Very basic script that compares an Apple pkg with what's on disk

This is a really basic, really poor bash script for macOS that will compare a .pkg file with what's already on your disk. It's a quick and easy (cheesy?) way to tell what a package is installing or changing.

Basically, this script blindly trusts the package's BOM file, which could be wrong, and ignores any scripts that may perform further installation. (Some packages install all of their files by uncompressing a blob via a postinstall script.) There's also little to no error checking.

While it isn't perfect, it is generally great for Apple supplied packages, such as OS updates:

Apple Support Updates

To improve this script, there are several things that could be done:

• Take command-line arguments for debug-level, general verbosity, and granular reporting.
• Do more work for the user, such as mounting a DMG file, and then attacking the package inside.
• Analyze postinstall scripts

This script has been a nice tool for me for a few years, and I figured I'd finally share it. If you like it, great. I know it's far from perfect. If you do, too, pull requests are welcome.