title: brew link php71: Could not symlink sbin/php-fpm
body: <p>I'm trying to install Laravel Valet, which requires php 7.1, but when i run brew install php71, I get the following error:</p>
  
  <pre><code>==&gt; Pouring php71-7.1.10_21.high_sierra.bottle.tar.gz
  Error: The `brew link` step did not complete successfully
  The formula built, but is not symlinked into /usr/local
  Could not symlink sbin/php-fpm
  /usr/local/sbin is not writable.
  </code></pre>
  
  <p>I get the same error when i run <code>brew link php71</code>. If i run <code>php -v</code>, I actually see that I'm currently running PHP 7.1.7.</p>
  
  <p>But when I run valet install, I get:</p>
  
  <pre><code>  [DomainException]
    Unable to determine linked PHP.
  </code></pre>
  
  <p>I don't even have an sbin directory in /usr/local. </p>
  
  <p>Any suggestions?</p>