To check existing users in Ubuntu : cut -d: -f1 /etc/passwd To Add User in Ubuntu : sudo adduser new_username or: sudo useradd new_username To remove/delete a user, first you can use: sudo userdel username To delete the home directory for the deleted user account : sudo rm -r /home/ username (Please use with caution the above command!) To modify the username of a user: usermod -l new_username old_username To change the password for a user: sudo passwd username