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532 lines
7.7 KiB
Markdown
532 lines
7.7 KiB
Markdown
Build an interactive CLI with Node.js
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======
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Node.js can be very useful when it comes to building command-line interfaces (CLIs). In this post, I'll teach you how to use [Node.js][1] to build a CLI that asks some questions and creates a file based on the answers.
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### Get started
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Let's start by creating a brand new [npm][2] package. (Npm is the JavaScript package manager.)
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```
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mkdir my-script
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cd my-script
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npm init
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```
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Npm will ask some questions. After that, we need to install some packages.
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```
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npm install --save chalk figlet inquirer shelljs
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```
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Here's what these packages do:
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* **Chalk:** Terminal string styling done right
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* **Figlet:** A program for making large letters out of ordinary text
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* **Inquirer:** A collection of common interactive command-line user interfaces
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* **ShellJS:** Portable Unix shell commands for Node.js
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### Make an index.js file
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Now we'll create an `index.js` file with the following content:
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```
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#!/usr/bin/env node
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const inquirer = require("inquirer");
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const chalk = require("chalk");
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const figlet = require("figlet");
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const shell = require("shelljs");
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```
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### Plan the CLI
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It's always good to plan what a CLI needs to do before writing any code. This CLI will do just one thing: **create a file**.
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The CLI will ask two questions—what is the filename and what is the extension?—then create the file, and show a success message with the created file path.
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```
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// index.js
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const run = async () => {
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// show script introduction
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// ask questions
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// create the file
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// show success message
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};
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run();
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```
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The first function is the script introduction. Let's use `chalk` and `figlet` to get the job done.
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```
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const init = () => {
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console.log(
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chalk.green(
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figlet.textSync("Node JS CLI", {
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font: "Ghost",
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horizontalLayout: "default",
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verticalLayout: "default"
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})
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)
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);
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}
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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// create the file
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// show success message
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};
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run();
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```
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Second, we'll write a function that asks the questions.
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```
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const askQuestions = () => {
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const questions = [
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{
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name: "FILENAME",
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type: "input",
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message: "What is the name of the file without extension?"
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},
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{
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type: "list",
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name: "EXTENSION",
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message: "What is the file extension?",
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choices: [".rb", ".js", ".php", ".css"],
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filter: function(val) {
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return val.split(".")[1];
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}
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}
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];
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return inquirer.prompt(questions);
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};
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// ...
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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// show success message
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};
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```
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Notice the constants FILENAME and EXTENSIONS that came from `inquirer`.
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The next step will create the file.
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```
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const createFile = (filename, extension) => {
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const filePath = `${process.cwd()}/${filename}.${extension}`
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shell.touch(filePath);
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return filePath;
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};
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// ...
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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const filePath = createFile(FILENAME, EXTENSION);
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// show success message
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};
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```
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And last but not least, we'll show the success message along with the file path.
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```
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const success = (filepath) => {
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console.log(
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chalk.white.bgGreen.bold(`Done! File created at ${filepath}`)
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);
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};
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// ...
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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const filePath = createFile(FILENAME, EXTENSION);
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// show success message
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success(filePath);
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};
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```
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Let's test the script by running `node index.js`. Here's what we get:
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### The full code
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Here is the final code:
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```
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#!/usr/bin/env node
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const inquirer = require("inquirer");
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const chalk = require("chalk");
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const figlet = require("figlet");
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const shell = require("shelljs");
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const init = () => {
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console.log(
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chalk.green(
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figlet.textSync("Node JS CLI", {
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font: "Ghost",
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horizontalLayout: "default",
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verticalLayout: "default"
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})
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)
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);
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};
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const askQuestions = () => {
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const questions = [
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{
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name: "FILENAME",
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type: "input",
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message: "What is the name of the file without extension?"
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},
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{
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type: "list",
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name: "EXTENSION",
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message: "What is the file extension?",
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choices: [".rb", ".js", ".php", ".css"],
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filter: function(val) {
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return val.split(".")[1];
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}
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}
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];
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return inquirer.prompt(questions);
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};
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const createFile = (filename, extension) => {
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const filePath = `${process.cwd()}/${filename}.${extension}`
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shell.touch(filePath);
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return filePath;
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};
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const success = filepath => {
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console.log(
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chalk.white.bgGreen.bold(`Done! File created at ${filepath}`)
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);
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};
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const run = async () => {
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// show script introduction
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init();
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// ask questions
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const answers = await askQuestions();
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const { FILENAME, EXTENSION } = answers;
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// create the file
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const filePath = createFile(FILENAME, EXTENSION);
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// show success message
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success(filePath);
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};
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run();
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```
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### Use the script anywhere
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To execute this script anywhere, add a `bin` section in your `package.json` file and run `npm link`.
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```
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{
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"name": "creator",
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"version": "1.0.0",
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"description": "",
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"main": "index.js",
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"scripts": {
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"test": "echo \"Error: no test specified\" && exit 1",
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"start": "node index.js"
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},
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"author": "",
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"license": "ISC",
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"dependencies": {
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"chalk": "^2.4.1",
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"figlet": "^1.2.0",
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"inquirer": "^6.0.0",
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"shelljs": "^0.8.2"
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},
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"bin": {
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"creator": "./index.js"
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}
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}
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```
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Running `npm link` makes this script available anywhere.
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That's what happens when you run this command:
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```
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/usr/bin/creator -> /usr/lib/node_modules/creator/index.js
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/usr/lib/node_modules/creator -> /home/hugo/code/creator
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```
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It links the `index.js` file as an executable. This is only possible because of the first line of the CLI script: `#!/usr/bin/env node`.
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Now we can run this script by calling:
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```
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$ creator
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```
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### Wrapping up
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As you can see, Node.js makes it very easy to build nice command-line tools! If you want to go even further, check this other packages:
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* [meow][3] – a simple command-line helper
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* [yargs][4] – a command-line opt-string parser
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* [pkg][5] – package your Node.js project into an executable
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Tell us about your experience building a CLI in the comments.
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--------------------------------------------------------------------------------
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via: https://opensource.com/article/18/7/node-js-interactive-cli
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作者：[Hugo Dias][a]
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选题：[lujun9972](https://github.com/lujun9972)
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译者：[译者ID](https://github.com/译者ID)
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校对：[校对者ID](https://github.com/校对者ID)
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本文由 [LCTT](https://github.com/LCTT/TranslateProject) 原创编译，[Linux中国](https://linux.cn/) 荣誉推出
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[a]:https://opensource.com/users/hugodias
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[1]:https://nodejs.org/en/
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[2]:https://www.npmjs.com/
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[3]:https://github.com/sindresorhus/meow
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[4]:https://github.com/yargs/yargs
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[5]:https://github.com/zeit/pkg
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