# File lib/rails-installer.rb, line 325
  def copy_one_file(filename)
    source_name = File.join(source_directory,filename)
    install_name = File.join(install_directory,filename)
    dir_name = File.dirname(install_name)
    
    mkdir_p(dir_name)
    cp(source_name,install_name,:preserve => true)
  end