Ubuntu 16.0.4 Latex is not showing section numbers?

For Ubuntu 16.0.4 just install the following from terminal:

sudo wget http://mirrors.ctan.org/macros/latex/contrib/titlesec/titlesec.sty -O /usr/share/texlive/texmf-dist/tex/latex/titlesec/titlesec.sty

 

Good luck!