From owner-freebsd-questions@freebsd.org  Mon Sep 28 12:10:56 2015
Return-Path: <owner-freebsd-questions@freebsd.org>
Delivered-To: freebsd-questions@mailman.ysv.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 by mailman.ysv.freebsd.org (Postfix) with ESMTP id A81C9A0B28A
 for <freebsd-questions@mailman.ysv.freebsd.org>;
 Mon, 28 Sep 2015 12:10:56 +0000 (UTC)
 (envelope-from nospam@mgedv.net)
Received: from mail.mgedv.net (mail.mgedv.net [83.64.34.254])
 by mx1.freebsd.org (Postfix) with ESMTP id 67AE81AED
 for <freebsd-questions@freebsd.org>; Mon, 28 Sep 2015 12:10:55 +0000 (UTC)
 (envelope-from nospam@mgedv.net)
Received: from my.loop (client.my.loop [255.255.255.255])
From: "no@spam@mgEDV.net" <nospam@mgedv.net>
To: <freebsd-questions@freebsd.org>
Subject: 10.2-RELEASE/amd64: grep regex syntax vs. grep-bug
Date: Mon, 28 Sep 2015 13:37:35 +0200
Message-ID: <00e801d0f9e2$125ec430$371c4c90$@mgedv.net>
MIME-Version: 1.0
X-Mailer: Microsoft Outlook 14.0
Thread-Index: AdD54LgS+P+ZaDglRtqWs3EfyB5y0g==
Content-Language: de-at
Content-Type: text/plain;
	charset="us-ascii"
Content-Transfer-Encoding: 7bit
X-Content-Filtered-By: Mailman/MimeDel 2.1.20
X-BeenThere: freebsd-questions@freebsd.org
X-Mailman-Version: 2.1.20
Precedence: list
List-Id: User questions <freebsd-questions.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/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: <https://lists.freebsd.org/mailman/listinfo/freebsd-questions>, 
 <mailto:freebsd-questions-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 28 Sep 2015 12:10:56 -0000

hi folks,
the goal: grep, that a variable contains a number and JUST digits.
# setup sample variable - we're on /bin/sh @ 10.2-RELEASE/amd64.
x=""
# od output the content of the variable to ensure content
echo "$x" | od -ctdC
0000000   \n
           10
0000001
# now try /usr/bin/grep'pin (C locale) that it contains...
# ^          at BOL...
# [0-9]   require a digit
# *          ... and digits following
# $          ...until we reach EOL
# ... but...:
echo "$x" | grep -c '^[0-9]*$'
1             <== WHY?
it works if i remove the *, but this would only work for 1digit nrs.
is this a grep bug or my false understanding of how '*' works?