#HOW DELETED IS DELETED?
8 messages in this thread
I used the File Utility to delete a couple of drawing files. I now have
regrets — but UNERASE seems to be unable to find any remnants. Could it be
that ACAD 'wipes' deleted files in lieu of a simple DOS-style erase?
ps. I can reaquire the 340kB drawing from backups, and the other was just a
WBLOCK of a small part of the big drawing, so all I'm out is time…but was
just curious. If it turns out that ACAD does NOT 'wipe' deleted files, then
I need to either take a closer look at my system, or see the nice man in the
white coat.
Thanks….Dan
AutoCAD uses an awful lot of intermediate files, creating and deleting them
on the fly during the course of a session (as you'll discover if you reboot
rather than exiting AutoCAD — there will be temporary files sitting
around.) Thus, if you delete a file, then continue an AutoCAD session, it
is more than likely that the space freed up by the deleted file would be
used real quickly by an ACAD temporary file, thus zapping any hope for
unerase to work.
Thanks, Josh, for the reply on file deletions. I'm used to seeing at least
a fragment of a file when I try to Unerase…but I see what you're saying
about ACAD using so many temporary files, that the space could have been
taken up. I don't recall having gotten back into the graphics screen after
doing the deletions, though. And one of the files was 340 kB, so it would
have taken a lot of "filling up"!
Well…as The Whistler (or was it the Green Lantern…?)said, "Who knows what
evil lurks in the heart of a CPU." Or something like that…
Thanks….Dan
Dan:
FWIW, I think it was my old friend Lamont Cranston (a.k.a. The Shadow) who
said that. The response to the rhetorical was "The Shadow knows; ha ha ha
ha ha ha" (sinister laughter, for a while!).
—– Chuck
Dan – AutoCAD's FILES/Delete utility doesn't do any file scrubbing or
wiping; it simply issues the DOS function to delete a file. So perhaps the
space that had been used by those files was consumed by other files, or
even by the drawing file you were working on at the time (or the temporary
files used by AutoCAD).
Thanks, Duff — I'm not sure why the files that I deleted would disappear.
I don't believe that I returned to the drawing screen after deleting the
files in the Main Menu screen. Perhaps there is some file-saving activity
when you enter "0", to leave the Main Menu, but I would have thought that
the bridge from drawing screen to Main Menu would have ended any file saving
(or deleting of temp files, for that matter).
Anyhoo…just curious. For me, it's just as easy to do my housekeeping from
the DOS prompt, so I sould have no future reason for concern. At any rate,
I appreciate your comments!
See ya….Dan
Dan,
I'll send those nice men with the white coats over to see ya…<grin>
They'll even have a new jacket for ya to wear…but you might have some
diffuculty typing after putting it on.
ACAD itself doesn't do anything to deleted a file, the entries in the
standard ACAD.PGP file and the FILES utility menu all just do basic dos
DELETE oprtations – nothing more fancy than that. The reason that your files
may not have been UNERASEable is that ACAD will continue to open new
temporary files while you are continuing to wotk in the drawing editor. When
a new temo file (or even the new version of the curent file created by a
SAVE or END command) can simply grab the directory entry slot the USED to
have been the home of your deleted file's directory entry. As soon as DOS
deletes a file, the only thing it does is to mark the directory entry as
deleted. Any subsequent file creation calls (by ACAD or any other program,
for that matter) will look for the first, sequential, open directory slot
(including any deleted file slots) in the directory list. It will then use
this directory slot for itself, permanently erasing the deleted file's
directory entry. This is probably what happened to you.
Better luck next time!<grin>
Regards,
Mark Burns – [Network TM]
Thanks, Mark, for all your comments except the white coat one! You don't
have to be *quite* so cooperative!!
My mental disturbance (well…the AutoCAD one) arises from my recollection
that I did not re-enter the drawing editor after having deleted the files.
Of course, if the part about my going loony is applicable……
Thanks….Dan <finger on lips going blip-ip-ip-ip-ip-idib> Crimmins