title: How to use sed to replace regex capture group?
body: <p>I have a large file with many scattered file paths that look like</p>
  
  <pre><code>lolsed_bulsh.png
  </code></pre>
  
  <p>I want to prepend these file names with an extended path like:</p>
  
  <pre><code>/full/path/lolsed_bullsh.png
  </code></pre>
  
  <p>I'm having a hard time matching and capturing these. currently i'm trying variations of: </p>
  
  <pre><code>cat myfile.txt| sed s/\(.+\)\.png/\/full\/path\/\1/g | ack /full/path
  </code></pre>
  
  <p>I think sed has some regex or capture group behavior I'm not understanding</p>