Unix was created in Bell Labs (part of AT&T) by Ken Thompson, Dennis Ritchie and others. BSD (Berkeley Software Distribution) was based on it which Apple then modified it to make MacOS.

By Eraserhead1, Infinity0, Sav_vas - Own work using: Levenez Unix History Diagram, Information on the history of IBM's AIX on ibm.com, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=1801948

chmod: 1 x, 2 w, 3 xw, 4 r, 5 rx, 6 rw, 7 rwx

alias ll=”ls -FAGhl —group-directories-first —time-style=long-iso —color”

kill -9 $(pgrep node | awk '$1>4500') - Kills all processes called node with PID higher than 4500