Create a CLI tool with Node: a simple example

Let's build the simplest CLI tool; create a folder called HelloWorld and include 2 files:

terminal
├── HelloWorld
|   ├── index.js
|   ├── package.json

Configure index.js, adding a shebang at the top to configure the file as a script:

javascript
#!/usr/bin/env node

console.log('Hello world! 🦄🦄🦄');

Now configure package.json and set the bin field with the name of the command that you want to execute:

json
{
  "name": "helloworld",
  "version": "0.0.1",
  "description": "🦄 A simple package that prints a useless hello world",
  "main": "index.js",
  "type": "module",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "start": "node index.js"
  },
  "bin": {
    "hello": "index.js"
  },
  "author": "Erik Martín Jordán",
  "license": "MIT"
}

From the HelloWorld folder, link the package to test it:

javascript
npm link

From the CLI, run:

terminal
> hello
Hello world! 🦄🦄🦄

That's it! If you wish, you could publish the package to npm, running npm publish, but be aware that the package name needs to be available.