Read file without file extension from hidden directory

Question

I'm trying to read some data from a file and use the following approach:

\documentclass{minimal}
\newcommand{\file}{./.dir/.testFile}
\begin{document}
\newread\myread
\openin\myread=\file\relax
\loop
  \read\myread to \data
  \unless\ifeof\myread
    \data
  \repeat
\closein\myread
\end{document}

This works for the following files (specified in the \file macro):

• testFile.txt --> Normal file
• dir/testFile.txt --> Normal file in folder
• .dir/testFile.txt --> Normal file in hidden folder
• .dir/.testFile --> Hidden file in hidden folder

But exactly the case which I need is not working: .dir/testFile. Why is it not possible to read a file without file extension and is there a way to get around this? Renaming the file is no option for me as the file is used/modified/created by another application. I need just the first line of the file, if this simplifies the problem in any way.

According to this question/answer, the extension .tex is always appended to the file name if no extension is given (even by using low-level commands). But I still think there must be a way to bypass this.

System:

• pdfTeX, Version 3.1415926-2.4.1.40.13
• MiKTeX 2.9 (Revision 2.9.4533, 32 bit)
• Windows 7 Professional (64 bit)

Answer 1

I don't have MiKTeX to test but it seems that extensionless files for input was fixed with this bug.

If \read wasn't fixed at the same time, the workaround should probably work: append a . to the end of the filename in the TeX call:

\newcommand{\file}{./.dir/testFile.}
                                  %

Answer 2

The problem arises, if you are using LuaTeX.

The source of the problem is that TeX tries the extension .tex for file names without extensions. Thus it seems that LuaTeX forces the extensions .tex if no extension is given. (A bug-report could be made.)

However, LuaTeX also supports an alternative syntax for specifying file names, similar to \pdfximage, the file name can be surrounded by braces, then the correct file is found:

\documentclass{minimal}
\newcommand{\file}{./.dir/testFile}
\begin{document}

\newread\myread
\openin\myread={\file}\relax
\loop
  \read\myread to \data
  \unless\ifeof\myread
    \data
  \repeat
\closein\myread
\end{document}

(Tested with LuaTeX 0.76.0 of TeX Live 2013.)