isbnconv.rb

#!/usr/bin/ruby
# ISBN13のコードをISBN10に変換して読書メーターのページを開くスクリプト

def isbn13_to_isbn10(s)
  i = 10
  sum = 0
  s[3..-2].split(//).each do |c|
    sum += c.to_i * i
    i -= 1
  end
  if sum % 11 == 0 then
    s[3..-2] + "0"
  elsif sum % 11 == 1 then
    s[3..-2] + "X"
  else
    s[3..-2] + (11 - (sum % 11)).to_s
  end
end

while line = STDIN.gets
  system "open http://book.akahoshitakuya.com/b/" + isbn13_to_isbn10(line.chomp)
end