Script for searching matching blocks in a drive

search_duplicate.bash

#!/bin/bash

# This script searches for matching blocks in a drive
# VERSION 1

# License: GNU GPL version 3 or any later version as released by the Free Software Foundation
# NO WARRANTY

# Author: reddit.com user gnulicious

# THIS SCRIPT DOES NOT DO SANITY CHECKING ON ITS ARGUMENTS. Be sure you know what you're doing.

[[ $# != 6 ]] && { echo "Expected 6 arguments. See script code." ; exit ; }

# ALL UNITS ARE IN SECTORS (512 Bytes)
file="$1"
size="$2"
origin="$3"
search_start="$4"
search_end="$5"
search_increment="$6"


#Options
end_at_first_match=false

# get the md5sum and sha1sum of the origin chunk
origin_md5=$(dd bs=512 count="$size" if="$file" skip="$origin" | md5sum -b - )
origin_sha1=$(dd bs=512 count="$size" if="$file" skip="$origin" | sha1sum -b - )


declare -a match_locations

search="$search_start"

printf "Starting search..."
while [[ "$search" -lt "$search_end" && ( ${#match_locations[*]} -lt 1 || "$end_at_first_match" != true ) ]] ; do

    [[ "$(dd bs=512 count="$size" if="$file" skip="$search" | md5sum  -b - )" == "$origin_md5"  ]] &&
    [[ "$(dd bs=512 count="$size" if="$file" skip="$search" | sha1sum -b - )" == "$origin_sha1" ]] &&
    { printf "\nMatch found at location: $search\n" ; match_locations+=("$search") ; }

    printf "."
    search=$((search + search_increment))
done


if [[ ${#match_locations[@]} -gt 0 ]]; then
    echo
    echo "With arguments $@, found matches at the following locations:"
    for location in "${match_locations[@]}"; do
        echo "$location" ;
    done
else
    echo "No matches found."
fi