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

David Kastrup dak at gnu.org
Sat Mar 8 14:20:40 CET 2008

Taco Hoekwater <taco at elvenkind.com> writes:

> David Kastrup wrote:
>
>> 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.
>
> The idea is interesting, but I have absolutely no time to implement
> it.  I fear that getting the details right may take quite some time
> (forking is easy, the tricky bit is duplicating the open files and
> file handles).

Most of the file handles would likely be best served by just closing
them (in order not to mess up the output of the continuing process).

>> 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.
>
> Can't you just interrupt tex always and at the error prompt "I\end" ?
> If the PDF turns out to be OK after all, you will have to generate
> 1414 or so pages, a 10% overhead, not that bad compared to generating
> 2800.

Well, actually the workflow is to trigger a snapshot, peruse it to its
end, trigger another snapshot, and so on.  The first runs will probably
be bad on the first dozen pages, but later runs might get increasingly
further before a problem requiring a fix and rerun crops up.

--
David Kastrup, Kriemhildstr. 15, 44793 Bochum