Creating a TypeScript CLI for Your Monorepo

#typescript #javascript #webdev #programming

I like to create local CLIs for my Monorepo to automate tasks like build and deploy. These tasks often require more than just chaining a few commands in an npm script (like rimraf dist && tsc).

Using commander.js and tsx, we can create executable programs written in TypeScript that run from the command line like any other CLI tool.

#!/usr/bin/env -S pnpm tsx
import { Command } from 'commander';

const program = new Command()
  .name('monorepo')
  .description('CLI for Monorepo')
  .version('1.0.0');

program
  .command('build')
  .description('Build the monorepo')
  .action(async () => {
    console.log('Building...');
    // run your build steps ...
  });

program
  .command('deploy')
  .description('Deploy the monorepo')
  .action(async () => {
    console.log('Deploying...');
    // run your deploy steps ...
  });

await program.parseAsync(process.argv);

Save this script as cli (or any name you prefer) in your project root and make it executable with chmod +x cli. You can then run it directly using ./cli:

$ ./cli
Usage: monorepo [options] [command]

CLI for Monorepo

Options:
  -V, --version   output the version number
  -h, --help      display help for command

Commands:
  build           Build the monorepo
  deploy          Deploy the monorepo
  help [command]  display help for command

The magic that allows you to run this without node, npx, or even a .ts extension is in the first line - the shebang:

#!/usr/bin/env -S pnpm tsx

This shebang tells your shell which program should execute this file. Behind the scenes, it translates your ./cli command into pnpm tsx cli. This works with other package managers too - you can use npm or yarn instead of pnpm.