#!/bin/bash

function helpexit() {
    echo Add more files in md5sum list
    echo 'Usage: m5sum-update [list name]'
    echo 'list name is md5sums.txt by default'
    exit
}

[[ "$1" = "-h" ]] && helpexit
list_name="$1"
[[ -z "$1" ]] && list_name="md5sums.txt"

test -f "$list_name" || touch "$list_name"

for file in *; do
  if [ $file = $list_name ]; then
    continue
  fi
  if test -d "$file"; then
    echo $file is a directory
    continue
  fi
  if test -f "$file"; then
    if grep -q "  $file$" $list_name; then
      echo "$file already added"
    else
      echo "$file adding..." 
      md5sum "$file" >> "$list_name"
    fi
  fi
done

sort -k 2 -o "$list_name" "$list_name"