title: use regex or in cat
body: <p>I have some log files that end in times</p>
  
  <pre><code>1200.gz
  1215.gz
  1230.gz
  1245.gz
  1300.gz
  </code></pre>
  
  <p>When I want to search through all the 12 o'clock files, I do <code>zcat 12**.gz | grep whatever</code> but it usually takes too long. Is there a way to use a regex "or" <code>zcat 12(00|15)</code>? <a href="http://www.ibm.com/developerworks/linux/library/l-lpic1-v3-103-7/" rel="nofollow">This tutorial</a> makes it seem like I can just use square braces, but I get a <code>command not found</code> error.</p>