Promise and exec

promisify-child-exec.js

'use strict';
// Idea mainly borrowed from https://stackoverflow.com/a/30883005
const Promise = require('bluebird'); // Not required if you prefer using native promise
const exec = require('child_process').exec;

function promiseExec(command) {
  var child = exec(command);
  return new Promise(function (resolve, reject) {
    child.addListener("error", reject);
    child.stderr.on('data', function (data) {
      reject(data);
    });
    child.stdout.on('data', function (data) {
      resolve(data);
    });
  });
}

promiseExec('wc -l my_file.sql').then(function (results) {
  console.log(results.replace(/[\n\n]/g, '').split(' ')[0]);
}, function (err) {
  console.log('Promise rejected: ' + err);
});