bashrc bash_profile zprofile zshrc etc.

- https://apple.stackexchange.com/questions/388622/zsh-zprofile-zshrc-zlogin-what-goes-where
- https://stackoverflow.com/questions/415403/whats-the-difference-between-bashrc-bash-profile-and-environment
- https://superuser.com/questions/789448/choosing-between-bashrc-profile-bash-profile-etc