script for editing pdf metadata using pdftk

pdfdata.rb

#!/usr/bin/env ruby

require 'tempfile'
require 'fileutils'

FileUtils.mkdir_p "processed"

def metadata(filename)
  command = "pdftk #{filename.dump} dump_data"
  puts command
  f = IO.popen(command)
  str = f.read
  pdfprops(str)
end

def update(filename)
  hash = metadata(filename)
  yield hash if block_given?
  dfile = "#{filename}.data"
  tmp = File.new(dfile, "w")
    hash.each do |k,v|
      tmp.puts "InfoKey: #{k}\nInfoValue: #{v}"
    end
    tmp.flush
    newfile = "processed/" + hash["Title"] 
    command = "pdftk #{filename.dump} update_info #{dfile.dump} output #{newfile.dump}.pdf"
    system command
  tmp.close
end

def pdfprops(data)
  recs = data.scan(/InfoKey:\s(.+)\nInfoValue:\s(.+)/)
  Hash[*recs.flatten]
end

if $PROGRAM_NAME == __FILE__
  author = ARGV.shift
  ARGV.each do |file|
    update(file) do |meta|
      title = File.basename(file, ".pdf")
      meta["Title"] = title
      meta["Author"] = author
    end
  end

end