Today, I found myself trying unsuccessfully to install something using tlmgr. The first problem was a missing compression/decompression program that was easy to install. After that, I continued to get cryptic error messages. Eventually, I decided to update tlmgr to see if that would help.
The Canonical (Ubuntu) repositories are fairly far behind the curve when it comes to TeX Live; they still provide the 2015 version, which is incompatible with newer versions (including the newer version of tlmgr). So updating tlmgr alone was not an option. (I had what appeared to be the most recent, and presumably final, incarnation of the 2015 version of tlmgr.) Following instructions I found on the Tips on Ubuntu site, I added a PPA containing the latest (I think) version of TeX Live, running the following in a shell:
sudo add-apt-repository ppa:jonathonf/texlive sudo apt update
After that, I used the software updater to update my TeX Live packages. (The "Tips on Ubuntu" instructions have you install TeX Live from the PPA, which presumes you do not already have a version installed, as I did.)
Before using tlmgr to do much of anything, you need to initialize the user tree by running
in a shell. I had already done that, but I repeated it, confirming that the user tree was still intact. I then ran
to open a graphical user interface, told it to load the default repository (there's a button in the "Repository" panel of the display), and tried -- unsuccessfully -- to install a LaTeX package.
So what was wrong now? The error message contained the following snippet:
Tk::Error: /usr/bin/tlmgr: open(/usr/share/texlive/tlpkg/texlive.tlpdb) failed: No such file or directory ...
I checked /usr/share/texlive/tlpkg, and sure enough there was no file texlive.tlpdb ... but there was a file named texlive.tlpdb.9ed73e8174b03a21aa0d40ebbcaac97f. It's a text file (around 12 MB) with configuration information and what looks like a directory structure. Why it had the rather funky hexadecimal extension, I have no idea. I symlinked it by running
sudo ln -s texlive.tlpdb.9ed73e8174b03a21aa0d40ebbcaac97f texlive.tlpdb
and tlmgr started behaving itself.
I later deleted the file with the scary looking hex extension, reran tlmgr and had it load the default repository again. It reproduced the file, but with a different (equally scary) hex extension. I again symlinked the file to texlive.tlpdb.
I have no idea why loading a repository produces what appears to be the correct file with the wrong extension and does not symlink it, but at least this fix seems to work.