After seeing a discussion in steemit.chat I wanted to go back through and add some sources to my old posts. Since this one is too old to edit, I'm leaving them here in a comment.

The man pages for Bash and all of the other commands I've used above appear to cover 100% the stuff that I put in. If you're not on a Linux or *nix system where you can view man pages, here are the links to some online:

• Bash This does a decent job of explaining all of the built-in commands that I used (read, echo, while loops, for loops, parameter expansion). Some of the examples are pretty light, though. So I suggest googling some of the terms you might read in there to see examples on Stackoverflow.

• convert The convert man page does an okay job, but you'll probably want to check out the ImageMagick site for examples.

• readlink For discovering the path to a thing, I used it to get the absolute path to the script that was being run.

• find While technically this explains the command, most mortals will want to look for examples on Stackoverflow.