#!/bin/bash
s="bar
quux
kabe
Ass
sBo
CcdD
FGH"
grep -o '\b[^[:upper:]]*[[:upper:]][^[:upper:]]*\b' <<< "$s"
grep -o '\b[[:lower:]]*[[:upper:]][[:lower:]]*\b' <<< "$s"
IyEvYmluL2Jhc2gKcz0iYmFyCnF1dXgKa2FiZQpBc3MKc0JvCkNjZEQKRkdIIgpncmVwIC1vICdcYlteWzp1cHBlcjpdXSpbWzp1cHBlcjpdXVteWzp1cHBlcjpdXSpcYicgPDw8ICIkcyIKZ3JlcCAtbyAnXGJbWzpsb3dlcjpdXSpbWzp1cHBlcjpdXVtbOmxvd2VyOl1dKlxiJyA8PDwgIiRzIg==