From mboxrd@z Thu Jan  1 00:00:00 1970
Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43)
	id 1FZEUL-00039r-EA
	for qemu-devel@nongnu.org; Thu, 27 Apr 2006 17:57:29 -0400
Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43)
	id 1FZEUK-00039f-39
	for qemu-devel@nongnu.org; Thu, 27 Apr 2006 17:57:28 -0400
Received: from [199.232.76.173] (helo=monty-python.gnu.org)
	by lists.gnu.org with esmtp (Exim 4.43) id 1FZEUJ-00039c-VY
	for qemu-devel@nongnu.org; Thu, 27 Apr 2006 17:57:28 -0400
Received: from [81.29.64.88] (helo=mail.shareable.org)
	by monty-python.gnu.org with esmtps
	(TLS-1.0:DHE_RSA_AES_256_CBC_SHA:32) (Exim 4.52) id 1FZEXJ-0001Lj-HN
	for qemu-devel@nongnu.org; Thu, 27 Apr 2006 18:00:33 -0400
Received: from mail.shareable.org (localhost [127.0.0.1])
	by mail.shareable.org (8.12.8/8.12.8) with ESMTP id k3RLvN5h022569
	for <qemu-devel@nongnu.org>; Thu, 27 Apr 2006 22:57:23 +0100
Received: (from jamie@localhost)
	by mail.shareable.org (8.12.8/8.12.8/Submit) id k3RLvNbi022567
	for qemu-devel@nongnu.org; Thu, 27 Apr 2006 22:57:23 +0100
Date: Thu, 27 Apr 2006 22:57:22 +0100
From: Jamie Lokier <jamie@shareable.org>
Subject: Re: [Qemu-devel] patch: configure: nonstandard use of `expr'
Message-ID: <20060427215722.GA21384@mail.shareable.org>
References: <20060427190105.GA15518@saturn.kn-bremen.de>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20060427190105.GA15518@saturn.kn-bremen.de>
Reply-To: qemu-devel@nongnu.org
List-Id: qemu-devel.nongnu.org
List-Unsubscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>
List-Archive: <http://lists.gnu.org/pipermail/qemu-devel>
List-Post: <mailto:qemu-devel@nongnu.org>
List-Help: <mailto:qemu-devel-request@nongnu.org?subject=help>
List-Subscribe: <http://lists.nongnu.org/mailman/listinfo/qemu-devel>,
	<mailto:qemu-devel-request@nongnu.org?subject=subscribe>
To: qemu-devel@nongnu.org

Juergen Lock wrote:
> At least FreeBSD's expr(1) doesnt understand the syntax now used in
> configure:
> 
> Index: qemu/configure
> @@ -157,7 +157,7 @@
>  fi
>  
>  for opt do
> -  optarg=`expr "$opt" : '[^=]*=\(.*\)'`
> +  optarg=`echo "$opt" |sed 's/^[^=]*=//'`
>    case "$opt" in
>    --help|-h) show_help=yes
>    ;;

The GNU Autoconf manual, and its code, recommends something like this
(note the "x" prefix):

  optarg=`expr "x$opt" : 'x[^=]*=\(.*\)'`

Your echo version suffers from non-portable results when opt matches "-n*",
"-e*", "-E*", or something with a backslash in.

-- Jamie