Spelunking the places where files are not

[emanuel stiebler]

On 2021-03-05 09:41, John Foust via cctalk wrote:
> 
> This situation makes me hesitant to release disk images from the past.
> It's one thing to do it with disks that were mine and to take responsibility
> for my risk; it's another to release disks once owned and used by others.
> Do the unused sectors contain their love letters from 1983?  
> 
> Or if I want to release disk images that contain known personal files,
> how will I image, then remove specific files, then zero unused blocks
> if I don't want to alter the original media?

I started to do something in this direction, using a lot of virtual
machines ...

Before I make backups, I write a file with zero content, until it fills
up the filesystems (something like dd if=/dev/zero of=/ttt.tmp ; rm ttt.tmp)

Two benefits:
a.) there shouldn't be any hidden stuff anymore
b.) the file containers can be zipped nicely, as all unused stuff is zero

Hope it helps ...