Data Science at the Command Line

Chapter 4. Creating Reusable Command-Line Tools

Throughout the book, we use a lot of commands and pipelines that basically fit on one line (let’s call those one-liners). Being able to perform complex tasks with just a one-liner is what makes the command line powerful. It’s a very different experience from writing traditional programs.

Some tasks you perform only once, and some you perform more often. Some tasks are very specific and others can be generalized. If you foresee or notice that you need to repeat a certain one-liner on a regular basis, it’s worthwhile to turn this into a command-line tool of its own. Both one-liners and command-line tools have their uses. Recognizing the opportunity requires practice and skill. The advantage of a command-line tool is that you don’t have to remember the entire one-liner and that it improves readability if you include it into some other pipeline.

The benefit of working with a programming language is that you have the code in a file. This means that you can easily reuse that code. If the code has parameters it can even be applied to problems that follow a similar pattern.

Command-line tools have the best of both worlds: they can be used from the command line, accept parameters, and only have to be created only once. In this chapter, we’re going to get familiar with creating reusable command-line tools in two ways. First, we explain how to turn one-liners into reusable command-line tools. By adding parameters to our commands, we can add ...