Date: Thu, 17 Dec 2009 20:45:02 -0500 From: Greg Larkin <glarkin@FreeBSD.org> To: Warren Block <wblock@wonkity.com> Cc: Anton Shterenlikht <mexas@bristol.ac.uk>, freebsd-questions@freebsd.org Subject: Re: editing a binary file Message-ID: <4B2ADE9E.6080707@FreeBSD.org> In-Reply-To: <alpine.BSF.2.00.0912171820130.53881@wonkity.com> References: <20091218005102.GA51064@mech-cluster241.men.bris.ac.uk> <alpine.BSF.2.00.0912171820130.53881@wonkity.com>
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-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 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. > > -Warren Block * Rapid City, South Dakota USA This should do it: dd if=oldfile of=newfile bs=1 skip=4 Hope that helps, Greg - -- Greg Larkin http://www.FreeBSD.org/ - The Power To Serve http://www.sourcehosting.net/ - Ready. Set. Code. http://twitter.com/sourcehosting/ - Follow me, follow you -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.7 (MingW32) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iD8DBQFLKt6e0sRouByUApARAt0uAJ9CfG3DmsUbrUMg7hX2dIT+FOZ1sACfQtaD b7z5vvm/+vohelNIch1/ME8= =Zp5i -----END PGP SIGNATURE-----
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