Bun.js as CLI Tool

🛠️ Bun.js as CLI Tool — Supercharge Your Scripts!

Bun.js isn't just a blazing fast JavaScript runtime — it's also an excellent tool for creating and running your own command-line interfaces (CLI).

Whether you're automating workflows, generating boilerplates, or building productivity tools, Bun makes CLI development effortless, efficient, and fun! 🚀

âš¡ Why use Bun.js for CLI Development?

Traditionally, CLI tools were built with Node.js and packaged with tools like pkg or nexe.

But with Bun.js, you get:

• Native speed thanks to Bun’s Zig-powered runtime
• Instant execution of JavaScript and TypeScript files
• Built-in utilities like bunx and bun run
• Easy permissions using shebangs for script execution

📁 Setting Up a Bun CLI Project

Start by initializing a new Bun project:

bun init

Then create a new CLI script file, for example: cli.ts

🚀 Creating a Simple CLI Script

Here's a basic CLI script that echoes user input:

// cli.ts
#!/usr/bin/env bun

const name = Bun.argv[2] || "World";
console.log(`👋 Hello, ${name}!`);

Note: Don’t forget the shebang #!/usr/bin/env bun at the top — it tells the system to run the file using Bun!

🔒 Making the Script Executable

To make your file executable on Unix-based systems (Linux/macOS):

chmod +x cli.ts

Now you can run your CLI like this:

./cli.ts BunUser

📦 Distributing Your CLI Tool

Want to share your CLI with the world? Use bunx for a zero-install experience:

bunx githubuser/repo

Or create a custom command in your package.json:

// package.json
{
  "scripts": {
    "greet": "./cli.ts"
  }
}

Then simply run:

bun run greet BunUser

📚 Handling Arguments with Deno-style Simplicity

Bun provides access to command-line arguments via Bun.argv.

You can easily parse flags or values:

// cli.ts
#!/usr/bin/env bun

const args = Bun.argv.slice(2);

if (args.includes("--help")) {
  console.log(`Usage: ./cli.ts [name]`);
} else {
  const name = args[0] || "Bun";
  console.log(`👋 Hello, ${name}!`);
}

🔧 Add Styling & UX to your CLI

Use colors, emojis, and prompts to enhance CLI UX.

You can install and use packages like chalk (with ESM support):

bun add chalk

// cli.ts
#!/usr/bin/env bun
import chalk from "chalk";

console.log(chalk.green("✔️ Success! Your CLI is working."));

💡 Pro Tip: Use Bun with Templates

Want to scaffold projects with your CLI? Use fs module to copy files or write templates:

// cli.ts
#!/usr/bin/env bun
import { writeFileSync } from "fs";

writeFileSync("hello.txt", "Generated by Bun CLI! 💥");
console.log("📄 File created: hello.txt");

✅ Conclusion

Bun.js makes building CLI tools a breeze — fast, modern, and with zero setup.

Whether you're building developer utilities or productivity hacks, Bun has all the power you need packed in a lightweight runtime. 🌟

Ready to script your way to greatness? Try Bun.js as a CLI tool today! 💻✨

---