% \subsection{texsys.cfg}
%
% This file contains the site specific definitions of the four macros\\
% |\@currdir|, |\input@path|, |\filename@parse| and |\@TeXversion|.
%
% As distributed it only contains comments, however this `empty'
% file will work on many systems because of the automatic tests built
% into |ltdirchk.dtx|. You \emph{are} allowed to edit this file to add
% definitions of these macros appropriate to your system.
%
%
% The macros that must be defined are:
%
% \DescribeMacro{\@currdir}
% |\@currdir|\meta{filename}\meta{space} should expand to a form of the
% filename that uniquely refers to the `current directory' if this is
% possible. (The expansion should also end with a space.) on UNIX,
% this is |\def\@currdir{./}|. For more exotic operating systems you may
% want to make |\@currdir| a macro with arguments delimited by |.|
% and/or \meta{space}. If the operating system has no concept of
% directory structure, this macro should be defined to be empty.
%
%
% \DescribeMacro{\input@path}
% If the primitive |\openin| searches the same directories as the
% primitive |\input|, then it is possible to tell (using |\ifeof|)
% whether a file exists before trying to input it. For systems like
% this, |\input@path| should be left undefined.
%
% If |\openin| does not `follow' |\input| then |\input@path| must be
% defined to be a list of directories to search for input files. The
% format for each directory is as for |\@currdir|, normally just a
% prefix is required, but it may be a macro with space-delimited
% argument. That is, if \meta{dir} is an entry in the input path,
% \TeX will try to load the expansion of
%
%   \meta{dir}\meta{filename}\meta{space}
%
% So either \meta{dir} should be defined as a macro with argument
% delimited by space, or it should just expand to a directory name,
% including the final directory separator, so that it may be
% concatenated with the \meta{filename}. This means that for UNIX-like
% syntax, each \meta{dir} should end with a slash, |/|. One exception to
% this rule is that the input path should \emph{always} contain the
% empty directory |{}| as this will allow `full pathnames' to be used,
% and the  `current directory' to be searched.
%
% |\input@path| should expand to a list of such directories, each in a
% |{}| group.
%
%
% \DescribeMacro{\filename@parse}
% After a call of the form: |\filename@parse{|\meta{filename}|}|, the
% three macros |\filename@area|,|\filename@base|,|\filename@ext| should
% be defined to be the `area' (or directory), basename and
% extension respectively. If there was no extension specified in
% \meta{filename}, |\filename@ext| should be |\let| to |\relax| (so this
% case may be tested with |\@ifundefined{filename@ext}| and, perhaps a
% default extension substituted).
%
% Normally one would not need to define this macro in |texsys.cfg| as
% the automatic tests can supply parsers that work with UNIX and VMS
% syntax, as well as a basic parser that willcover many other cases.
% However some operating systems may need a `hand produced' parser
% in which case it should be defined in this file.
%
% The UNIX parser also works for most MSDOS \TeX\ versions.
% Currently if the UNIX or VMS parser is not used, |\filename@parse| is
% defined to always return an empty area, and to split the argument into
% basename and extension at the first `|.|' that occurs in the name.
% Parsers for other formats may be defined in |texsys.cfg|,
% in which case they will be used in preference to the default
% definitions.
%
%
% \DescribeMacro{\@TeXversion}
% You should not need to set this macro in |texsys.cfg|. \LaTeX\
% tests to set this automatically. See the comments in the opening
% section of \texttt{ltdirchk.dtx}.
%
%
% The following sections give examples of definitions which might
% work on various systems. These are currently mainly untested as I only
% have access to a few systems, all of which do not need this file as
% the automatic tests work. All the code is commented out.
%
% \subsection{UNIX (web2c)}
% This implementation does make |\openin| and |\input| look in the same
% places. Acceptable settings are made by |ltdirchk.dtx|, and so this
% file may be empty. The definitions below are therefore just for
% information.
%    \begin{macrocode}
%\def\@currdir{./}
%\let\input@path\@undefined
%    \end{macrocode}
%
% \subsection{UNIX (other)}
% Apparently some commercial UNIX implementations have different paths
% for |\openin| and |\input|. For these one could use definitions like
% the following (with whatever directories are used at your site):
% note that the directory names should end with |/|.
