From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <zsh-users-return-16353-mason-zsh=primenet.com.au@zsh.org>
Received: (qmail 3590 invoked by alias); 14 Sep 2011 19:37:11 -0000
Mailing-List: contact zsh-users-help@zsh.org; run by ezmlm
Precedence: bulk
X-No-Archive: yes
List-Id: Zsh Users List <zsh-users.zsh.org>
List-Post: <mailto:zsh-users@zsh.org>
List-Help: <mailto:zsh-users-help@zsh.org>
X-Seq: 16353
Received: (qmail 8613 invoked from network); 14 Sep 2011 19:37:09 -0000
X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on f.primenet.com.au
X-Spam-Level: 
X-Spam-Status: No, score=-2.0 required=5.0 tests=BAYES_00,DKIM_SIGNED,
	DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FROM,RCVD_IN_DNSWL_NONE,UNPARSEABLE_RELAY
	autolearn=ham version=3.3.1
Received-SPF: none (ns1.primenet.com.au: domain at yahoo.fr does not designate permitted sender hosts)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yahoo.fr; s=s1024; t=1316028703; bh=llP7Mhbn16RYKvyud4u4tw2ES7RT2wVAyCqKbZImfK4=; h=X-Yahoo-Newman-Id:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:Received:Date:From:To:Cc:Subject:Message-ID:Mail-Followup-To:References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To:User-Agent; b=hyLRdOBnk+5KOfpOIO255mclzgreOociNiCParI9KslJJ7XSUX1IBFUJNFK30thT7zZRre+N0enZbWD8a048Rw6TKIKxrwlcKrg/W8lrN2bq/JarFOGQS16wO44AGygsofzurydKIuxgVq5wPAvS5o44xGHGVwcD+9aIHH6/YnU=
X-Yahoo-Newman-Id: 844077.21738.bm@smtp138.mail.ukl.yahoo.com
X-Yahoo-Newman-Property: ymail-3
X-YMail-OSG: WEB4gAcVM1lqUqulfYj4QCggUuBvdSeY3YcSTmV_AAeXkrq
 Rl1PBjpqL
X-Yahoo-SMTP: V1UR0WuswBDVD1eFhM33188Ir8ciBckz4W8ZMsAh
Date: Wed, 14 Sep 2011 20:31:41 +0100
From: Stephane Chazelas <stephane_chazelas@yahoo.fr>
To: Peter Stephenson <p.w.stephenson@ntlworld.com>
Cc: zsh-users@zsh.org
Subject: Re: {fd}< and compound commands
Message-ID: <20110914193141.GB7325@yahoo.fr>
Mail-Followup-To: Peter Stephenson <p.w.stephenson@ntlworld.com>,
	zsh-users@zsh.org
References: <20110914172148.GA7325@yahoo.fr>
 <20110914200601.72c91f87@pws-pc.ntlworld.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20110914200601.72c91f87@pws-pc.ntlworld.com>
User-Agent: Mutt/1.5.21 (2010-09-15)

2011-09-14 20:06:01 +0100, Peter Stephenson:
[...]
> {
>   exec {fd}<file
> 
>   while read; do
>     ...
>   done <&$fd
> } always {
>   exec {fd}<&-
> }

Thanks Peter,

Why the "always" here?

> (although in this particular case there's nothing to stop you doing
> 
> while read var; do
>   ...
> done <file
> 
> but I presume you have something more complicated in mind.)
[...]

Well, using fd 0 here is dangerous as you never know if commands
in the loop will attempt to read from it (think of ssh without -n
for instance), or you may actually want them to read from (the
original) stdin.

-- 
Stephane