Usage of HashDeep (apt install hashdeep)

check-checksums.sh

#!/bin/bash

# Files changed or deleted since checksum creation are noted.
# New files are not noted.

if [ -z "$1" ]; then
	DIR=`pwd`
else
	DIR=`realpath $1`
fi
cd $DIR

FILE=checksums.sha1
if [ -f $FILE ]; then
	echo "Checking files in directory" $DIR "against checksums in file" $FILE
	sha1sum --check --quiet --strict $FILE
	if [ $? -eq 0 ]; then echo "OK"; fi
else
	echo "Creating checksums file"
	# find . -type f ! -name "*.sha1" -print0|xargs -0 sha1sum >$FILE
	find . -type f ! -name "*.sha1" -exec sha1sum "{}" \; >>$FILE
	echo $FILE "has been created in" $DIR
fi

hash-audit.sh

#!/bin/bash

# This is a generic script which can be copied into any level of any
# directory tree which should be manually audited for file changes.

DIR=$(dirname `realpath $0`)
FILE=".checksums"
echo Scanning $DIR
cd $DIR
if [ -f $FILE ]; then
	hashdeep -l -r -o f -k $FILE -a -vv *
else
	hashdeep -l -r -o f * >$FILE
	echo $FILE "has been generated in" $DIR
fi