Hackernoon logoMaking Command-Line Interface (CLI) for Fun and Profit by@CK

Making Command-Line Interface (CLI) for Fun and Profit

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@CKCK

Technical Founder @ TAGGUN

Next time you have an idea ūüí° "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. And, CLI uses command flags and help text to prevent you from making silly 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. By the way, we make APIs for receipt OCR scanning. And I recommend oclif: The Open CLI Framework by Heroku for creating and managing CLIs.

How to create a new CLI

Install node.js first.
Start by scaffolding the CLI
$ 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 folder 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

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