On  8 May 98 at 10:30, Len Warner wrote:

> ***B. a security issue
>
> If it's for confidentiality (you want to be sure the deleted files
> cannot be recovered) you should use a security delete utility ON
> THE ORIGINAL FILES that overwrites the physical storage space before
> releasing it back to DOS. Just to be sure, you should fill all
> space on the affected drive with dummy data. (And if you use Win95,
> you did empty the Recycle Bin first, didn't you?) A friend of mine
> has a batch command that copies the contents of the MS-DOS
> directory repeatedly to fill the disk.

  Note that in an era of DriveSpace and other compression
technologies, a "security delete utility" is very hard to get right;
there's no guarantee that the data written back "over" the file
contents will be the same *size*, or stored in the same physical disk
sectors.
  Sooner or later, the OS is going to try to re-use the disk space of
deleted files, and your friend's approach forces that to happen
within a few minutes.  That and a defrag should eliminate all trace
of the original file data, although its directory entry (minus the
first letter) may persist a bit longer.

David G