From owner-freebsd-questions@FreeBSD.ORG  Thu Oct 28 17:42:16 2010
Return-Path: <owner-freebsd-questions@FreeBSD.ORG>
Delivered-To: freebsd-questions@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 7217B106566C
	for <freebsd-questions@freebsd.org>;
	Thu, 28 Oct 2010 17:42:16 +0000 (UTC)
	(envelope-from freebsd@edvax.de)
Received: from mx02.qsc.de (mx02.qsc.de [213.148.130.14])
	by mx1.freebsd.org (Postfix) with ESMTP id 2E8AB8FC0A
	for <freebsd-questions@freebsd.org>;
	Thu, 28 Oct 2010 17:42:15 +0000 (UTC)
Received: from r55.edvax.de (port-92-195-16-227.dynamic.qsc.de [92.195.16.227])
	by mx02.qsc.de (Postfix) with ESMTP id 25189296B8;
	Thu, 28 Oct 2010 19:42:14 +0200 (CEST)
Received: from r55.edvax.de (localhost [127.0.0.1])
	by r55.edvax.de (8.14.2/8.14.2) with SMTP id o9SHexnA001881;
	Thu, 28 Oct 2010 19:40:59 +0200 (CEST)
	(envelope-from freebsd@edvax.de)
Date: Thu, 28 Oct 2010 19:40:59 +0200
From: Polytropon <freebsd@edvax.de>
To: FreeBSD Questions <freebsd-questions@freebsd.org>
Message-Id: <20101028194059.c9c643e3.freebsd@edvax.de>
In-Reply-To: <20101028192826.d3211524.freebsd@edvax.de>
References: <20101027212841.GA67716@guilt.hydra>
	<20101028151148.GB73337@libertas.local.camdensoftware.com>
	<20101028160110.GA71713@guilt.hydra>
	<20101028161712.GC73337@libertas.local.camdensoftware.com>
	<20101028192826.d3211524.freebsd@edvax.de>
Organization: EDVAX
X-Mailer: Sylpheed 2.4.7 (GTK+ 2.12.1; i386-portbld-freebsd7.0)
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: Chip Camden <sterling@camdensoftware.com>
Subject: Re: [OT] writing filters in sh
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
Reply-To: Polytropon <freebsd@edvax.de>
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-questions>
List-Post: <mailto:freebsd-questions@freebsd.org>
List-Help: <mailto:freebsd-questions-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
	<mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 28 Oct 2010 17:42:16 -0000

On Thu, 28 Oct 2010 19:28:26 +0200, Polytropon <freebsd@edvax.de> wrote:
> On Thu, 28 Oct 2010 09:17:12 -0700, Chip Camden <sterling@camdensoftware.com> wrote:
> > Perhaps someone with more sh fu can transform the
> > 'if' paragraph into a one-liner at least.  When I tried to do so, I got an
> > unexpected ; error.
> 
> Not tested, but this should do the trick:
> 
> 	#!/bin/sh
> 	if [ $# -ge 1 ] && ( exec cat $@ | $0; exit )
> 	while read data; do echo $data; done

Attention - does NOT work! Maybe my sh fu is just shhh foo. :-)

 	#!/bin/sh
 	[ $# -ge 1 ] && ( exec cat $@ | $0; exit )
 	while read data; do echo $data; done

THIS is better. You can see that "if" has been removed, leaving
a call to the program "test" (/bin/test is /bin/[), as long as
sh does not use a built-in test or [ mechanism. The "if" is not
neccessary here, as the if-then-fi construct is implicated by
the use of &&.

Tested. Works.




-- 
Polytropon
Magdeburg, Germany
Happy FreeBSD user since 4.0
Andra moi ennepe, Mousa, ...