Install Latex .sty and .cls files

Here is how to install a $\LaTeX$ physics.sty in Texlive under Ubuntu. You can do this to any other .sty package you like.

1. Downloaded the physics.sty files from the CTAN repo
2. As super user, create a directory in your $\LaTeX$ installation, mine is /usr/share/texmf-texlive/tex/latex
• sudo mkdir /usr/share/texmf-texlive/tex/latex/physics
3. Move the downloaded file to the new location
•  sudo mv physics.sty /usr/share/texmf-texlive/tex/latex/physics
4. Run  mktexlsr for changes to take effect
• sudo mktexlsr 
5.  Now start using it by adding the following to your  $\LaTeX$ file
• \usepackage{physics}
6. See the documentation on the package's web site for macro definitions
7. Happy  $\LaTeX$-ing