lualatex/xelatex: handling of stderr when using pipes

[mrpiggi]

Hi,
some context first. I am the developer of the LaTeX package svg which uses Inkscape CLI for automated conversion and import of SVG graphics into LaTeX documents. As Inkscape changed it's CLI from 0.9x to 1.0 I was encouraged to build an automatic version detection. Therefore I call inkscape -V during a LaTeX run through a pipe in order to read the returned string.

I recently discovered a problem reading from a pipe when both stdout and stderr are involved. This issue actually emerged as Inkscape v1.0.1 CLI currently uses stdout and stderr when returning inkscape -V. I already reported this issue.

However, I wanted to remark that MiKTeX has problems with handling stderr when reading pipes. First the MWE

\listfiles
\documentclass{minimal}
\usepackage[T1]{fontenc}
\begin{document}
\makeatletter
\@makeother\|%
\@makeother\&%
\everyeof{\noexpand}%

\edef\pipenormal{\@@input|"echo STDOUT && echo STDERR >&2 " }%
normal: \texttt{\pipenormal}

\edef\piperedirect{\@@input|"echo STDOUT && 2>&1 echo STDERR >&2 " }%
redirect: \texttt{\piperedirect}

\end{document}

The macro \pipenormal reads through a pipe and should expand to the message of stdout whereas \piperedirect redirects stderr to stdout and should expand to both messages. I checked this with TeX Live and it works as intended with all different formats (pdflatex, lualatex, xelatex). By contrast, MiKTeX generates different results for all three formats. Those are:

	normal	redirected
expected	STDOUT	STDOUT STDERR
pdflatex	STDOUT STDERR	STDOUT STDERR
lualatex	STDOUT STDERR	DOUT DERR
xelatex	STDERR	STDERR

[edocevoli]

I would recommend that you fix the expectations. Because echo STDOUT && echo STDERR >&2, on Windows, outputs:

STDOUT
STDERR

So the table must look like this:

	normal	redirected
expected	STDOUT STDERR	STDOUT STDERR
pdflatex	STDOUT STDERR	STDOUT STDERR
lualatex	STDOUT STDERR	DOUT DERR
xelatex	STDERR	STDERR

[mrpiggi]

echo STDOUT && echo STDERR >&2, on Windows, outputs:

STDOUT
STDERR

As well as Linux does. My expectations came from the behavior of TeX Live where stderr is suppressed/gobbled. But I'm totally fine with your call. Many thanks in avdance.

[mrpiggi]

Many thanks!

[edocevoli]

Thank you, this has been fixed. Please get the latest updates.

[mrpiggi]

Works like expected. Thanks again!