Re: how to overwrite the content of a file
El día Thursday, November 11, 2010 a las 02:16:33PM -0600, Adam Vande More escribió: 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? ... Well there is rm -P although I'm not sure that accomplished exactly what you are looking for. Yes, thanks. This is exactly what I need. matthias -- Adam Vande More -- Matthias Apitz t +49-89-61308 351 - f +49-89-61308 399 - m +49-170-4527211 e g...@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-unsubscr...@freebsd.org
Re: how to overwrite the content of a file
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 g...@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-unsubscr...@freebsd.org ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
how to overwrite the content of a file
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 g...@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-unsubscr...@freebsd.org
Re: how to overwrite the content of a file
In the last episode (Nov 11), Matthias Apitz said: 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? conv=notrunc (note that this will only help with ufs; zfs is always copy-on-write, so newly-written data never overwrites the old blocks) -- Dan Nelson dnel...@allantgroup.com ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
Re: how to overwrite the content of a file
On Thu, Nov 11, 2010 at 2:02 PM, Matthias Apitz g...@unixarea.de wrote: 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? Well there is rm -P although I'm not sure that accomplished exactly what you are looking for. -- Adam Vande More ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to freebsd-questions-unsubscr...@freebsd.org
