or tlmgr install xxx --repository https://ftp.tu-chemnitz.de/pub/tug/historic/systems/texlive/2020/tlnet-final
repository
default: default package repository found in the installation's TeX Live Package Database (a.k.a. the TLPDB, which is given entirely in the file tlpkg/texlive.tlpdb (for example ~/texmf/tlpkg/texlive.tlpdb)
set in command line: tlmgr option repository https://mirror.ctan.org/systems/texlive/tlnet
set in configuration file: make a permanent change, use option repository (see the "option" action).
correct script error
First, edit TEXMFDIST/scripts/texlive/tlmgr.pl and replace $Master ="$Master/../.."; with $Master = "${Master}/../../..";. The path prefix TEXMFDIST is not a predefined environment variable, it is defined below in this article. Replace it with the correct value.
(base) [hongy19@CN-00000988 ~]$ tlmgr check files Files present but not covered (relative to /home/hongy19/texmf): tex/generic/pgf/tikzlibrarytimeline/tikzlibrarytimeline.code.tex web2c/tlmgr-commands.log web2c/tlmgr.log tlmgr.pl: An error has occurred. See above messages. Exiting.
(base) [hongy19@CN-00000988 ~]$ pacman -Qi texlive-core Name : texlive-core Version : 2021.61403-1
--package-logfile *file* "tlmgr" logs all package actions (install, remove, update, failed updates, failed restores) to a separate log file, by default "TEXMFSYSVAR/web2c/tlmgr.log". This option allows you to specify a different file for the log.
--command-logfile *file* "tlmgr" logs the output of all programs invoked (mktexlr, mtxrun, fmtutil, updmap) to a separate log file, by default "TEXMFSYSVAR/web2c/tlmgr-commands.log". This option allows you to specify a different file for the log.
when tlmgr running in user mode, log is stored in TEXMFHOME/web2c, not TEXMFSYSVAR/web2c
TEXMFDBS doesn't include TEXMFHOME which is searched for without ls-R files present. kpsewhich could still find document in TEXMFHOME
search document: kpsewhich -all markdown.sty
TLPDB (texlive.tlpdb)
tlpdb stands for tex live package data base, it is the main control file for the texlive package installation, it lists every package in texlive and whether you have it installed or not, which texlive mirror repository you use and lots of other details. The texlive installation seems broken if it is not there
texlive.tlpdb on ctan is no use, the file is a local file that records which packages are installed on that machine it should be