title: Edit column value if numeric using Awk
body: <p>What I would like to do is search for lines where the first column does not begin with 'rs' or 'chr' THEN if those lines begin with a number, add 'chr' to the start of the first column value, otherwise leave as it was.</p>
  
  <p>I have the following code:</p>
  
  <pre><code>awk '((!($1 ~ /rs/ || $1 ~ /chr/)) &amp;&amp; $1 ~ /^[[:0-9:]]|$/) {$1 = "chr"$1}1' filename &gt; newfilename
  </code></pre>
  
  <p>This is good but attaches 'chr' to all first column values that do not begin with 'rs' or 'chr'. There are some values in this column that I do not want to change and these all begin with letters (a-z). I only want to change the values which start with numbers (0-9).</p>
  
  <p>Thanks!</p>