msm <msm@domain.invalid> wrote:
> To kick in a suggestion, DBAN (Darik's Boot And Nuke - googleable) can be
> slow, but claims to be effective against most reasonable attempts to
> recover data.

I've heard that recommended before.

> Note that erasing a disk pretty much mandates not running an OS off it at
> the same time....

Why? This is UNIX; it will run just fine [1] if the machine it is on
suddenly goes diskless. Just compile yourself a program that writes
random data into whatever file is named on the command line, repeats
this a couple of times, and then zeroes the drive for good measure, and
run it.

Of course, you'll want to shut down by turning off the computer.

Joachim

[1] As long as you don't access the disk, do not need swap, etc, at
least. But that's not too difficult to arrange on a quiet system.