[tex-k] [MacTeX] Update TL2020

[Andreas Scherer]

Dear list,

After updating MacTeX (BasicTeX) to TeX Live 2020 by hand successfully,
I would now like to change the root directory from
/usr/local/texmf/2019basic to /usr/local/texmf/2020basic just for
consistency.

The upgrade was done via 'tlmgr', because for administrative reasons I'm
stuck with MacOS 10.12, so the BasicTeX2020.pkg doesn't work.

Consulting http://www.tug.org/mactex/BasicTeX.pdf lead to the download
of https://tug.org/svn/texlive/trunk/Master/install-tl?view=log and the
invocation 'sudo ./install-tl' in /usr/local/temf/2020basic (after
backup and renaming of the full install path).

However, as the attached screenshot shows, the "TeX Live
Installationsprogramm" still refers to "2019" both in its name and in
the "Stammverzeichnis" (root directory), although the script itself
appears to be from Sun May 31 20:09:55 2020 UTC.  Clicking on "Ändern"
(Change) only provides the option to remove the year, not to change it
to another value.

Clicking on "Fortgeschritten" (Advanced?) leads to the crash depicted in
the shell window in the screenshot.

My question: Is there a way to change $TEXDIR to
/usr/local/texmf/2020basic so that tlmgr, kpsewhich, and the other
binaries actually work from there?

Thanks in advance,
Andreas