[PLUG] Getting a root prompt upon booting

[Jeff Schwaber]

> > dd if=/dev/zero  of=/dev/hda  bs=512
> > 
> > Let that run till done..
> 
> The data on the drive is still very easily recoverable after that,
> however.  Shoot, you could probably do it from Windows.  :-)
> 
> I feel safe after dd'ing it with zero once, then with /dev/urandom
> twice.  The data on the drive is still recoverable at that point... but

Whoa, whoa, whoa...

seriously? How? dd in theory is supposed to write a zero to each bit of
the drive. That this leaves residual magnetic charge doesn't surprise
me, but enough that you can read it without breaking open the drive in a
sterile environment and putting its platters under some serious
inspection? And a couple /dev/urandom's does too?

Explain?

Jeff