fontconfig doesn't list/find XITS font even after updating config

Question

I would like to use XITS/XITS Math within my LaTeX project (which uses XeTeX). Following the answers to this question, I created a file /etc/fonts/conf.avail/76-texlive-fonts.conf with the following content:

<?xml version="1.0"?>
<!DOCTYPE fontconfig SYSTEM "fonts.dtd">
<fontconfig>
    <dir>/usr/share/texlive/texmf-dist/fonts/opentype</dir>
    <dir>/usr/share/texlive/texmf-dist/fonts/truetype</dir>
</fontconfig>

I had checked the above paths before to make sure that they are correct:

$ ls -l /usr/share/texlive/texmf-dist/fonts/opentype/public/xits
-rw-r--r-- 1 root root 111280 Nov 25  2016 xits-bolditalic.otf
-rw-r--r-- 1 root root 151692 Nov 25  2016 xits-bold.otf
-rw-r--r-- 1 root root 115536 Nov 25  2016 xits-italic.otf
-rw-r--r-- 1 root root 248956 Nov 25  2016 xits-mathbold.otf
-rw-r--r-- 1 root root 530128 Nov 25  2016 xits-math.otf
-rw-r--r-- 1 root root 249372 Nov 25  2016 xits-regular.otf

Afterwards, I added a symlink to /etc/fonts/conf.d/:

$ ls -l /etc/fonts/conf.d/76-texlive-fonts.conf 
lrwxrwxrwx 1 root root 35 Jan 10 13:15 /etc/fonts/conf.d/76-texlive-fonts.conf -> ../conf.avail/76-texlive-fonts.conf

…and ran $ fc-cache -fv. Its output, among others was:

/usr/share/texlive/texmf-dist/fonts/opentype/public/xits: caching, new cache contents: 6 fonts, 0 dirs

Still, when I run fc-list | grep -i xits now, there is no output and compiling the below MWE gives the following error, as expected:

…
main.tex:11: !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! [\setmainfont{XITS}]
main.tex:11: Font TU/XITS(0)/m/n/12=XITS at 12.0pt not loadable: Metric (TFM) file or installed font not found. [\setmainfont{XITS}]
…
main.tex:12: !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! [\setmathfont{XITS Math}]
main.tex:12: Font TU/XITSMath(0)/m/n/12="XITS Math/OT" at 12.0pt not loadable: Metric (TFM) file or installed font not found.
…

Here is the MWE:

\documentclass[12pt,a4paper]{article}

\usepackage{fontspec}
\usepackage{unicode-math}


\setmainfont{XITS}
\setmathfont{XITS Math}

\begin{document}
  Hello! Some math: $y = f(x)$

\end{document}

I would very much appreciate any pointers to how I could fix or at least debug this problem!

---

[UPDATE]: Turns out none of the fonts in /usr/share/texlive/texmf-dist/fonts/ show up in fc-list: The output of $ fc-list | grep /usr/share/texlive/texmf-dist/fonts is completely empty. Nevertheless, dozens of fonts get recognized when running sudo fc-cache -fv | grep /usr/share/texlive/texmf-dist/fonts. What is going on here?

Answer 1

I was being a moron: I ran fc-cache as root and fc-list as a regular user without realizing that the cache would then be built for the root user and not the regular user. Running both commands as regular user fixed the issue.

Answer 2

for xetex use the file names instead of the symbolic names:

\setmainfont{xits-regular.otf}
\setmathfont{xits-math.otf}
\setmathfont[version=bold]{xits-mathbold.otf}