fixed Helper function: Get an available uid

helpers/user.js

@@ -36,7 +36,7 @@ exports.getLinuxUsers = (callback) => {
 
 // exports.getLinuxId = (users, callback) => {
 exports.getLinuxId = (callback) => {
-  const path = 'cut -d: -f4 /etc/passwd';
+  const path = 'cut -d: -f3 /etc/passwd';
 
   exec(path, (err, stdout, stderr) => {
     if(err) {