#!/bin/bash

# userAudit

#Read the passwd file for all the username
file=$(awk -F ":" '{print $1}' /etc/passwd)

for username in $file; do
    firstChar="${username:0:1}"
    badChar=false

#check if the username contain only letters
    for ((i=0; i<${#username}; i++)); do
        char="${username:i:1}"
        if ! [[ "$char" =~ [A-Za-z] ]]; then
            badChar=true
            break
        fi
    done

#if the username is not valid
# longer than 20 characters, start with not a letter and contain other char than letter
# print it
    if  ((${#username} >= 20)) || ! [[ "$firstChar" =~ [A-Za-z] ]] || $badChar ; then
        echo $username
    fi
done