Date: Fri, 12 Nov 2010 10:05:37 +0100 (CET) From: Wojciech Puchar <wojtek@tensor.gdynia.pl> To: Matthias Apitz <guru@unixarea.de> Cc: freebsd-questions@freebsd.org Subject: Re: how to overwrite the content of a file Message-ID: <alpine.BSF.2.00.1011121005070.85478@tensor.gdynia.pl> In-Reply-To: <20101111200252.GA1350@tiny.Sisis.de> References: <20101111200252.GA1350@tiny.Sisis.de>
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dd if=/dev/zero of=file seek=x count=y bs=z conv=notrunc will overwrite y blocks of z size beginning from block x On Thu, 11 Nov 2010, Matthias Apitz wrote: > > Hello, > > What is the best method to overwrite the blocks of a given file with > bytes of 0x00, i.e. not to O_TRUNC away the blocks to the freelist of the > file system, but overwrite the old blocks? > > I've checked > > $ dd if=/dev/zero of=file count=4 > > but dd(1) opens the file with O_RDWR|O_CREAT|O_TRUNC which for sure will > give away the old blocks and adquire new blocks. Any idea? > > The background of the question is that I want to make sure, that certain > content is not placed into a dump of the file system before give away > the output of the dump(8). > > Thanks > > matthias > -- > Matthias Apitz > t +49-89-61308 351 - f +49-89-61308 399 - m +49-170-4527211 > e <guru@unixarea.de> - w http://www.unixarea.de/ > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org" > >
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