question about cleaning free space.

[der153]

So I was cleaning out my computer as I was selling it and I then ran ccleaner on it. I was using the drive wiper to clean up free space. I ran the option to clean free space with 3 passes

The scan's progress went up to 80% and I was running short on time and had to give my computer away.

My question is that if the scan only went up to 80% does that mean the free space wasn't cleaned fully or had the free space been ran through at least once already since I was doing 3 passes.

How does it work? does an advanced overwrite go through the system deleting all the free space until about 33% then do another pass in this sequence or does it run through each file 3 times then goes onto the next?

Basically, I just want to know if my system's free space had been cleared and passed through at least once like a simple overwrite (one pass).

[Augeas]

I don't think that any of us knows. I imagine that the first task is to allocate enough files to fill free space, before running the multiple passes, in which case you already have one overwrite (the file allocation) should the file allocation be completed. But that's only my imagination.

[Nergal]

From my understanding of how this process works, @Augeas is correct and summed it up perfectly.

 

[mta]

if you had to stop the wipe free space before completion, would there now be no space left as that zzzzzz? thing file it creates will still be there?

or does it get automatically removed at next reboot - I can't remember.