# Why is aucTeX compiling my file like pdflatex “input” foo.tex rather than just pdflatex foo.tex?

When I compile a file using Emacs AucTeX with `C-c C-c` (which runs `TeX-command-master` which runs `TeX-run-TeX`) the top line of the log output looks like this:

``````Running `LaTeX' on `mwe' with ``pdflatex  -interaction=nonstopmode "\input" mwe.tex''
``````

(This is the top line of the buffer when I do `C-c C-l`.

Why on earth is aucTeX doing `"\input" mwe.tex` rather than just `mwe.tex`? What can this possibly achieve apart from causing my `%&custom` fmt definition to get ignored?

And secondly, where do I stop it doing this? I've looked at how the various commands mentioned above are defined. None of them seem to specify this behaviour. So what is actually causing this invocation of pdflatex?

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it may be related to the fact that when auctex began tex didn't have any command line arguments so you needed to do `tex \nonstopmode\input mwe.tex` to run a file in that mode. –  David Carlisle Aug 9 '12 at 15:58
@DavidCarlisle I see. I didn't know that. That makes the behaviour make sense, I guess. –  Seamus Aug 9 '12 at 16:00
I'm putting this as a comment and not an answer, since I don't have enough time now to write more, but look at the variables `TeX-command-list` and `TeX-expand-list`. (I was also dissatisfied with this default behavior and customized `TeX-command-list` to change it.) –  mbork Aug 9 '12 at 16:00
@mbork Aha! `TeX-expand-list` includes `%'` which expands to some complicated stuff that includes the dreaded `\input`. That's a pretty impressive way to obfuscate your option setting. Deleting `%'` from the right part of `TeX-command-list` seems to have done the trick. –  Seamus Aug 9 '12 at 16:06
@Seamus If you are still interested in the "Why on earth is aucTeX doing `"\input" mwe.tex` rather than just `mwe.tex`?" question, David Kastrup gave here an answer, more or less. –  giordano Feb 18 at 23:02
Thanks to `mbork` I found the answer. In `TeX-command-list` you get some pretty mystifying code soup:
``````%`%l%(mode)%' %t
Err. OK. The trick is that these things are defined in `TeX-expand-list`. One of these things, namely `%'` expands to a bunch of other stuff I don't understand but includes the `\input` that I wanted to get rid of. So deleting `%'` from the `LaTeX` part of `TeX-command-list` seems to fix things. I can't promise this is robust or that it won't cause problems somewhere down the line. If David Carlise is right that this `\input` is a throwback to before the `latex` command had command line options.