X-Recipient: archive-cygwin AT delorie DOT com
X-SWARE-Spam-Status: No, hits=-1.7 required=5.0	tests=AWL,BAYES_00,KHOP_RCVD_UNTRUST,RCVD_IN_HOSTKARMA_W,RCVD_IN_HOSTKARMA_WL,RP_MATCHES_RCVD,SPF_HELO_PASS
X-Spam-Check-By: sourceware.org
Message-ID: <5059AFD1.9050501@ptc.com>
Date: Wed, 19 Sep 2012 13:43:13 +0200
From: Roeder Roland <rroeder AT ptc DOT com>
User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:15.0) Gecko/20120907 Thunderbird/15.0.1
MIME-Version: 1.0
To: <cygwin AT cygwin DOT com>
Subject: Re: tcsh hang while executing scripts which use pipes with backticks
Content-Type: text/plain; charset="ISO-8859-1"; format=flowed
Content-Transfer-Encoding: 7bit
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
List-Id: <cygwin.cygwin.com>
List-Subscribe: <mailto:cygwin-subscribe AT cygwin DOT com>
List-Archive: <http://sourceware.org/ml/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-help AT cygwin DOT com>, <http://sourceware.org/ml/#faqs>
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Delivered-To: mailing list cygwin AT cygwin DOT com

After various different attempts to nail down this issue I have some hope
now that I have found a fix for it. I analyzed the changes of last to
current version of tcsh and found one that is related to context of the
problem and somewhat suspicious as well. The change I did then was the 
following:

$ diff -uN sh.glob.c.orig sh.glob.c
--- sh.glob.c.orig      2012-09-17 13:20:26.212401000 +0200
+++ sh.glob.c   2012-09-17 13:20:23.916171400 +0200
@@ -787,7 +787,7 @@
             /* The F_BACKQ flag must set so the job output is correct if
              * printexitvalue is set.  If it's not set, the job output
              * will have "Exit N" appended where N is the exit status. */
-           t->t_dflg = F_BACKQ|F_NOFORK;
+           t->t_dflg |= (F_BACKQ); /*|F_NOFORK);*/
             if (seterr)
                 stderror(ERR_OLD);
  #ifdef SIGTSTP

The comment along with the change of t_dflg was added in latest tcsh 
release.

Main change from me was to not set F_NOFORK. That fixed my test case. 
Whether
or not it is ok to overwrite t_dflg or simply add the bit I can't say. I 
tried both.
It made no difference for my test case.

I know that this is probably not the right forum to post this, since the 
issues seems
to be in tcsh but not in cygwin. However, I thought I post it here for 
the other
folks suffering from this problem as well. Maybe they want to try the 
fix as well.

regards

--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple