title: Don't print filenames in zgrep output when searching multiple files
body: <p>When I use zgrep to search multiple .gz files, the output contains the filename in it. Sometimes I don't need it bcz I use some other scripts to parse the output. </p>
  
  <p>I tried using "-h" option but it doesn't seem to work with zgrep. </p>
  
  <p>This is how I use the command:</p>
  
  <pre><code>admin@mybox [11:16:56]&gt; zgrep -Eh "\.ERR|\.WARNING|\.FATAL" messages.?.gz
  messages.1.gz:Oct 14 10:02:06 .............................................
  messages.2.gz:Oct 14 09:27:58 .............................................
  </code></pre>
  
  <p>Any idea how I can stop the filename from being printed?</p>