Clearing the unallocated disk space

[Fred Smith]

On Sun, Nov 16, 2014 at 12:04:31PM -0700, jd1008 wrote:
> Before sending the drive for warranty service, what is the best way to
> clean the unallocated blocks?
> 
> The rest of the files on disk are OK - standard installation, ... etc.
> All home dirs are deleted, tmp dirs, logs ....etc all deleted.
> If you can think of other things to delete, pls let the world know.

if you're sending it in for warranty service/replacement, why would
you not want to just wipe the whole drive? 

easy is dd if=/dev/zero of=/dev/sdX (where sdX is whatever location
in /dev attaches to your drive). possibly more than once.

there's also a utility that is designed to securely wipe the drive.
ufortunately I'm having a senior moment and can't think of its name.

or as someone else suggested, use /dev/zero to write one huge file 
that fills all the blank space, then delete it (or not, as you see
fit.)

you could /dev/random or /dev/urandom instead of /dev/zero, but they
tend to be pretty slow.

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