title: Reading a text file and writing to another text file in Ruby
body: <p>I want to take a text file, foo.txt that is a list of 10 digit numbers, each on their own line. If a number meets a certain set of parameters, I want that line written to bar.txt.</p>
  
  <p>What is an easy way to do this in straight up Ruby? I'm new to file parsing in Ruby and just need a little help to get started.</p>