ls -l | wc -l ls: list directory contents -l: list in long format wc: word, line, character, and byte count -l: the number of lines is written to the standard output This command counts the number of listed lines.
detex my-document.tex | wc -w detex: a filter to strip TeX commands from a .tex file wc: word, line, character, and byte count -w: The number of words in each input file is written to the standard output