or with the
> "kill -QUIT <pid>" command): sending this signal has no effect. Is
> this normal?

Yes, although I had to search the source code to find this out.  The
shell has ignored it at least as far back as the CVS archive goes (April
1999).

This should let you interrupt the shell with it:
  TRAPQUIT() { return $(( 128 + $1 )); }
It doesn't set the return status, unlike SIGINT, however (and because
it's handled there's no core dump).

This documents it.

Index: Doc/Zsh/jobs.yo
===================================================================
RCS file: /cvsroot/zsh/zsh/Doc/Zsh/jobs.yo,v
retrieving revision 1.4
diff -u -r1.4 jobs.yo
--- Doc/Zsh/jobs.yo	2 Jul 2004 14:59:14 -0000	1.4
+++ Doc/Zsh/jobs.yo	29 Mar 2006 19:04:07 -0000
@@ -95,6 +95,7 @@
 The tt(INT) and tt(QUIT) signals for an invoked
 command are ignored if the command is followed by
 `tt(&)' and the tt(MONITOR) option is not active.
+The shell itself always ignores the tt(QUIT) signal.
 Otherwise, signals have the values
 inherited by the shell from its parent
 (but see the tt(TRAP)var(NAL) special functions in noderef(Functions)).

-- 
Peter Stephenson <p.w.stephenson@ntlworld.com>
Web page still at http://www.pwstephenson.fsnet.co.uk/