Introduction

Good tools matter!

xkcd-1168 — source: xkcd.com license: CC BY-NC 2.5

Why CLIs

A well-done CLI is the best format to build a tool, because the CLI can be used on its own to build any other type of tool, and it provides a direct and explicit separation of responsibilities between combinations and compositions of tools. For example, a GUI is then built up by first creating a good CLI tool that does the actual work of the program, and the GUI is only built around providing a good UI for the user while calling the CLI behind the scenes to handle the requests and visualize the responses. This means the GUI never has to be concerned with the business logic of the CLI, and the CLI never has to be concerned with the UI and display of the tool to the user.