How to specify the path to texlive in lyx?

Question

At work I have a centOS computer, which runs an outdated version of texlive. A texlive developer recomends installing the upstream version in this CentOS forum. I installed the 2018 version of texlive. It has several path locations:

    <D> set directories:
   TEXDIR (the main TeX directory):
     !! default location: /usr/local/texlive/2018
     !! is not writable or not allowed, please select a different one!
   TEXMFLOCAL (directory for site-wide local files):
     /usr/local/texlive/texmf-local
   TEXMFSYSVAR (directory for variable and automatically generated data):
     /usr/local/texlive/2018/texmf-var
   TEXMFSYSCONFIG (directory for local config):
     /usr/local/texlive/2018/texmf-config
   TEXMFVAR (personal directory for variable and automatically generated data):
     ~/.texlive2018/texmf-var
   TEXMFCONFIG (personal directory for local config):
     ~/.texlive2018/texmf-config
   TEXMFHOME (directory for user-specific files):
     ~/texmf

Now I would like Lyx to point to the new texlive version.

This question explains how to change the Tools / Preferences / Paths on windows. It did change Tools / Preferences / Paths / path prefix to "/usr/local/texlive/2018/", but Lyx seems to be still using the old path configuration. See screenshot:

I guess there is another way to tell Lyx which version of TexLive to use?

Answer 1

If TeX Live is well installed, simply use the Rescan button that you show in the image, then go to Tools > Reconfigure.

After some time a message will warn you about restart LyX. Do that and now it should work with the 2018 version.

BTW, yo do not need add /usr/local/texlive/2018/ to any path in Preferences, but first, in a terminal, be sure that echo $PATH show /usr/local/texlive/2018/bin/x86_64-linux.