Write to a file outside of the current folder

Question

Is it possible with TeX to write somewhere else than in the current folder?

The following does not work:

\documentclass{article}
\begin{document}

\newwrite\tempfile
\openout\tempfile=/Users/colas/Desktop/coucou.aux
\write\tempfile{Test}
\closeout\tempfile

Test

\end{document}

The error is

./bac_a_sable.tex:13: I can't write on file `/Users/colas/Desktop/coucou.aux'. \endgroup \set@typeset@protect l.13 \end{document}

Answer 1

TeX Live (which I'm guessing you're using) normally doesn't allow file write operations outside of the current directory path because it's a security risk. This is governed by the openout_any setting, which may take one of three values (information copied from texmf.cnf):

• a (any) : any file can be opened.
• r (restricted) : disallow opening dot files
• p (paranoid) : as r and disallow going to parent directories, and restrict absolute paths to be under $TEXMFOUTPUT.

Normally the setting is p, which doesn't allow going to parent directories. I really don't recommend changing this setting.

You might want to consider changing $TEXMFOUTPUT to the target directory (since you're using an absolute path), which should then be allowed write access under TeX (if the filing system permits it), but I think David's comment is better:

it is far safer to keep the security setting but make a symbolic link in the current directory to your global file so you can write that file with a local path

If you are absolutely sure that you want to lower the security settings, you can change your preferred setting in your texmf.cnf file. But I really don't recommend it.