#!/bin/bash


while read -n 1 line
do
dec="$dec$(printf '%d' \'"$line")"
done <<< "aaaa"
printf "%s\n" "$dec"

while read -n 2 line
do
ascii="$ascii$(printf '%b' $(printf '\\%03o' "$line"))"
done <<< "97979797"
printf "%s\n" "$ascii"