simple wrapper of nodejs native spawn child process for a exec like func

runCmd.js

function runCmd(cmd, args, callback) {
   var spawn = require('child_process').spawn;
   var child = spawn(cmd, args);
   var out = '';
   var err = '';
   child.stdout.on('data', function(buffer) { out += buffer.toString(); });
   child.stderr.on('data', function(buffer) { err += buffer.toString(); });
   child.on('close', function(code) { callback(code, out, err); });
}

runCmd('ls', [ '/usr' ], function(code, stdout, stderr) {
  if (code !== 0) {
    console.error(stderr);
    process.exit(code);
  }
  console.log(stdout);
});