title: Is it possible that `fileno(stdout) != 1` on a POSIX system?
body: <p>Can <code>stdout</code> file descriptor differ from <code>1</code> (<a href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/stdin.html" rel="noreferrer"><code>STDOUT_FILENO</code></a>) assuming <a href="https://stackoverflow.com/a/586416/4279"><code>stdout</code> need not be a modifiable lvalue</a>?</p>
  
  <p>For example, can <a href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/freopen.html" rel="noreferrer"><code>freopen("/dev/null", "w", stdout)</code></a> change <code>fileno(stdout)</code> result?</p>