TL 2024 cannot be installed on some Windows computers (again!)

[Zdenek Wagner]

ne 1. 12. 2024 v 1:31 odesílatel Bruno Voisin via tex-live
<tex-live at tug.org> napsal:
>
> ...
>
> In the TL doc, this is only mentioned about the changes for year 2019
>
>   https://tug.org/texlive/doc/texlive-en/texlive-en.html#x1-880009.1.16
>   https://www.tug.org/texlive/doc/texlive-fr/texlive-fr.html#x1-9400010.1.16
>
> So, on Unix-style systems (I'm on the Mac myself), this would be something like
>
>   TEXLIVE_PREFER_OWN=1 install-tl -gui
>
> I don't know how to achieve the same on Windows. I checked for a mention of that variable (or its effect) in the Advanced screen of the install GUI, there's none.
>
The environment setting in Windows persist, you just type
set TEXLIVE_PREFER_OWN=1

It will be used for all subsequent commands in the same "black
window", you can verify it by
echo %TEXLIVE_PREFER_OWN%

Or you can define it in user's environment in the system setting, it
will then be used forever until the user removes it. And it will be
used even in programs started from GUI. I am not sure whether it is
necessary to restart Windows after such change in the system setting,
I am not a Windows expert.

> Actually I wasn't aware of the above at all, found it the hard way by looking at the code. Inside the install package, there's texmf-dist/scripts/texlive/tlmgr.pl which on lines 7155 ff. delegates the task of locating the executables to a setup_programs variable, writing
>
>   # setup the programs, for w32 we need the shipped wget/xz etc, so we
>   # pass the location of these files to setup_programs.
>
> setup_programs is set in tlpkg/TeXLive/TLUtils.pm on lines 2890 ff., telling the OS utilities are preferred save for tar on Windows (the tar-specific code is on lines 2930 ff.).
>
> That's where TEXLIVE_PREFER_OWN comes in. Say the comments there:
>
>   If the C<$tlfirst> argument or the C<TEXLIVE_PREFER_OWN> envvar is set,
>   prefer TL versions; else prefer system versions (except for Windows
>   C<tar.exe>, where we always use ours).
>
> I don't know why the same is not done for xz as for tar (ie ensuring that the TL version is used on Windows). Maybe simply the problem wasn't widely known.
>
> Bruno
>
>

Zdeněk Wagner
https://www.zdenek-wagner.eu/