Setup

We’re going to use zsh as it is always available on any system I use:

#! /bin/zsh

We’ll want stricter defaults out of the box:

Option	Description
err_exit	Exit immediately if a command exits with a non-zero status.
no_clobber	Don’t allow > to truncate files
no_unset	Treat unset variables as an error.
warn_create_global	Warn when a global variable is created.

setopt err_exit no_clobber no_unset warn_create_global

We’ll need zutil to allow us to process command line arguments:

zmodload -F zsh/zutil +b:zparseopts