Before we start, it is a good idea to try and understand the difference between biblatex and BibTeX. bibtex vs. biber and biblatex vs. natbib has some explanations that should make the difference between the two clearer, so just quickly: BibTeX is a program that extracts bibliography data from a .bib file and processes the data with the help of .bst files ('BibTeX styles') into LaTeX-readable data. More generally, sometimes people (I certainly) say 'BibTeX' when they mean the whole bibliography setup that comes with using BibTeX with .bst files. biblatex is a LaTeX package for citations and bibliographies that works differently from the 'BibTeX approach'. biblatex can be used with BibTeX and the newer Biber as 'backends' that extract the relevant entry data from the .bib file.
When you want to use
\usepackage[<options>]{biblatex}
in your document, you are using biblatex.
When you are loading biblatex with the option backend=bibtex,, then you are using biblatex with the BibTeX backend.
That means you need both biblatex and BibTeX to be properly installed on your system.
The first message
I couldn't open style file biblatex.bst
---line 6 of file myDoc.aux
: \bibstyle{biblatex
: }
I'm skipping whatever remains of this command
I found no style file---while reading file myDoc.aux
you get suggests BibTeX is up an running (the message comes from BibTeX), but biblatex does not appear to be fully installed. In particular the file biblatex.bst (available from https://ctan.org/tex-archive/macros/latex/contrib/biblatex/bibtex/bst on CTAN) does not appear to be installed correctly.
According to your directory listings you have
./tex/latex/biblatex/bibtex/bst:
biblatex.bst
but the file should live in
./bibtex/bst/biblatex
The correct path here is crucial since the file will not be found correctly by kpsewhich if it resides elsewhere. (The path specifications are known as TDS: http://tug.ctan.org/tds/tds.html. Technically, only the ./bibtex/bst/ bit of the path is crucial, the rest after that is arbitrary, but it is a good idea to keep your directories organised with subdirectories.)
This is one of the perils of installing packages manually from CTAN: For complex packages you might get the directory structure wrong. That's why some packages come with a .tds.zip, where the TDS structure is already correctly represented in the .zip and you only need to unpack everything into your TEXMFHOME.
Another issue with manual installations from CTAN is package compatibility. The version you get from CTAN is the newest version of the package. The new biblatex version may rely on other packages being similarly up-to-date. So if you install one package manually, you may end up having to update or install several other packages manually as well to make sure that versions match.
Since you installed your TeX Live from the software repositories of your Linux distro, it may be possible to properly install biblatex via your Linux distro as well. Unfortunately, I'm not really familiar with CentOS and don't know which version of TeX Live CentOS 7 ships. But firing up yum's search function to look for biblatex can't hurt.
If the TeX Live shipped by your Linux distribution in its repositories is hopelessly outdated or packages you need are not available, you may want to consider installing a 'vanilla' TeX Live from TUG.org. (Instructions for Ubuntu are at How to install "vanilla" TeXLive on Debian or Ubuntu?. Generic instructions at https://tug.org/texlive/acquire-netinstall.html.)
Assuming your biblatex installation is complete and compatible with all packages on your installation,
\usepackage[backend=bibtex,style=plain]{biblatex}
\addbibresource{myBib.bib}
is still not quite right. You are telling biblatex to use a style called plain, but biblatex doesn't know a style of that name. biblatex has its own system of defining bibliography and citation styles that doesn't use BibTeX's .bst files. If plain was meant to refer to the BIbTeX style plain.bst it simply cannot be used with biblatex. (As we have seen, biblatex needs biblatex.bst when it is used with BibTeX. That file is always used no matter what biblatex style you request.)
You need to pick one of biblatex's own styles. The available standard styles are listed in the biblatex documentation and further custom styles are available on CTAN: https://www.ctan.org/topic/biblatex. For example
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}
\usepackage[backend=bibtex,
style=authoryear,
]{biblatex}
\addbibresource{biblatex-examples.bib}
\begin{document}
Lorem \autocite[380]{sigfridsson}
ipsum \autocite[cf.][]{nussbaum}
dolor \autocite{worman}
sit \autocite[cf.][41]{geer}
\printbibliography
\end{document}
If you don't want to use biblatex at all and just want to use standard BibTeX instead, your document would look like the following
\documentclass[british]{article}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\begin{document}
Lorem \cite[380]{article-full}
ipsum \cite{incollection-full}
dolor \cite{inproceedings-full}
sit \cite[41]{inbook-full}
\bibliographystyle{plain}
\bibliography{xampl}
\end{document}
Note that nowadays it is recommended to use Biber as backend for biblatex instead of BibTeX. Only Biber allows you to make use of all of biblatex's advanced features. But Biber needs to be available on your system and must be installed in a version that is compatible with your biblatex version.
apt-filefeature as I can ask it to tell me where saysiunitx.styis. Then I can just install that Ubuntu package. Centos probably has something similar. – daleif Sep 16 '20 at 13:06bibtexwas in myyumrepository, I would have installed it withyum! And concerningtux.org/texlive, it looks even more complicated, as I can't find (and install withyum)tlmgron my system! – Phantom Sep 17 '20 at 07:11tlmgras they want you to install the various latex packages via yum instead. Note thatbiblatexis not the same asbibtexand will generally usebiberinstead so again you will need to figure out how to determine which yum packages you need to install. At least in Ubuntu there is a meta package calledtexlive-fullwhich will install all available Ubuntu texlive packages. Also note that installing the upstream texlive has nothing to do withtlmgr. – daleif Sep 17 '20 at 07:40biblatex, notbibtex. I installed latex viatexlive-fullbyyum. Yes CentOS 7 is old, that's why lot of Latex packages are missing, but I had no choice on the system :( – Phantom Sep 17 '20 at 07:58biblatexdepends on many other packages. – daleif Sep 17 '20 at 08:03