# Redefine \pdfouput=1 to be ignored

How I can redefine the command `\pdfoutput=1` to be ignored?

I need to compile a file with `lualatex` (see https://tex.stackexchange.com/a/586129/33634) but it contains the command `\pdfoutput=1`. I cannot make changes to the file so I thought I can redefine it at some point. Maybe with `\AtBeginDocument` or with `etoolbox`'s `\AtEndPreamble` passing it to the engine.

How can I achieve it?

• \newcount\pdfoutput somewhere before the command should work. – Ulrike Fischer Mar 6 at 22:12

It is a counter variable (primitive, but still), so

``````\newcount\pdfoutput
``````

should do. That's not a great idea though, because some code may use that to check if pdfTeX is being used and the test will give a false positive.

• tests relying on it are bound to break anyway, e.g. if luatex85 is loaded, so imho one doesn't need to worry about it. – Ulrike Fischer Mar 6 at 22:14
• @UlrikeFischer Curiously there are lots of `\ifx\pdfoutput\@undefined` and such in my installation (surely, most are likely fine, but there are a few that can be problematic). Probably the value of `\pdfoutput` (in an engine that doesn't have it) is more important than it existing or not... Anyway, just rambling :) – Phelype Oleinik Mar 6 at 22:20
• It works. Thanks. Works also with `\pdfminorversion`. – Gabriele Nicolardi Mar 6 at 22:25
• @GabrieleNicolardi Yes, all are count registers (you can do `\<register>=<number>`) so will work in the same way. If you have some dimension register, for example `\pdfpagewidth`, you can use `\newdimen` instead – Phelype Oleinik Mar 6 at 22:30

If you compile from the command line,

``````lualatex "\let\pdfoutput\outputmode\input filename"
``````

will do.