getuser.js

var exec = require('child_process').exec;
function execute(command, callback){
    exec(command, function(error, stdout, stderr){ callback(stdout); });
};

module.exports.getUser = function(callback){
    execute("whoami", function(name){
            callback({ name: name.replace("\n", "") });
    });
};

this.getUser(function(user) {

if (user.name !== 'root') {
    console.log("not root!");
    process.exit(1);
    }
console.log(user.name);
})