title: grepping an integer from line start bash
body: <p>I have some homework on "<em>.txt</em>" handling.
  I'm trying to grep lines by exact integer at their start:</p>
  
  <pre><code>grep -hw ^$grep_id ....
  </code></pre>
  
  <p>while grep_id is the exact integer I need.</p>
  
  <p>But it gives me wrong result for example, if I have file".txt" like this:</p>
  
  <pre><code>2
  21
  30
  </code></pre>
  
  <p>If grepping by 2, I get:</p>
  
  <pre><code>2
  21
  </code></pre>
  
  <p>Is there any way to do it?</p>