title: perl regex - catching four numbers separated by space
body: <p>I know that we can use regex in perl to catch numbers using <code>[\d]</code>, but my pattern is like this:</p>
  
  <pre><code>261 193 546 302
  </code></pre>
  
  <p>or it could be like this:</p>
  
  <pre><code>16 0 98 120
  </code></pre>
  
  <p>The point is - I just want to catch a line that has any four numbers separated by a space. Each number can be made up of any number of digits, it could be a single-digit number, or a double-digit number, and so on.</p>