title: How best (idiomatically) to fail perl script (run with -n/-p) when input file not found?
body: <pre><code>$ perl -pe 1 foo &amp;&amp; echo ok
  Can't open foo: No such file or directory.
  ok
  </code></pre>
  
  <p>I'd really like the perl script to fail when the file does not exist.  What's the "proper" way to make -p or -n fail when the input file does not exist?</p>