title: Filter file with awk and keep header in output
body: <p>I have following CSV file:</p>
  
  <pre><code>a,b,c,d
  x,1,1,1
  y,1,1,0
  z,1,0,0
  </code></pre>
  
  <p>I want to keep lines that add up more than 1, so I execute this awk command:</p>
  
  <pre><code>awk -F "," 'NR &gt; 1{s=0; for (i=2;i&lt;=NF;i++) s+=$i; if (s&gt;1)print}' file
  </code></pre>
  
  <p>And obtain this:</p>
  
  <pre><code>x,1,1,1
  y,1,1,0
  </code></pre>
  
  <p>How can I do the same but retain the first line (header)?</p>