find ext4 partition offset

gistfile1.txt

bs=512

for i in {1..10000000}; do
    echo ">>>>$i"
    mount -o offset=$(($bs*$i)) -t ext4 /dev/sda1 /mnt
    if [ $? == 0 ]; then
        echo "Found ext4 at $(($bs*$i)) bytes !"
        umount /mnt
        break
    fi
done