title: unix sort for 2 fields numeric order
body: <p>I need to sort some data with unix sort but I can't figure exactly the right syntax, the data looks like</p>
  
  <pre><code>3.9.1 Step 10:
  3.9.1 Step 20:
  3.8.10 Step 20:
  3.10.2 Step 10:
  3.8.4 Step 90:
  3.8.4 Step 100:
  3.8.4 Step 10:
  </code></pre>
  
  <p>I want to sort it using first the major number, then the step number, e.g. the data sorted above would look like.</p>
  
  <pre><code>3.8.4 Step 10:
  3.8.4 Step 90:
  3.8.4 Step 100:
  3.8.10 Step 20:
  3.9.1 Step 10:
  3.9.1 Step 20:
  3.10.2 Step 10:
  </code></pre>
  
  <p>I have found the way to sort by first number on this site:</p>
  
  <pre><code>sort -t. -k 1,1n -k 2,2n -k 3,3n
  </code></pre>
  
  <p>but I am struggling to now sort by the 3rd column Step number without disturbing the first sort</p>