title: SAS, keeping only columns that contain a certain character
body: <p>I would like to know is it possible to perform an action that keeps only columns that contain a certain character.</p>
  
  <p>For example, lets say that I have columns: name, surname, sex, age.
  I want to keep only columns that start with letter 's' (surname and sex).
  How do I do that?</p>