#!/bin/bash

# This script calculates a sha256sum over all files in a dirextory including its subdirectories

# Length of the sha256 hash. Adapt when changing hash algorithm
hashlen=64

if [[ -z $1 ]]; then
	echo "Usage: $0 <path to folder>"
	exit -1
fi

if [[ ! -d "$1" ]]; then
	echo "Specified path: $1 is not a directory"
	exit -2
fi

search_dir="$1"

filelist=()
while IFS= read -d $'\0' -r file ; do
	filelist=("${filelist[@]}" "$file")
done < <(find "$search_dir" -type f -print0 | sort -z)

echo "Found ${#filelist[@]} files"

# Calculate shasums over all files
shasum=`for file in "${filelist[@]}"; do
	sha256sum "$file" | head -c $hashlen
	echo ""
done | sha256sum | sed 's/\s-//'`

echo "$shasum"