Hi, sometimes on a long run one would like to be able to take a look at the current state of a PDF being produced. I don't know whether there is something like a progressive PDF format: likely not. But if I could send a signal to my PDFTeX/LuaTeX process, and this would cause it (at least if it would not currently be in a \shipout) to flush the current buffers, create a copy of the current PDF/DVI file under a snapshot name, properly finish/close it (writing reference table/DVI trailers) and then resume regular work, this would be quite dandy. I often have the situation of starting a dead slow 1400 page compilation where I really need the full output, but can probably see after looking at a dozen pages whether or not the whole compilation will be rubbish, needs some minor change and restart. Being able to use a signal for "give me a viewable snapshot PDF/DVI for the current state of the document" would be rather invaluable. It would be conceivable to offer this as an option to the TeX interactive prompt, by typing
mysnap.pdf
Then one could just interrupt PDFTeX using ^C as usual, and type this command for getting a snapshot. -- David Kastrup, Kriemhildstr. 15, 44793 Bochum