Finding out if I've Improved as a Programmer: Part 3

I've been walking through one of my old college projects of a shell program in an effort to see how much I've improved as a programmer over the past however many years. So far this exercise has been pretty enlightening, and I hope to finish it up in this post. I've improved the formatting and added a better set of automated tests to the project, and I've made it part way through what originally was the only function in the simple shell program, main(), refactoring as I went. Now we're at the main loop of the program that reads in and executes the commands. I've tried to be as brutally honest as I can in assessing the faults of my old coding style, and I'll keep that up as we finish this out. Let's dive right in and see how to clean up the rest of the code. As before, you can follow along with my GitHub repo to see all of the refactorings in context.