title: Finding a string pattern using grep
body: <p>I'm trying to find a certain sequence in the text of several .txt files. I am looking for a string that is joined to a 4 digit number. e.g. Watson1990. I tested the regex using an online tester and it appeared to work, however the expression (or combinations of it) failed to produce an output on my files.</p>
  
  <p>My regular expression is as follows:</p>
  
  <pre><code>egrep '\w*\d{4}' *.txt
  </code></pre>
  
  <p>However it does not produce any output. Can you tell me what is wrong with this? I'm using OSX (Snow Leopard).</p>
  
  <p>Thanks.</p>