Script for copying files in blocks, performing checksums on each part

copy-check.sh

#!/bin/bash
INFILE=$1
OUTFILE=$2
SIZE="1M" #Linux
#SIZE="1m" #OSX
if [ -z "$2" ]; then
    echo "Usage: $0 INFILE OUTFILE [INIT] [END]"
    exit 1
fi

if [ ! -f "${INFILE}" ]; then
	echo "Error: INFILE not found"
fi

if [ ! -f "${OUTFILE}" ]; then
	cp -v "${INFILE}" "${OUTFILE}"
	RESULT=$(diff -q <(sha256sum "${INFILE}" | awk '{print $1}') <(sha256sum "${OUTFILE}" | awk '{print $1}'))
	if [ -z "${RESULT}" ]; then
		echo "[+] COPY OK"
		exit 0
	else
		echo "[-] CHECKSUM FAIL"
	fi
fi

if [ -z "$3" ]; then
	INIT=0
else
	INIT=$3
fi
if [ -z "$4" ]; then
	END=$(du --block-size=${SIZE} "${INFILE}" | awk '{print $1}') #LINUX
	#END=$(du -m "${INFILE}" | awk '{print $1}') #OSX
	END=$(($END - 1))
else
	END=$4
fi

INFILESIZE=$(du -ms "${INFILE}" | awk '{print $1}')
OUTFILESIZE=$(du -ms "${OUTFILE}" | awk '{print $1}')
if [ "${INFILESIZE}" != "${OUTFILESIZE}" ]; then
	echo "Error: FILES SIZE ${INFILESIZE}!=${OUTFILESIZE}"
	exit 1
fi

echo "== COPY AND CHECK ==="
echo "INFILE: ${INFILE}"
echo "OUTFILE: ${OUTFILE}"
echo "INIT: ${INIT} - END: ${END}"
sleep 2
BADBLOCKS=0
for N in $(seq ${INIT} ${END}); do
	RESULT=$(diff -q <(dd if="${INFILE}" bs=${SIZE} skip=${N} count=1 2>/dev/null | xxd -a) <(dd if="${OUTFILE}" bs=${SIZE} skip=${N} count=1 2>/dev/null | xxd -a))

	if [ -z "${RESULT}" ]; then
		echo -en "\r$N OK"
	else
		BADBLOCKS=$((BADBLOCKS + 1))
		while [ -n "${RESULT}" ]; do
			echo -e "\r$N DIFF"
			dd if="${INFILE}" of="${OUTFILE}" bs=${SIZE} skip=${N} seek=${N} count=1 conv=notrunc status=none
			sleep 0.1
			RESULT=$(diff -q <(dd if="${INFILE}" bs=${SIZE} skip=${N} count=1 2>/dev/null | xxd -a) <(dd if="${OUTFILE}" bs=${SIZE} skip=${N} count=1 2>/dev/null | xxd -a))
		done
		echo -en "\r$N OK"
	fi
done

echo -e "\n[+] Finished"
echo "Total bad blocks: ${BADBLOCKS}"
sha256sum "${INFILE}" "${OUTFILE}"