Run the command "sudo cat /etc/passwd" and pipe the output to the command "awk -F: 'BEGIN { srand() } { print $1 "[" rand() "]" }'", which will print the usernames from the /etc/passwd file followed by a random number in brackets.
sudo cat /etc/passwd | awk -F: 'BEGIN { srand() } { print $1 "[" rand() "]" }'