Is there a way to detect from inside a package that MiKTeX is used?

Question

Is there a way to detect that the MiKTeX TeX LaTeX executable is used? Something like \ifmiktex or even \IfFileExists{<some file only present in MiKTeX>}{}{}?

The reason is that in one of my packages I have to re-execute LaTeX internally on an different .tex file, which of course requires the shell escape aka. write18 feature to be enabled by the user. However, I want to support this feature recursively, i.e. the other .tex file can itself call an own LaTeX sub-process. For this to work I have to add the correct command line option to the internally call of the (pdf)latex executable. Now this option is -shell-escape for TeXLive, but --enable-write18 for MiKTeX.

Here some example code how I plan to implement this feature. The missing part is the definition of \ifmiktex.

\ifpdf
   \def\latexcmd{pdflatex }%
\else
   \def\latexcmd{latex }%  
\fi

\ifmiktex
   \immediate\write18{\latexcmd --enable-write18 \options \file}%
\else
   \immediate\write18{\latexcmd -shell-escape \options \file}%
\fi

Answer 1

MiKTeX supports both optional arguments --enable-write18 and also --shell-escape

a possible Test for MiKTeX

\documentclass{article}

\newif\ifMiKTeX
\makeatletter
\def\testMiKTeX{\expandafter\testMiKTeX@i\pdftexbanner\@nil}
\def\testMiKTeX@i#1(#2)#3\@nil{\testMiKTeX@ii#2..\@nil}
\def\testMiKTeX@ii#1.#2.#3\@nil{\ifx\relax#2\relax\else\MiKTeXtrue\fi}
\makeatother
\testMiKTeX

\begin{document}

\ifMiKTeX we use MiK\TeX \else we use \TeX Live\fi

\end{document}

Answer 2

Here a general proof-of-concept solution which provides \ifmiktex and \iftexlive switches. It is based on Herberts suggestion to use the output of \pdftexbanner. Once finished, it could be published as, say ifdist package or similar.

Please note that the \pdftexbanner expands to text with catcode "other", therefore \@onlevel@sanitze is used to also give the macro parameter text the same catcode.

---

Update 2012/05/05:

Reworked and tested the code for Tex Live Linux, TeX Live Windows and MiKTeX. Provided warning for XeLaTeX which is not supported. I put it in the form of a package. Will Robertson might integrate it into ifplatform.

\ProvidesPackage{ifdistro}[2012/05/05 v1.0 Provides if-switches for MiKTeX and TeX Live]

\newif\ifmiktex
\newif\iftexlive

\begingroup
\makeatletter
\def\MiKTeX{MiKTeX}
\@onelevel@sanitize\MiKTeX
\def\TeXLive{TeX Live}
\@onelevel@sanitize\TeXLive
\def\WebIIC{Web2C}
\@onelevel@sanitize\WebIIC

% Test if \pdftexbanner exists, which is the case for latex, pdflatex and lualatex
% but not xelatex.
\expandafter\ifx\csname pdftexbanner\endcsname\relax
    \PackageWarning{ifdistro}
        {Primitive \string\pdftexbanner\space not found!\MessageBreak
         Switches \expandafter\string\csname ifmiktex\endcsname\space 
         and \expandafter\string\csname iftexlive\endcsname\space 
         will not be set\@gobble}% gobbles the "on line X" part
\else

% Scans for 'MiKTeX' string with catcode 12 (other)
\expandafter\def\expandafter\testmiktex\expandafter#\expandafter1\MiKTeX#2\relax{%
        \ifx\empty#2\empty
             \global\miktexfalse
        \else
             \global\miktextrue
        \fi
}
\expandafter\expandafter
\expandafter\testmiktex\expandafter\pdftexbanner\MiKTeX\relax\relax
\ifmiktex\else
% Scans for 'TeX Live' string with catcode 12 (other)
\expandafter\def\expandafter\testtexlive\expandafter#\expandafter1\TeXLive#2\relax{%
        \ifx\empty#2\empty
             \global\texlivefalse
        \else
             \global\texlivetrue
        \fi
}
\expandafter\expandafter
\expandafter\testtexlive\expandafter\pdftexbanner\TeXLive\relax\relax
\iftexlive\else
% Scans for 'Web2C' string with catcode 12 (other)
% This string is used by TeX Live under MS Windows
\expandafter\def\expandafter\testtexlive\expandafter#\expandafter1\WebIIC#2\relax{%
        \ifx\empty#2\empty
             \global\texlivefalse
        \else
             \global\texlivetrue
        \fi
}
\expandafter\expandafter
\expandafter\testtexlive\expandafter\pdftexbanner\TeXLive\relax\relax
\fi\fi

\fi

\endgroup

Answer 3

One good approach is to test whether a particular application exist or not. For example, if Yap (dvi viewer of MiKTeX) exists, you know that you are using MiKTeX. This approach has a good advantage that works with any other engine but the disadvantage is that write18 should be enabled.