title: grep/ack -o with characters of context (not lines)
body: <p>I'm trying to find a way to</p>
  
  <p><code>grep -o "somepattern"</code></p>
  
  <p>which gives me something like</p>
  
  <pre><code>html/file.js
  2:somepattern
  5:somepattern
  </code></pre>
  
  <p>but what would be really nice is to have a few characters (maybe 20) before and/or after that match.</p>
  
  <p>I know there is a way to show lines before and after (context), but is there any way to show  context by characters? e.g.</p>
  
  <pre><code>html/file.js
  2:function helloWorld(somepattern) {
  5:    var foo = somepattern;
  </code></pre>
  
  <p>The reason I ask is that if I grep recursively and hit a minified file with a match, it prints the entire file, which is super annoying.</p>