From owner-freebsd-bugs@FreeBSD.ORG  Fri Apr  3 19:40:05 2009
Return-Path: <owner-freebsd-bugs@FreeBSD.ORG>
Delivered-To: freebsd-bugs@hub.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id A38FC1065676
	for <freebsd-bugs@hub.freebsd.org>;
	Fri,  3 Apr 2009 19:40:05 +0000 (UTC)
	(envelope-from gnats@FreeBSD.org)
Received: from freefall.freebsd.org (freefall.freebsd.org
	[IPv6:2001:4f8:fff6::28])
	by mx1.freebsd.org (Postfix) with ESMTP id 3BC468FC21
	for <freebsd-bugs@hub.freebsd.org>;
	Fri,  3 Apr 2009 19:40:05 +0000 (UTC)
	(envelope-from gnats@FreeBSD.org)
Received: from freefall.freebsd.org (gnats@localhost [127.0.0.1])
	by freefall.freebsd.org (8.14.3/8.14.3) with ESMTP id n33Je4Y2098758
	for <freebsd-bugs@freefall.freebsd.org>; Fri, 3 Apr 2009 19:40:04 GMT
	(envelope-from gnats@freefall.freebsd.org)
Received: (from gnats@localhost)
	by freefall.freebsd.org (8.14.3/8.14.3/Submit) id n33Je4Gx098757;
	Fri, 3 Apr 2009 19:40:04 GMT (envelope-from gnats)
Date: Fri, 3 Apr 2009 19:40:04 GMT
Message-Id: <200904031940.n33Je4Gx098757@freefall.freebsd.org>
To: freebsd-bugs@FreeBSD.org
From: Jilles Tjoelker <jilles@stack.nl>
Cc: 
Subject: Re: bin/34811: sh(1) "jobs" is not pipeable
X-BeenThere: freebsd-bugs@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: Jilles Tjoelker <jilles@stack.nl>
List-Id: Bug reports <freebsd-bugs.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-bugs>,
	<mailto:freebsd-bugs-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-bugs>
List-Post: <mailto:freebsd-bugs@freebsd.org>
List-Help: <mailto:freebsd-bugs-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-bugs>,
	<mailto:freebsd-bugs-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 03 Apr 2009 19:40:06 -0000

The following reply was made to PR bin/34811; it has been noted by GNATS.

From: Jilles Tjoelker <jilles@stack.nl>
To: bug-followup@FreeBSD.org, slaven.rezic@berlin.de,
	Martin.Kaeske@stud.tu-ilmenau.de, kerochan2@gmail.com
Cc:  
Subject: Re: bin/34811: sh(1) "jobs" is not pipeable
Date: Fri, 3 Apr 2009 21:34:18 +0200

 The way I read POSIX, I think this does not have to work. Commands in a
 pipeline with two or more commands may or may not be executed in a
 subshell (this 'or' applies to each of the commands individually), and a
 subshell has its own list of unwaited jobs.
 
 Accordingly,  (jobs)  gives empty output (in /bin/sh as well as bash4).
 bash4 seems to do special trickery with the jobs command in pipelines
 (as permitted): even in commands like  jobs >`tty` | jobs  both give
 proper output. This, however, breaks down if you make it more
 complicated such as by replacing  jobs  with  { jobs; }.
 
 On the other hand, $(jobs) works in both /bin/sh and bash4, although
 POSIX says that command substitution happens in a subshell. However,
 POSIX also mentions $(jobs -p) in an informative section, and it seems
 useful.
 
 If you want to add this feature, evalpipe() in eval.c would probably be
 the place. It would be quite specific to very few builtin commands which
 tend not to be used much in scripts. (Note that slow operations in the
 main shell process cannot be ^Z'ed, and that builtin commands may be
 overridden with functions.)
 
 -- 
 Jilles Tjoelker