Path: csiph.com!optima2.xanadu-bbs.net!xanadu-bbs.net!news.glorb.com!usenet.stanford.edu!not-for-mail
From: Stephane Chazelas <stephane.chazelas@gmail.com>
Newsgroups: gnu.bash.bug
Subject: Re: SIGINT handling
Date: Mon, 21 Sep 2015 22:24:03 +0100
Lines: 43
Approved: bug-bash@gnu.org
Message-ID: <mailman.1561.1442870652.19560.bug-bash@gnu.org>
References: <20150918151439.GA16455@chaz.gmail.com> <20150919203628.GA27872@chaz.gmail.com> <20150921094807.GA6229@chaz.gmail.com> <56005BC4.1070906@case.edu>
NNTP-Posting-Host: lists.gnu.org
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Cc: bug-bash <bug-bash@gnu.org>, Jilles Tjoelker <jilles@stack.nl>
To: Chet Ramey <chet.ramey@case.edu>
Envelope-to: bug-bash@gnu.org
Content-Disposition: inline
In-Reply-To: <56005BC4.1070906@case.edu>
User-Agent: Mutt/1.5.21 (2010-09-15)
Precedence: list
Xref: csiph.com gnu.bash.bug:11530

2015-09-21 15:34:28 -0400, Chet Ramey:
> On 9/21/15 5:48 AM, Stephane Chazelas wrote:
> 
> > I'm not sure I prefer that WCE approach over WUE. Wouldn't it be
> > preferable that applications that intercept SIGINT/QUIT/TSTP for
> > anything other than clean-up before exit/suspend implement job
> > control themselves instead (like vi's :! should create a process
> > group and make that the foreground process group of the
> > terminal so pressing ^C in sh -c vi, :!sleep 10, only sends the
> > SIGINT to sleep)?
> 
> The classic example is emacs remapping the terminal intr key to ^G
> and using SIGINT as its internal abort-command signal.
[...]

AFAICT emacs starts a new process group (and makes it the
foreground process group).

UID        PID  PPID  PGID   SID  C STIME TTY          TIME CMD
chazelas 12232  5595 12232 12232  0 15:00 pts/13   00:00:00     /bin/zsh
chazelas 13609 12232 13609 12232  0 22:14 pts/13   00:00:00       sh -c emacs; echo test
chazelas 13610 13609 13610 12232  0 22:14 pts/13   00:00:00         emacs

>From strace:

13766 setpgid(0, 0)                     = 0
13766 ioctl(3, TIOCSPGRP, [13766])      = 0

If it didn't, we could not use it in scripts of shells that
don't do WCE *but also in non-shell scripts* (perl, python,
ruby...) or non-scripts.

A real-life problem though is things like:

sh -c 'vi; echo hi'

Where if you run :!sleep 10 and interrupt it with Ctrl-C, the
"echo hi" is not run in shells that don't do WCE (and non-shell
scripts and non-scripts that don't do it either).

-- 
Stephane