Tried to reset Admin PW, but Ubuntu isn't recognizing Admin account. How do I fix this?

Question

I recently got a setup with Ubuntu v15.04, but I don't know the admin password. I have some background in IT, and know how to reset it. (BIOS, hold Shift, Adv. Ubuntu -> Memory -> Root, type passwd *root* where root is account name, enter and verify new password.) However, when I enter passwd Aviator (account name), it says 'Aviator' is not a user. I need this computer, how do I get Ubuntu to recognize the account? Thanks. NOTE: The computer does not have WiFi or Ethernet. I CAN access the Guest account and use Terminal, but it has been no help. I'd really rather not have to hack my own computer...

EDIT: Found true username of admin, 'fltsim01'. Entered passwd fltsim01, was asked for New Unix Password, then to Verify, got the following:

passwd: Authentication token manipulation error passwd: password unchanged root@fltsim01-MS-7593:~#

(Note: root@fltsim01-MS-7593:~# is given at Terminal startup, and whenever ready for new command.)

Eyoung, do you want the whole thing? It's 24 two-word lines.

Answer 1

passwd doesn't take the full name of your account; it takes the username (and AFAIK, in Ubuntu, usernames can't start with a capital letter). You can get the corresponding a full name's corresponding username with this command:

grep ':PUT FULL NAME HERE' /etc/passwd | cut -d: -f1

(replacing PUT FULL NAME HERE with the full name you want to search for)

Alternatively, if you don't know the full name you want, you can get a list of usernames and their corresponding full names, seperated by a :, with this command:

cut -d: -f1,5 /etc/passwd | cut -d, -f1

In this case, your username is probably aviator (with a lowercase 'a').

P.S. Ubuntu 15.04 is EOL. It shouldn't affect passwd, but you should upgrade to the latest version (currently 16.04), or at least go to 14.04 or 12.04 if you can.