Three ways to use the Ruby executable

In the 90's and early 00's, when Ruby was starting to become popular, it was mostly as a language for sysadmins to write short scripts and CLI tools to automate their work. Ruby still maintains a lot of features and bells and whistles from this era, many of which are still very useful to Rails developers.Let's talk about three useful ways to use `ruby`, that is, the command line ruby executable. As Rails devs, we're pretty used to just using tools built with Ruby, but not actually running the Ruby executable itself. That's a shame - Ruby is a great CLI tool, and the executable has some cool features that are still useful for Rails devs today.