From owner-freebsd-hackers@FreeBSD.ORG Thu Jun 25 12:15:52 2009 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 37A4A106564A for ; Thu, 25 Jun 2009 12:15:52 +0000 (UTC) (envelope-from a_best01@uni-muenster.de) Received: from zivm-out2.uni-muenster.de (ZIVM-OUT2.UNI-MUENSTER.DE [128.176.192.9]) by mx1.freebsd.org (Postfix) with ESMTP id BD5D68FC0A for ; Thu, 25 Jun 2009 12:15:50 +0000 (UTC) (envelope-from a_best01@uni-muenster.de) X-IronPort-AV: E=Sophos;i="4.42,290,1243807200"; d="scan'208";a="217027501" Received: from zivmaildisp2.uni-muenster.de (HELO ZIVMAILUSER03.UNI-MUENSTER.DE) ([128.176.188.143]) by zivm-relay2.uni-muenster.de with ESMTP; 25 Jun 2009 14:15:49 +0200 Received: by ZIVMAILUSER03.UNI-MUENSTER.DE (Postfix, from userid 149459) id 8B5BF1B075E; Thu, 25 Jun 2009 14:15:49 +0200 (CEST) Date: Thu, 25 Jun 2009 14:15:49 +0200 (CEST) From: Alexander Best Sender: Organization: Westfaelische Wilhelms-Universitaet Muenster To: Matthew Seaman Message-ID: In-Reply-To: <4A420073.6060405@infracaninophile.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: Wojciech Puchar , Julian Elischer , freebsd-hackers@freebsd.org Subject: Re: small usr.bin/find patch X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 25 Jun 2009 12:15:52 -0000 wow. thanks a bunch for all the great info. Matthew Seaman schrieb am 2009-06-24: > Alexander Best wrote: > > hmmm...but dd e.g. uses lowercase instead of upercase letters to > > indicate > > kilobyte, megabyte and so on. isn't there some unix/posix/whatever > > standard > > telling app developers what to use? > Sure. The standard for scale-prefixes is defined by the Systeme > Internationale as part of the definition of SI units: > http://www.npl.co.uk/reference/measurement-units/si-prefixes/ > Note that these are strictly powers-of-10^3 multipliers, and > explicitly > not the computing style powers-of-2^10 commonly used for file sizes > or > hard drive capacities, which should instead use the somewhat clunky > Ki, > Mi, Gi etc. forms: > http://physics.nist.gov/cuu/Units/binary.html > These binary prefixes are mandated by the IEC and approved by the > IEEE > amongst others. > Not that many people use the binary prefixes appropriately, relying > on > context to disambiguate 1 MB = 1024 KB = 1,048,576 Bytes etc. Except > that (confusingly) as a measure of network bandwidth 10 Mb/s always > was > 10,000,000 b/s and never 10,485,760 b/s; a fact that has caught me > out > more than a few times. > Making find(1) / dd(1) / etc. operate pedantically correctly with > these > scale-factor symbols would cause a certain degree of pain for little > practical gain. Unless there was a broad consensus amongst all > Unixoid > OS providers, I can't see that change ever happening. > Cheers, > Matthew