27 May
1999
27 May
'99
3:56 p.m.
a PC. Another
technique I have used when I didn't have immediate access
to a wiping program (and *think* it is okay although not as good as
doing a wipedisk) is to overwrite the offending file with another
larger one, i.e. "copy [bigfile.ext] [offending file.ext]" and of
course, then deleting the
This may not work. On RT11 (I think) it certainly won't work. What some OS's do is create the new file in a
suitable (contiguous) free
area on the disk and then mark the existing file as unused space. RT11
does this because all files have to be contiguous on that OS.
Good explanation...
Of course then the original (deleted) data is still on
the disk.
Yep...
Deleting files and then compressing an RT11 disk should
be OK unless the
files are at the end of the disk. Compressing and then creating a large
file (large enough to overwrite the rest of the disk) should be safe.
Unfortunately not... the only way to guarantee it is if there are LOTS
of files on the disk, and the file deleted existed at a point in the
directory less than the total size of all the following files. Too much
to have to check before you are sure it is gone...
Teh creation of the large file simple creates a directory entry... the
actual disk surface defined by the new entry is not touched, so the
data could still be there, hidden inside the larger file. Now if you
did something to that file to overwrite it's contents, then it would
be gone.
It's been a while since I had to do this, and I had a program to do it
for me anyway... but on a stock RT-11, you might be able to mount the
file as a logical device, then FORMAT or INIT it, or do a COPY/DEV
to it...
Megan Gentry
Former RT-11 Developer
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| Megan Gentry, EMT/B, PP-ASEL | Internet (work): gentry!zk3.dec.com |
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