generate offset disk image and mount it

#!/usr/bin/bash
# generates an offset disk image from efi partition
# which is added afterwards to a 512k * 8 size /dev/zero image
# mounts the efi image with the corresponding specific offset

BLOCKSIZE=`echo '512  * 1024' | bc`
SEEK=8
OFFSET=$(echo "$BLOCKSIZE * $SEEK" | bc)

dd if=/dev/zero of=zero.img bs=512k count=8
cp zero.img offset_disk.img
dd if=/dev/nvme0n1p15 of=offset_disk.img bs=$BLOCKSIZE seek=$SEEK oflag=append

du -h -s *.img
mkdir -p /mnt/efi
mount -o loop,offset=$OFFSET offset_disk.img /mnt/efi
df -h  | grep efi

sleep 1
umount /mnt/efi
rm -f zero.img offset_disk.img
exit 0