From: "Florian Aßmann" <florian.assmann@...>
Date: 2007-08-24T21:53:58+09:00
Subject: Re: How to append some data at the beginning of a file

My solution for this question would be monkey patching the File class:

require 'tempfile'

class File
  def self.prepend(path, string)
    Tempfile.open File.basename(path) do |tempfile|
      # shift string to tempfile
      tempfile << string

      File.open(path, 'r+') do |file|
        # append original data to tempfile
        tempfile << file.read
        # reset file positions
        file.pos = tempfile.pos = 0
        # copy tempfile back to original file
        file << tempfile.read
      end
    end
  end
end

Regards
Florian