Installation

3 options:

1. To run from any folder, make the utility executable and move it to a folder in your $PATH:

$ chmod +x ~/Downloads/utility
$ mv -v ~/Downloads/utility /usr/local/bin
$ utility
Utility output!

2. Otherwise, make it executable, put it where you want, then call it by path:

$ chmod +x ~/Downloads/utility
$ mv -v ~/Downloads/utility /my/special/path/utility
$ /my/special/path/utility
Utility output!

3. If you don't want to make it executable or move it into your $PATH, you could just source it.
   This may not be a viable option in the future, so using an executable is preferred.

# `.` == `source`, use either
$ . /my/special/path/utility
Utility output!

Notes

macOS ships with an ancient (2007) version of Bash, so in order for these scripts to work you might need to get the latest from Homebrew, change the shebang to zsh, or run it in the current shell with source <file>.

Recent versions of macOS have zsh as the default interpreter/shell because Bash changed from GPLv2 to an even more open license – "GPLv3 is to Silicon Valley as garlic is to vampires". Without opening up their own software, Apple cannot distribute Bash 4.0+ with their OS.

Fun fact: /bin/sh is effectively a symlink to run /bin/bash --posix – it doesn't actually run the Bourne shell.

$ /bin/sh --version
GNU bash, version 3.2.57(1)-release (x86_64-apple-darwin23)
Copyright (C) 2007 Free Software Foundation, Inc.