Mac
From charlesreid1
Excellent command line utilities for the mac: Mac/Command Line
New Mac installation procedure for Sierra
New Mac installation procedure for Yosemite
New Mac installation procedure for Lion
Beginner's guide to setting up a dev env on a mac: https://github.com/nicolashery/mac-dev-setup
Note if you are changing a user's shell: https://superuser.com/questions/379725/how-do-i-change-a-users-default-shell-in-osx/379726
If you are trying to recover a Mac that has problems: Mac/Recovery