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Old 06-02-2009
jake24 jake24 is offline
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Join Date: May 2009
Posts: 7
Unhappy Erasing hard disk contents using dd or dcfldd

Hi,

I am writing a script to wipe my hard disk, in a relatively secure manner by over-writing the disk with 3 patterns. So, I run the dd/dcfldd command 3 times with a sync call in between each command call in the script.

Code:
#!/bin/sh
dcfldd pattern=99 conv=notrunc of=/dev/sda
sync
dcfldd pattern=jj conv=notrunc of=/dev/sda
sync
dcfldd pattern=hell conv=notrunc of=/dev/sda
sync
I want to know if the above code would in fact,result in my hard disk being over-written with the given patterns in that order? Since I have introduced a sync in between each command call, any remaining buffers to be written onto the disk would have been physically written before the next pattern is being copied to the disk by dcfldd.

Please help me. I really want to understand the impact.