[tldoc] suggestions for the doc section 3.4.5 context lmtx and mkiv

[Carlos]

On 2/23/23 17:37, Karl Berry wrote:
> Hi Carlos,
> 
>      I had some issues with the the way by which namely, context, and the
>      scripts used therein handles any call with a file.
> 
> I admit I'm not sure at what level the problem you're discussing is. 

I'm not sure either. I'm not. I thought of TeX Live documentation, 
mainly  (believe it not), after spending quite a while frustrated while 
trying to keep up with a recurring issue, and it was through the manual 
indeed which seemed to resolve it But the problem shouldn't have been 
there in the first place.
If
> some specific change to the TL manual that would help, please draft
> something and let me know.
> 
> In general, we cannot document detailed/exact ConTeXt (or anything else)
> behavior in the TL manual, especially wrt what envvars are used or not
> used, how they conflict, etc. It has to be left to the documentation of
> the formats/programs. If it's not documented there, we can't solve that.

I wish I could draft just an excerpt for this. I wish. A suggestion for 
a solution that is, that would tackle the source, and bypassing envvars
> 
> If you think ConTeXt should behave differently, the change needs to be
> sent to the ConTeXt developers. --best, karl.
> 

Sorry Karl. But I'm not here to tell them what they must do. I'm more 
concerned with the tl guide than anything else, really. Don't forget 
that it was solely by going over the tl guide  by which the issue was 
resolved in my end. I had given up with this.

But let's go over the following.

If you were to go over this fragment on the tl guide that says

\dirname{TEXMFVAR} is the location for storing most cached runtime data
specific to each user.  \dirname{TEXMFCACHE} is the variable name used
for that purpose by Lua\LaTeX\ and \ConTeXt\ MkIV (see
section~\ref{sec:context-mkiv}, \p.\pageref{sec:context-mkiv}); its
default value is \dirname{TEXMFSYSVAR}, or (if that's not writable),
\dirname{TEXMFVAR}.


Both LuaLaTeX and ConTeXt are included. Correct?

And it clearly says that the default value for ConTeXt is TEXMFSYSVAR

It would not be surprising at all then, to find out that LuaLaTeX simply 
does not seem affected at all by this issue, does it? and for a good 
reason: presumably because of the kpathsea library.

But I genuinely can't remember if it ever happened with LuaTeX, and if 
it did, I missed it, but with ConTeXt (whether standalone or not) this 
is a recurring event. Give or take a handful of years, add or subtract a 
couple of them in between. It's a cycle Karl. A cycle.

Anyway. Here's a possible draft for the doc, and from what I've seen 
after breaking down my own system with this very same issue.

diff --git a/texlive-en.tex b/texlive-en.tex
index 6c7c572..09b2529 100644
--- a/home/ce/Downloads/texlive-en.tex
+++ b/texlive-en.tex
@@ -1187,6 +1187,10 @@ for LMTX, and
  \begin{sverbatim}
  context --luatex --generate
  \end{sverbatim}
+or
+\begin{sverbatim}
+mtxrun --generate
+\end{sverbatim}
  for MkIV, to refresh the \ConTeXt{} disk cache data.
  The resulting files are stored under \code{TEXMFCACHE},
  whose default value in \TL\ is \verb+TEXMFSYSVAR;TEXMFVAR+.
@@ -1196,6 +1200,18 @@ all paths mentioned in \verb+TEXMFCACHE+, and 
write to the first
  path that is writable. While reading, the last found match will
  take precedence in the case of duplicated cache data.

+It is recommended for the stored cache data on \ConTeXt\ to be
+written under \code{TEXMFVAR} preferably over \code{TEXMFSYSVAR}.
+
+Duplicate cache data on both \code{TEXMFVAR} and \code{TEXMFSYSVAR}
+could create a conflict while generating and updating the formats. This
+may result in an error such as:
+
+\verb+mtxrun | unknown script `context.lua' or `mtx-context.lua'+
+
+The \dirname{luatex-cache} directories under both \code{TEXMFVAR} and
+\code{TEXMFSYSVAR} would normally hold the duplicate runtime data cache.
+
  For more information, see \url{https://wiki.contextgarden.net/LMTX}\\
  and \url{https://wiki.contextgarden.net/Running_Mark_IV}.



take care Karl.