title: How to make GREP select only numeric values?
body: <p>I use the <code>df</code> command in a bash script:</p>
  
  <pre><code>df . -B MB | tail -1 | awk {'print $4'} | grep  .[0-9]*
  </code></pre>
  
  <p>This script returns:</p>
  
  <pre><code>99%
  </code></pre>
  
  <p>But I need only numbers (to make the next comparison).
  If I use the <code>grep</code> regex without the dot:</p>
  
  <pre><code>df . -B MB | tail -1 | awk {'print $4'} | grep  .[0-9]*
  </code></pre>
  
  <p>I receive nothing.
  How to fix?</p>