title: Why is this "can't break line" warning from grep of gcc man page?
body: <p>I was trying to find a line ending with <code>-s</code> with the following command but got warnings:</p>
  
  <pre><code>$ man gcc | grep '\-s$'
  &lt;standard input&gt;:4808: warning [p 54, 13.2i]: can't break line
  $ man gcc | egrep '\-s$'
  &lt;standard input&gt;:4808: warning [p 54, 13.2i]: can't break line
  </code></pre>
  
  <p>Below is my development environment:</p>
  
  <pre><code>$ uname -a
  Linux localhost 3.16.0-4-amd64 #1 SMP Debian 3.16.7-ckt20-1+deb8u1 (2015-12-14) x86_64 GNU/Linux
  
  $ gcc --version
  gcc (Debian 4.9.2-10) 4.9.2
  Copyright (C) 2014 Free Software Foundation, Inc.
  This is free software; see the source for copying conditions.  There is NO
  warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  </code></pre>