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MathGroup Archive 1998

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Re: Re: Corrupted NB

  • To: mathgroup at smc.vnet.net
  • Subject: [mg14508] Re: [mg14419] Re: Corrupted NB
  • From: gwinn at ma.ultranet.com (Joe Gwinn)
  • Date: Thu, 29 Oct 1998 04:33:09 -0500
  • Sender: owner-wri-mathgroup at wolfram.com

I have been bitten by this too.

There is a simple way Wolfram could at least make Mathematica aware that
a prefs file had become corrupted -- put a simple checksum on it.

By the way, there is a simple trick I sometimes use oon apps that eat
their prefs file -- manually make a backup copy, and/or manually
write-lock the prefs file, so the app cannot write to its own prefs
file.  Most apps will tolerate this, although I haven't tried it with
Mathematica.

Joe



At 1:39 AM 98/10/23, Garrett Tim Sos wrote:
>Maybe this idea should also apply to the preferences files
>that still (version 3.0.1.1x) become corrupted (on the
>Mac, atleast) so often that I no longer try to change from the
>factory default preferences.
>
>I logged a call to WRI on a different issue and asked about
>the preferences file corruption problem and got the answer that
>it was "the computer's fault" implying that they did not
>feel it needed to be fixed.
>
>Maybe he was just having a bad day but sometimes it is hard
>to like WRI.  I have been using Mathemetica since
>Version 1.1.  It is a wonderfully complex creation but
>3.0's habit of destroying user INPUT (preferances, notebooks
>and strange corruption of cells) is dreadful.
>
>Tim
>
>
>Joe Gwinn wrote:
>>
>> I have also had this problem, but I have never succeeded in fixing a
>> damaged notebook.  The problem has always happened when Mathematica
>> crashed while saving the notebook  Now I periodically make a no-output
>> backup copy called "<whatever>.nb short" so I don't lose everything
>> when Mathematica crashes.
>>
>> This kind of destroy-file-on-save behaviour was very common in early
>> (mainframe and mini) computer software, and subsequently in early PC
>> and Mac software, but is now mostly a thing of the bad old days.  The
>> standard solution is to do file saves in such a way that there is never
>> a window of vulnerability, where a computer crash (for whatever reason)
>> could leave one with only a corrupted file.
>>
>> The method?  Simple.  One 1970s variant:  Open a temporary file and
>> write the new version of the document into it.  If successful, rename
>> the old file with a temporary name, and then rename the just-written
>> temporary file (containing the new document) to be the updated file.
>> Delete the old file with the temporary name.  No matter when the crash,
>> there is at least one good file surviving, perhaps with a temporary
>> name.  Temporary files are not deleted on a crash, so this can work.
>>
>> This does require that one have scratch disk space sufficient to carry
>> an extra copy of the file, but this is generally true, especially in
>> this day of multi-gigabyte disks.  More to the point, this method was
>> used even when disks were tiny, so one can conclude that users would
>> rather have bulletproof file saves than the extra disk space.
>>
>> Joe Gwinn
>>
>> In article <70dd69$234 at smc.vnet.net>, "Kevin J. McCann"
>> <kevinmccann at Home.com> wrote:
>>
>> > I have a NB which when I try to run it tells me that there was a syntax
>> > error.  The popup goes on to say that I can open it as a text file,
>> > etc.  Is there a way to recover from this.  The problem appears to have
>> > been generated when Mathematica crashed.
>> >
>> > Kevin



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