<h1 style='font-size:26px;color:#6aa84f;'>node.js: create a console command without shell scriptig on ubuntu</h1>

Shellscripting for some simple commands are the 90ies. Today we want to setup a console command without any shell scripting. Only with javascript

Prerequisits

At first, you need to have some tools installed. Here they are.
node.js installed
npm installed

$ apt-get install nodejs
$ apt-get install npm

Init your node project

To initialise your project simple type:

$ npm init

This will create your package.json

Fill your projectdata 
My package.json looks like that

{
  "name": "simplecommand",
  "version": "1.0.0",
  "description": "a simple console command",
  "main": "createUser.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/pboethig/nodejs-lessons.git"
  },
  "keywords": [
    "nodejs",
    "command"
  ],
  "author": "pboethig",
  "license": "MIT",
  "bugs": {
    "url": "https://github.com/pboethig/nodejs-lessons/issues"
  },
  "homepage": "https://github.com/pboethig/nodejs-lessons#readme"
}

Add you command script

Get you node.js path

which node

This could output:
/usr/bin/node

Create a file "createUser.js" and add the shebang to it

!#/usr/bin/env node 

This will tell the system to use node.js to execute your script

Make your script executable

chmod a+x createUser.js

Tell npm to install your command
Edit your package.json and add the bin object

{
  "name": "simplecommand",
  "version": "1.0.0",
  "description": "a simple console command",
  "main": "createUser.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "repository": {
    "type": "git",
    "url": "git+https://github.com/pboethig/nodejs-lessons.git"
  },
  "keywords": [
    "nodejs",
    "command"
  ],
  "author": "pboethig",
  "license": "MIT",
  "bugs": {
    "url": "https://github.com/pboethig/nodejs-lessons/issues"
  },

 "bin": {
      "createUser": "createUser.js"
    },
"homepage": "https://github.com/pboethig/nodejs-lessons#readme"

Everytime you modifiý your command, you have to run the global installer

npm install -g

Install commander

To get your command running, we need the commander library, wich does the whole parsing thing for us,

npm install --save commander

Add you command code to the scriptfile

Open your createUser.js and add a simple command

#!/usr/bin/env node

var program = require('commander');

program
    .version('0.0.1')
    .usage('<username>')
    .parse(process.argv);

if(!program.args.length) {
    program.help();
} else {
    console.log('Username: ' + program.args);   
}

As you can see, we are requiring  the commander lib, add an option "username" and parse the input on the terminal.

If no argument was set, we display the helpfile.

If the username was given, we are outputting the username. And we succeed

Instead of that simple sample, you can implement your complex logic here.

That's it. Now you can run your command after you have installed your final scriptversion

$ npm install -g createUser.js 

$ createUser

This will output the helpfile of your new command. Nice !