Cannot Launch `gksudo` using NodeJs `exec`

Question

Goal

I want to show graphical password prompt in nodejs to elevate priviledge thus gain some power to copy file content into another, but the last is owned by root.

In the implementation, I try to execute dd along with it's argument with gksudo with exec() function.

exec = require('child_process').exec

printall = function (error, stdout, stderr) {
  console.log('stdout: ' + stdout);
  console.log('stderr: ' + stderr);
  if (error) {
    console.log('exec err: ' + error);
  }
}

exec("gksudo dd if=/home/user/minor.txt of=/home/user/major.txt", printall)

Error

But I always fail, with no good reason.

It said,

stdout: 
stderr: 
exec err: Error: Command failed: /bin/sh -c gksudo dd if=/home/user/minor.txt of=/home/user/major.txt

If I reproduce the command into terminal, it missed double quotes and instead run gksudo only. Well, in nodejs, it simply fails.

Notes

I originally develop Atom package. It's my first time, so, I found out about a different version of Node (or IOJs?). I execute the whole code inside Atom.

Question

If you expect a clear question, well, possibly

How to execute gksudo within node.js to run other command along with the arguments?