var fs = require('fs');

fs.mkdir('./hello',0777,function(err){
  if (err) throw err;

  fs.writeFile('./hello/world.txt', 'Hello!', function(err){
    if (err) throw err;
    console.log('File created with contents: ');

    fs.readFile('./hello/world.txt', 'UTF-8', function(err, data){
      if (err) throw err;
      console.log(data);
    });
  });
});