const { spawn } = require('child_process');

const subprocess = spawn(process.argv[0], ['child_program.js'], {
  detached: true,
  stdio: 'ignore'
});

subprocess.unref();

const { spawn } = require('child_process');

const subprocess = spawn(process.argv[0], ['child_program.js'], {
  detached: true,
  stdio: 'ignore'
});

subprocess.unref();
subprocess.ref();

const fs = require('fs');
const { spawn } = require('child_process');
const out = fs.openSync('./out.log', 'a');
const err = fs.openSync('./out.log', 'a');

const subprocess = spawn('prg', [], {
  detached: true,
  stdio: [ 'ignore', out, err ]
});

subprocess.unref();

const { spawn } = require('child_process');

const subprocess = spawn('ls');

subprocess.stdout.on('data', (data) => {
  console.log(`Received chunk ${data}`);
});

var spawn = require('child-process-promise').spawn;
 
var promise = spawn('echo', ['hello']);
 
var childProcess = promise.childProcess;
 
console.log('[spawn] childProcess.pid: ', childProcess.pid);
childProcess.stdout.on('data', function (data) {
    console.log('[spawn] stdout: ', data.toString());
});
childProcess.stderr.on('data', function (data) {
    console.log('[spawn] stderr: ', data.toString());
});
 
promise.then(function () {
        console.log('[spawn] done!');
    })
    .catch(function (err) {
        console.error('[spawn] ERROR: ', err);
    });