LAMdecode.rb

#!/usr/bin/env ruby

require 'base64'

  unless 1 == ARGV.size
    puts <<EOD

Usage:
 LAMdecode.rb filename
EOD
  end

  s = ''
  File.open(ARGV[0]) {|f|
    7.times { f.gets } # cut header
    while l = f.gets
      l.chomp!
      s << l
    end
  }
  print Base64.decode64(s)