digest a file with Ruby via OpenSSL

digest.rb

require 'openssl'

def digest_file(file_path, digest_class)
  chunk_size = 1024 * 1024 # a meg
  d = digest_class.new
  File.open(file_path, 'r') do | f |
    while chunk = f.read(chunk_size) do
      d << chunk
    end
  end
  d.hexdigest
end


puts digest_file('/Volumes/FASZT/GiganticFie.huge', OpenSSL::Digest::SHA256)