compare_md5

#! /usr/bin/env bash

function print_usage() {
echo
echo "$0 <file_to_validate> [<file_with_hash_of_file>] [-p]"
echo "If no hash file is passed, the script will assume it is <filename>.md5"
echo "The -p flag will print out whether the file hash matches the hash provided"
echo "Exits 0 if the computed hash matches the provided hash and 1 otherwise"
echo
}

function nofile() {
echo File ${1} does not exist
exit -1
}

file_to_validate=${1}
if [[ "${2}" = "-p" ]]; then
printout=1
hash_file=${1}.md5
else
hash_file=${2:-${1}.md5}
if [[ "${3}" = "-p" ]];then
printout=1
fi
fi

if [[ -z "$file_to_validate" ]]; then 
print_usage
exit -1
fi

if [[ ! -f "$file_to_validate" ]]; then
nofile "$file_to_validate"
fi
if [[ ! -f "$hash_file" ]]; then
nofile "$hash_file"
fi

computed_hash=$(md5 "${file_to_validate}" | cut -d" " -f4)
received_hash=$(cat "$hash_file" | tail -1 | cut -d" " -f1)

if [[ "$computed_hash" = "$received_hash" ]]; then
failure=0
else
failure=1
fi

if [[ ${printout} = 1  ]]; then
if [[  "${failure}" = 0 ]]; then
echo The file hash is correct
else
echo The file hash does not match the hash provided
fi
fi

exit ${failure}