Drive Link to pdf: https://drive.google.com/file/d/1HwG_Y0q8_UWSLWCjYGZ5fpmU5LpUZ5b-/view?usp=sharing

To learn more bash tricks, my fav website is tldp.org

They have awesome examples too. https://tldp.org/LDP/abs/html/manipulatingvars.html