I often get asked the best way to securely erase a disk or what to use to ensure that a disk has been sanitised to DoD 5220-22-M. A reasonable way to achieve this would be: dd if=/dev/urandom of=/dev/rdsk/c#t#d#s2 bs=10k or dd if=/dev/arandom of=/dev/r#d#c bs=10k This will ensure that random (not completely random, but good enough) …