title: Removing non-displaying characters from a file
body: <pre><code>$ cat weirdo 
  Lunch now?
  $ cat weirdo | grep Lunch
  $ vi weirdo
    ^@L^@u^@n^@c^@h^@ ^@n^@o^@w^@?^@
  </code></pre>
  
  <p>I have some files that contain text with some non-printing characters like <code>^@</code> which cause my <code>grep</code>s to fail (as above).</p>
  
  <p>How can I get my <code>grep</code> work? Is there some way that does not require altering the files?</p>