Install LaTex packages manually on Ubuntu

The following four steps permit manual installation of packages on Debian/Ubuntu (and presumably other Linux) systems.

If you have .sty file already, ignore step 1 and 2.

1. Download the package from CTAN (e.g., xCJKnumb.tar).
2. Extract the files and place them in an appropriate directory (e.g., /usr/local/share/texmf/tex/latex/xCJKnumb). This location is preferable to the main installation tree (/usr/share/texmf-texlive/tex/latex/) as the files are more likely to be preserved during upgrades.
3. Generate the .sty file by running latex on the appropriate source files (e.g., latex xCJKnumb.ins and latex xCJKnumb.dtx).
4. Update the ls-R file in this source tree (e.g., cd /usr/local/share/texmf/ ; sudo mktexlsr). Because /usr/local/share/texmf/tex/ is not searched recursively by kpathsea (cf. kpsepath tex), the ls-R file at the root directory of this search path must be updated to make the system aware of the new package.

References: 

1. https://en.wikibooks.org/wiki/LaTeX/Installing_Extra_Packages
2. http://emmanuel.rousseaux.me/blog_files/install-latest-latex-packages-within-the-tex-live-distribution-provided-by-ubuntu.html