From owner-freebsd-questions@FreeBSD.ORG Sat Dec 19 20:43:07 2009 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 2C11810656C1 for ; Sat, 19 Dec 2009 20:43:07 +0000 (UTC) (envelope-from mexas@bristol.ac.uk) Received: from dirg.bris.ac.uk (dirg.bris.ac.uk [137.222.10.102]) by mx1.freebsd.org (Postfix) with ESMTP id DD9DC8FC0C for ; Sat, 19 Dec 2009 20:43:06 +0000 (UTC) Received: from seis.bris.ac.uk ([137.222.10.93]) by dirg.bris.ac.uk with esmtp (Exim 4.69) (envelope-from ) id 1NM68k-0002BM-So; Sat, 19 Dec 2009 20:43:06 +0000 Received: from mech-cluster241.men.bris.ac.uk ([137.222.187.241]) by seis.bris.ac.uk with esmtp (Exim 4.67) (envelope-from ) id 1NM68k-0004FB-10; Sat, 19 Dec 2009 20:43:02 +0000 Received: from mech-cluster241.men.bris.ac.uk (localhost [127.0.0.1]) by mech-cluster241.men.bris.ac.uk (8.14.3/8.14.3) with ESMTP id nBJKh1SK009995; Sat, 19 Dec 2009 20:43:01 GMT (envelope-from mexas@bristol.ac.uk) Received: (from mexas@localhost) by mech-cluster241.men.bris.ac.uk (8.14.3/8.14.3/Submit) id nBJKh1AR009994; Sat, 19 Dec 2009 20:43:01 GMT (envelope-from mexas@bristol.ac.uk) X-Authentication-Warning: mech-cluster241.men.bris.ac.uk: mexas set sender to mexas@bristol.ac.uk using -f Date: Sat, 19 Dec 2009 20:43:01 +0000 From: Anton Shterenlikht To: Warren Block Message-ID: <20091219204301.GA9957@mech-cluster241.men.bris.ac.uk> References: <20091218005102.GA51064@mech-cluster241.men.bris.ac.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-Spam-Score: -1.5 X-Spam-Level: - Cc: Anton Shterenlikht , freebsd-questions@freebsd.org Subject: Re: editing a binary file 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: Sat, 19 Dec 2009 20:43:07 -0000 On Thu, Dec 17, 2009 at 06:38:04PM -0700, Warren Block wrote: > On Fri, 18 Dec 2009, Anton Shterenlikht wrote: > > > I'm creating binary files in fortran. > > Fortran adds 4 byte record delimiters at the beginning > > and the end of each record, which, in the case of a binary > > file, is just at the beginning and at the end of the file. > > I need to delete these record delimiters, because the > > software I use to visualise the binary files interprets > > them as data. But I don't know how. I've looked at > > hexdump and od, but those are only dumping (I think) > > file contents, and I cannot see how to edit a file with them. > > truncate -4 myfile should get rid of the last four bytes. Maybe there's > a similar efficient way to truncate the start of a file. thank you, that works fine: > hexdump -C fort.10 00000000 01 00 00 00 01 01 00 00 00 |.........| 00000009 > truncate -s -4 fort.10 > hexdump -C fort.10 00000000 01 00 00 00 01 |.....| 00000005 > -- Anton Shterenlikht Room 2.6, Queen's Building Mech Eng Dept Bristol University University Walk, Bristol BS8 1TR, UK Tel: +44 (0)117 331 5944 Fax: +44 (0)117 929 4423