title: prepend newline to all phrases that match a pattern
body: <p>Suppose my text file looks like this <code>foobar foo bar foobar barfoo</code>.
  I need to add a new line to the front of <code>bar</code> (notice the space before AND after 'bar')</p>
  
  <p>In other words, after running the <code>sed</code> command, I expect to see this</p>
  
  <pre><code>foobar foo
  bar foobar barfoo
  </code></pre>
  
  <p>I've tried the following, but none of them worked!
  sed  -r 's/bar/\nbar/;'
  sed  -r 's/( bar )/\nbar/;'</p>