title: how to conditionally filter rows in awk
body: <p>I am new to awk in linux. I have a large text file with 17 Million rows. The first column is subject <code>ID</code> and the second column is <code>Age</code>. Each subject may have multiple ages and I just want to filter the minimum age for each subject and print them in a separate text file. I am not sure if the subjects are ranked in first column from  low to high... these are the first few rows:</p>
  
  <pre class="lang-none prettyprint-override"><code>ID          Age
  16214497  36.000
  16214497  63.000
  16214727  63.000
  16214781  71.000
  16214781  79.000
  16214792  67.000
  16214860  79.000
  16214862  62.000
  16214874  61.000
  </code></pre>