Scrub free disk blocks

[JD]

  On 08/27/2010 09:25 PM, JD wrote:
>  Is there a Linux util to scrub free disk blocks and keep everything 
> else intact ??
>
Someone (not on this list) described a simple way to do this.
Scrubbing files to be deleted is easy enough - there are utils for it 
already.
But scrubbing existing free space is slower and requires patience.

cd to the root of the partition.
sudo dd if=/dev/zero of=ZERO bs=20M

When the dd program fails to write any further, you
have grabbed and zeroed all available free disk blocks
in the partition.

Now all you do is use the command scrub to scrub the file ZERO
and when done  the file is deleted.