Enjoy! Let me know if you see anything that needs to be corrected 
for our newer users, sometimes its not common knowledge to guess the username as the creator of the box.
the better way to find out what users are on the system is to test input validation on the input box. ideally the developer would have limited input to only the commands listed on the page. in reality he or she didn’t and we’re able to enter the path to etc passwd and have the passed file presented to us which shows us that charix is a user.