#!/usr/bin/env bash
#
# Common bytes in avi files
# Stop once differences

COUNT=1

function helper(){
    echo "SYNTAX:
$0 fileone filetwo
These did ought to be of the same file type"
    exit
}

if (( $# != 2 )) || [ ! -f $1 ] || [ ! -f $2 ]; then
    helper
fi

while( true ); do
    ONE="$(od --read-bytes=$COUNT $1)"
    TWO="$(od --read-bytes=$COUNT $2)"
    if [ "$ONE" = "$TWO" ]; then
	COUNT=$(($COUNT+1))
    else
	echo "First $COUNT Identical"
	exit
    fi
done