title: Cut string of numbers at letter in bash
body: <p>I have a string such as <code>plantford1775.274.284b63.11</code>.</p>
  <p>I have been using <code>identity=$( echo &quot;$identity&quot; | cut -d'.' -f3)</code> to cut at each dot, and then choose the third section. I am left with <code>284b63</code>.</p>
  <p>The format of this part is always a letter, sandwiched by varying amounts of numbers. I would like to take the first few numbers before the letter. An example code line would be this:</p>
  <pre><code>identity=$( echo &quot;$identity&quot; | cut -d'anyletter' -f1)
  </code></pre>
  <p>What do I replace <code>anyletter</code> with to cut at whatever letter is listed there, so that I end with a string of <code>284</code>?</p>