%    \begin{macrocode}
% \def\@currdir{./}
% \def\input@path{%
%   {/usr/local/lib/tex/inputs/distrib/}%
%   {/usr/local/lib/tex/inputs/contrib/}%
%   {/usr/local/lib/tex/inputs/local/}%
% }
%    \end{macrocode}
%
% \subsection{MSDOS (emtex)}
% This implementation does make |\openin| and |\input| look in the same
% places. Acceptable settings are made by |ltdirchk.dtx|, and so this
% file may be empty. The definitions below are therefore just for
% information.
%    \begin{macrocode}
% \def\@currdir{./}
% \let\input@path\@undefined
%    \end{macrocode}
%
% \subsection{MSDOS (other)}
% Some PC implementations have different paths
% for |\openin| and |\input|. For these one could use definitions like
% the following (with whatever directories are used at your site):
% note that the directory names should end with |/|.
% This assumes the implementation uses UNIX style |/| as the directory
% separator.
%    \begin{macrocode}
% \def\@currdir{./}
% \def\input@path{%
%   {c:/tex/inputs/distrib/}%
%   {c:/tex/inputs/contrib/}%
%   {c:/tex/inputs/local/}%
% }
%    \end{macrocode}
%
% \subsection{VMS (DECUS \TeX, PD VMS 3.6)}
% This implementation does make |\openin| and |\input| look in the same
% places. Acceptable settings are made by |ltdirchk.dtx|, and so this
% file may be empty. The definitions below are therefore just for
% information.
%    \begin{macrocode}
% \def\@currdir{[]}
% \let\input@path\@undefined
%    \end{macrocode}
%
% \subsection{VMS (???)}
% Some VMS implementations have different paths
% for |\openin| and |\input|. For these one could use definitions like
% the following:
%    \begin{macrocode}
% \def\@currdir{[]}
% \def\input@path{%
%   {tex_inputs:}%
%   {SOMEDISK:[SOME.TEX.DIRECTORY]}%
% }
%    \end{macrocode}
%
% \subsection{MACINTOSH (OzTeX 1.6)}
% This implementation does make |\openin| and |\input| look in the same
% places. Acceptable settings are made by |ltdirchk.dtx|, and so this
% file may be empty. The definitions below are therefore just for
% information.
%    \begin{macrocode}
% \def\@currdir{:}
% \let\input@path\@undefined
%    \end{macrocode}
%
% \subsection{MACINTOSH (other)}
% Some Macintosh implementations have different paths
% for |\openin| and |\input|. For these one could use definitions like
% the following (with whatever folders are used on your machine):
% note that the directory names should end with |:|, and they should
% contain {\em no\/} spaces.
%    \begin{macrocode}
% \def\@currdir{:}
% \def\input@path{%
%   {Hard-Disk:Applications:TeX:TeX-inputs:}%
%   {Hard-Disk:Applications:TeX:My-inputs:}%
% }
%    \end{macrocode}
%
% \subsection{FAKE EXAMPLE}
%  This example is for an operating system that has filenames of the
%  form |<area>name|  For maximum compatability with macro sets,
%  you want |name.ext| to be mapped to |<ext>name|.
%  and |<area>name.ext| to be mapped to |<area.ext>name|.
%  |\input| does this mapping automatically, but |\openin| does not, and
%  does not look in the same places as |\input|.
%  |<>name| is the desired `current directory' syntax.
%
% the following code would possibly work:
%    \begin{macrocode}
% \def\@dir#1#2 {%
%   \@d@r{#1}#2..\@nil}
% \def\@d@r#1#2.#3.#4\@nil{%
%   <\ifx\@dir#1\@dir\else#1\ifx\@dir#3\@dir\else.\fi\fi#3>#2 }
%
% \def\@currdir{\@dir{}}
% \def\input@path{%
%   {\@dir{area.one}}%
%   {\@dir{area.two}}%
% }
%    \end{macrocode}