This is a frequently asked question on linux lists. It usually generates quite a bit of debate because the military doesn't usually tell people what they can do so you can only speculate on what it would take to destroy the data so that even the military can't recover it. Certainly, if you destroy the platter physically by doing something like hitting it with a hammer, that should do it.
But most people believe that just wiping the disk a dozen or so times will do it. You can do that with the dd command lie this:
Dd if=/dev/random of=/dev/sda
ThatÂ’s if your disk is a sata drive. For IDE drives, the command would be:
Dd if=/dev/random of=/dev/had
Those commands write random digits over the entire drive, wiping out the boot sector, partition table, and all data. You would have to do that several times because the read/write heads might not line up exactly right to destroy every single bit if you do it just once.
-----Original Message-----
.From: "Ibraam Wahib"