This week I picked up the book Build Awesome Command-Line Applications in Ruby 2, which you can find here. I have always been a huge fan of the command line and since I really enjoy writing Ruby applications this book seemed like a double winner.

I am about half way through and so far I am totally digging this book! The author has done a great job explaining the expected structure and functionality any command line style application should have. It gives some good examples of designing and developing two different kinds of applications.

The first example covers a simple application that can back up databases for you in an iteration fashion. The example introduces a couple handy Ruby libs that are recommended when building your own application and they are Open3 and OptionParser. I found both of these standard libs that come with Ruby extremely handy. OptionParser gives you a great way to parse flags and switches that your application may use and also gives you an added benefit of getting your foot in the door to supplying documention with the default —help switch. Open3 provides a way to capture the standard and error output streams as well as the exit code status of another application that is started by your code.

The second example provided by the book is a todo list application. The nature of this application is a bit beefy and is refered to as an application suite. An application suite has takes the following format …

 app_name [global_options] action [action_options] arguments...

The application is broken down into smaller sub-applications that are called out by the “action” portion. Perhaps one of the greatest examples of this is Git. The author details out a couple different open source libraries that you can use to build a suite and they are…

• Commander
• Thor
• GLI

If you are at all interested in this book I would pick it up and give it a read. I’ll make another post and sum up the whole book when I finish it, peace for now!