Any better ways to ensure that deleted files are non recoverable?

[derekmcwilliams]

Hello guys,

I'm preparing to sell my 17" G4 Powerbook to a friend but Im not going to reinstall the OS - theres some software on there that Ive bought off the internet but since lost the installer / serials etc.

Id like to ensure that all the files that I have deleted, some deleted not using the 'secure trash' method are non-recoverable - and I dont know of the best way to do so...

So... I did the following: while true; do cat sometextfilewithrandomtextin >>/testfile done ... and just waited for my disk to fill up and then rm'd the file... it's VERY crude but also quick.

For all of those that really know the guts of Mac FS (HFS is it?), should this be sufficient?

Thanks in advance...

 

[wordmunger]

It sounds like that would work, but if you really want to be sure, I'd get something like drive genius, which can check your drive for file fragments and securely delete them. I guess it's a question of whether you trust your friend, or whether it's worth $99 to be sure.

 

[Mitthrawnuruodo]

Why not use Disk Utility's built-in Erase Free Space...?

 

[derekmcwilliams]

Yep, its just like me to overlook the things right under my nose..

..theres my feet.

Thanks!

 

[janey]

try cat /dev/random next time haha.

Or, the better way, remove the drive altogether and replace it with a new one (if that's an option).

Odds are though, your friend won't care enough/doesn't know enough to get the data back even after just a cursory erase.

 

[iHotu]

.

 

[ChrisA]

So... I did the following: while true; do cat sometextfilewithrandomtextin >>/testfile done ... and just waited for my disk to fill up and then rm'd the file... it's VERY crude but also quick.
.

That would likey easae it but there is stil a chance of some data recovry. For example the swap space would not be erased and there might be some data that was held in RAM once still in not yet overwritten swap.
There are caches and temp files that you may not have found and deleted. You can't know if you got them all

Around here when a disk once held clasified data theyhave a way of deleting it -- they disasseble the drive, remove the platters then physically destroy them. Nothing short of this can have 100% provable certainty.

 

[mmcxiiad]

zeroing the data out when you format makes the restoration of data more difficult. imagine data recovery like layers. the more times you write over that part of the drive the harder it is to restore it. this can also be done in disk utility.... but fyi - the process isn't quick.