Verify hashes non-visually. Too many people only compare the first and/or last few hex digits, which is too easy to collide.

vhash.sh

#!/bin/sh

z=$(basename "$0")

err() {
	printf "%s: %s\n" "$z" "$1" >&2
	exit 1
}

usage() {
	printf "Usage: %s file hash [algo]\n" "$z"
	exit 2
}

[ $# -eq 2 -o $# -eq 3 ] || usage

file=$1
hash=$2

if [ $# -eq 3 ]; then
	algo="$3"
else
	# Guess hash algorithm by length.
	len=$(printf %s "$2" | wc -c | awk '{print $1}')
	case "$len" in
	128) algo=sha512 ;;
	64) algo=sha256 ;;
	40) algo=sha1 ;;
	32) algo=md5 ;;
	*) err "unknown hash type (length $len)" ;;
	esac
fi

actual=$(openssl dgst -r -"$algo" < "$file" | cut -d' ' -f1)

if [ X"$actual" = X"$hash" ]; then
	echo "$algo OK"
	exit 0
else
	echo "$algo FAIL"
	printf "\twanted: %s\n" "$hash"
	printf "\tactual: %s\n" "$actual"
	exit 1
fi