Create a checksum file in each directory

checksum.sh

#!/usr/bin/env bash

readonly FOLDER=$1

create_checksum_file ()
{
  local folder=$1
  local file="$folder/md5_sums"

  echo "Create checksum file $file"
  find "$folder" \
    -maxdepth 1 \
    -type f \
    -exec md5sum {} ';' \
    > "$file"
  find "$folder" \
    -maxdepth 1 \
    -type d \
    -exec echo {} ';' \
    >> "$file"
  sort "$file" -o "$file"
}

main ()
{
  local folder=$1

  create_checksum_file $folder
  find $folder \
    -type d | while read file; do create_checksum_file "$file"; done
}

main $FOLDER