title: regex - to check if input is number in csh(unix)
body: <p>Please help. How to make regex work in an if condition, 
  to check user input(in 2nd parameter) must be not equal to any number? </p>
  
  <pre><code>set regex="^[0-9]+$"
  if ($#argv == 2 &amp;&amp; $2 != $regex) then
  # do this
  </code></pre>