title: how can i filter whole line which contains a specific string
body: <p>i have the following Ant script for reading revisionlog.txt file line by line and printing all the line.</p>
  
  <pre><code>&lt;target name="line_by_line"&gt;
     &lt;loadfile property="file" srcfile="revisionlog.txt"/&gt;
     &lt;for param="line" list="${file}" delimiter="${line.separator}"&gt;
        &lt;sequential&gt;
           &lt;echo&gt;@{line}&lt;/echo&gt;       
       &lt;/sequential&gt;
     &lt;/for&gt;
  &lt;/target&gt;
  </code></pre>
  
  <p>but here i want to print those line only which contains <code>Comments:</code> string.
  how can i do this.</p>