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David K. Watson - dvipng problem

David K. Watson - dvipng problem

by Arnold Pizer -
Number of replies: 0
inactiveTopicdvipng problem topic started 9/18/2005; 5:46:36 PM
last post 9/18/2005; 6:55:46 PM
userDavid K. Watson - dvipng problem  blueArrow
9/18/2005; 5:46:36 PM (reads: 367, responses: 2)
Our students have suddenly started getting the message

cd /local/webwork2/tmp/ImageGenerator.f7Y6WudJ && /usr/bin/dvipng -bgtransparent -D120 -q -depth equation > dvipng.out 2> dvipng.err returned non-zero status 34304: Inappropriate ioctl for device at /local/pg/lib/WeBWorK/PG/ImageGenerator.pm line 361.

This is happening for a large fraction of problems, but not for all of them. To make sure this is really the case, I made up a completely new problem set and viewed the problems, and I still saw the behavior that some equations would display and others would not. It is the same dvipng status 34304 error every time an error occurs. I checked to see if the image files are being created despite the error messages, and they aren't.

A possible trigger for this behavior is that I restarted Webwork last night, and I also ran dvipng without any input to see which version we are using (it is version 1.0 ). I do not see why either of these should have this effect, though.

I have tried everything I can think of to troubleshoot this error and am coming up blank. Any help would be appreciated.

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userDavide P. Cervone - Re: dvipng problem  blueArrow
9/18/2005; 6:08:02 PM (reads: 444, responses: 0)
Has something changed with /local/webwork2/tmp recently? The error message is a file system error that seems to be complaining about the tmp directory where the images will be created. Do you see ImageGenerator.f7Y6WudJ in that directory? Can you create such a directory by hand?

The reason that some images are showing up is probably because they are already in the equation cache, so didn't need to be created. Only new equations will fail.

You might try setting 

   $WeBWorK::PG::ImageGenerator::PreserveTempFiles = 1;
in /local/webwork2/lib/WeBWorK/Constant.pm so that the temporary files and directories aren't removed, and then look in the webwork2/tmp/ImageGenerator.XXXXXX directory to see if there is anything telling in there. If the .tex or .dvi file is there, you could try running dvipng by hand to see if there are any useful messages.

Davide

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userDavid K. Watson - Re: dvipng problem  blueArrow
9/18/2005; 6:55:46 PM (reads: 434, responses: 0)
Never mind, all is fine now.

It turns out that someone (not me!) was looking around at dvipng files and inadvertently made a change in one of them. I had suspected that something like this might have happened but was not looking for a changed file in the right place. We will all try to be more careful with our file-browsing in the future.

I am glad that I apparently have the right instincts. I had checked nearly all of your suggestions.

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