From owner-freebsd-questions@FreeBSD.ORG Wed Nov 17 19:55:23 2010 Return-Path: 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 8FE90106566B for ; Wed, 17 Nov 2010 19:55:23 +0000 (UTC) (envelope-from dan@dan.emsphone.com) Received: from email2.allantgroup.com (email2.emsphone.com [199.67.51.116]) by mx1.freebsd.org (Postfix) with ESMTP id 55A058FC12 for ; Wed, 17 Nov 2010 19:55:23 +0000 (UTC) Received: from dan.emsphone.com (dan.emsphone.com [199.67.51.101]) by email2.allantgroup.com (8.14.4/8.14.4) with ESMTP id oAHJtME6069439 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 17 Nov 2010 13:55:22 -0600 (CST) (envelope-from dan@dan.emsphone.com) Received: from dan.emsphone.com (smmsp@localhost [127.0.0.1]) by dan.emsphone.com (8.14.4/8.14.4) with ESMTP id oAHJtLUH031172 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Wed, 17 Nov 2010 13:55:22 -0600 (CST) (envelope-from dan@dan.emsphone.com) Received: (from dan@localhost) by dan.emsphone.com (8.14.4/8.14.4/Submit) id oAHJtLgr031171; Wed, 17 Nov 2010 13:55:21 -0600 (CST) (envelope-from dan) Date: Wed, 17 Nov 2010 13:55:21 -0600 From: Dan Nelson To: Alexander Best Message-ID: <20101117195521.GF57869@dan.emsphone.com> References: <20101117155006.GA88394@freebsd.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101117155006.GA88394@freebsd.org> X-OS: FreeBSD 8.1-STABLE User-Agent: Mutt/1.5.21 (2010-09-15) X-Virus-Scanned: clamav-milter 0.96.4 at email2.allantgroup.com X-Virus-Status: Clean X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.6 (email2.allantgroup.com [199.67.51.78]); Wed, 17 Nov 2010 13:55:22 -0600 (CST) X-Scanned-By: MIMEDefang 2.68 on 199.67.51.78 Cc: freebsd-questions@freebsd.org Subject: Re: a question regarding proper printf(3) formating and alignment X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 17 Nov 2010 19:55:23 -0000 In the last episode (Nov 17), Alexander Best said: > hi there, > > i've looked at a lot of utilities in the bsd src tree and most of them > seem to be doing something like this: > > Device 1M-blocks Used Avail Capacity > /dev/label/swapfs 10239 0 10239 0% > /dev/label/swap 8191 0 8191 0% > Total 18431 0 18431 0% > > as you can see the header simply gets written with a number of tabs in > between the keywords, but then the actual output aligns differently. > > i'd like to learn of ways formatting the header so that it aligns > properly, whether the device name is 10 chars long or 1000. is there an > example for this somewhere in the src tree? /bin/ls does this for the user, group, and size columns. Note that this only works if you batch up your output (or take two passes over your input data). I seem to remember /usr/bin/find doing this dynamically by expanding columns as it saw values that were larger than the previous max, but apparently not (I just tested it). -- Dan Nelson dnelson@allantgroup.com