From: eggie5 [mailto:eggie5 / gmail.com] 
> I have list (array) of file names in the form:
> 
> What's the fastest way I can check if these files exist in a given
> directory?

Dir.chdir( source_directory ) do
  my_array.each do |file_name|
    if File.exist?( file_name )
      ...
    else
      ...
    end
  end
end