I am using the common PDF command line program, pdftk.exe, to generated custom-made PDFs with variable data. In time, there is a need to delete some of these, for which I am using the PHP unlink() function.
Every once in a while, one rogue PDF that has been generated from pdftk.exe (called from the same PHP program) coughs up some permissions issues, keeping it from being deleted. I am perplexed because it is only this one rogue one once in a while, and all the others delete just fine. I also don't think it is an issue with the specific BASE pdf used to generate the one with variable data, because I know I have successfully deleted some generated from that same base PDF.
Can you clue me in? What could be causing this just once in a while? There are very few clues, and like I said the base PDF doesn't appear to be a key to the cause.