# bash4 - Use Associative Arrays to find duplicate files.
# Generate a file "rmdups" which contains rm commands to remove the duplicates.
# Check this file and then source it from the current (!) directory
# to actually remove the duplicates. Works equally with the (deprecated)
# md5sum program instead of sha*sum.
unset flist; declare -A flist
while read -r sum fname; do
    if [[ ${flist[$sum]} ]]; then
        printf 'rm -- "%s" # Same as >%s<\n' "$fname" "${flist[$sum]}" 
    else
        flist[$sum]="$fname"
    fi
done <  <(find . -type f -exec sha256sum {} +)  >rmdups