[texhax] undertilde and MiKTeX

[Peter Wilson]

On 27/10/17 22:05, Rolf Turner wrote:
>
> The journal of which I am Technical Editor provides a document class 
> file which implements the style conventions that papers published in the
> journal must meet.
>
> This document class makes use of the "\undertilde" command. Apparently 
> there are licensing issues with the undertilde package, and for this 
> reason (I think) my installation of texlive has no undertilde.sty file,
> but rather a file undertilde.tex.  Explicitly:
>
>  /usr/share/texlive/texmf-dist/tex/generic/genmisc/undertilde.tex
>
> For *that* reason the document class file for the journal uses
>
>     \input{undertilde}
>
> rather than
>
>     \usepackage{undertilde}
>
> An author contacted me just now saying that he is getting an error
>
>     > File `undertilde.tex' not found. \input{undertilde}
>
> This author is using TeXstudio which is a front end for MiKTeX.
>
> I have difficulty investigating this problem, since I
> *don't do Windoze* !!!  However some Googling indicates that MiKTeX 
> should indeed have access to undertilde.
>
> The curly is that one Google hit appears to indicate that MiKTeX 
> possesses undertilde.sty and another that it possesses undertilde.tex.
> These files would appear to live in
>
>    ...\texmf\tex\generic\genmisc
>
> (a) Can someone who uses Windoze/MiKTeX please confirm whether either 
> or both of the files undertilde.sty and undertilde.tex are present?  
> Where they should be?
>
> (b) It strikes me that it is possible that some releases of MiKTeX have
> undertilde.sty and some (older ones perhaps?) have undertilde.tex.
>
> If this is indeed the case I would like to be able to construct a 
> conditional input something along the lines of:
>
>   if(the file undertilde.sty is found) {
>       \usepackage{undertilde}
>   } else if(the file undertilde.tex is found) {
>       \input{undertilde}
>   } else {
>       Bail out with a message "undertilde not available"
>   }
>
> Can some clever person instruct me (monosyllabically; I'm a Bear of 
> Very Little Brain) as to how to construct such a conditional?
>
> Eternally grateful.
>
> cheers,
>
> Rolf Turner
>

Possibly like this (but beware of typos and missing {`s and/or }'s)
\documentclass{article}
\IfFileExists{fred.sty}%
     {\usepackage{fred}}%
     {\ClassWarning{article}{No file fred.sty}\IfFileExists{joe.tex}%
         {\input{joe}}%
         {\ClassWarning{article}{No file joe.tex}%
           \ClassError{article}{Files not found}{Missing files}%
}}
\begin{document}
Your text
\end{document}