[Dev-luatex] Looking at a PDF/DVI while it is being produced

[David Kastrup]

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