Data Science at the Command Line, 2nd Edition

Chapter 4. Creating Command-Line Tools

Throughout the book, I’ll introduce you to many commands and combinations of commands that basically fit on one line. These are known as one-liners or pipelines. 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 and using traditional programs.

Some tasks you perform only once, and some you perform more often. Some tasks are very specific, while others can be generalized. If 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. So both one-liners and command-line tools have their uses. Recognizing the opportunity to turn a one-liner or existing code into a command-line tool requires practice and skill. The advantages of a command-line tool are that you don’t have to remember the entire one-liner and that it improves readability if you include it into some other pipeline. In that sense, you can think of a command-line tool as similar to a function in a programming language.

The benefit of working with a programming language, however, is that the code is in one or more files. This means that you can easily edit and reuse that code. If the code has parameters, it can even be generalized and reapplied to problems that follow a similar pattern.

Command-line tools have the best of both worlds: they can be used from the command line, they accept parameters, and they have to be created ...