Making Command-line interface (CLI) for fun and profit

Next time you have an idea 💡 "I know... Why don't I write a script to automate this thing?" Actually, you should not, you should write a CLI instead.

CLI has better structure than scripts. CLI uses flags and help text to avoid mistakes. For example:

$ moa --help
Moa makes it easier to run your local node.js apps.

USAGE
  $ moa

OPTIONS
  -c, --commands=commands  [default: start] commands to run.
  -h, --help               show CLI help
  -r, --root=root          [default: ../] root path to run.

DESCRIPTION
  ...
  Have some fun

Scripts are messy. And can get out of control.

At Taggun, we run a lot of node.js application. We make APIs for receipt OCR scanning, by the way. So, I recommend oclif: The Open CLI Framework by Heroku.

How to create a new CLI

Install node.js first.

Start by scaffolding

$ npx oclif single moa
? npm package name (moa): moa
$ cd moa

Modify your flags in `src\index.js`

MoaCommand.flags = {
  // add --help flag to show CLI version
  help: flags.help({char: 'h'}),
  commands: flags.string({char: 'c', description: 'commands to run. Comma-separated.', default: 'start'}),
  root: flags.string({char: 'r', description: 'root path to run.', default: '../'}),
}

Modify your description in `src\index.js`

MoaCommand.description = `Moa makes it easier to run your local node.js apps.

Modify your command in `src\index.js`

class MoaCommand extends Command {
  async run() {
    const {flags} = this.parse(MoaCommand)
    const commands = flags.commands.split(',')
    const {root} = flags
    find.file(/(?<!node_modules\/.*)\/package\.json$/, root, files => {
      files.forEach(async file => {
        const cwd = require('path').dirname(file)
        commands.forEach(async command => {
          this.log(cwd, `npm run ${command}`)
          const npm = spawn('npm', ['run', command], {cwd})
          for await (const output of npm.stdout) {
            this.log(`${file}: ${output}`)
          }
        })
      })
    })
  }
}

In this example, you will need to run npm i find to install find npm module.

This simple CLI will look for all node.js application in the [root] and run npm run [command]. Great if you need to run multiple node.js application to start coding.

Run it

./bin/run -c start -c ../taggun/

Publish and share your CLI

See https://oclif.io/docs/releasing

Blog

Making Command-line interface (CLI) for fun and profit

CK Lee

How to create a new CLI

Start by scaffolding

Modify your flags in `src\index.js`

Modify your description in `src\index.js`

Modify your command in `src\index.js`

Run it

Publish and share your CLI

Join Our Newsletter. No Spam, Only the good stuff.

Related

Making Command-line interface (CLI) for fun and profit

CK Lee

How to create a new CLI

Start by scaffolding

Modify your flags in src\index.js

Modify your description in src\index.js

Modify your command in src\index.js

Run it

Publish and share your CLI

Join Our Newsletter. No Spam, Only the good stuff.

Related

Modify your flags in `src\index.js`

Modify your description in `src\index.js`

Modify your command in `src\index.js`