title: How to see available options for homebrew formula install?
body: <p>I'm reading this stack overflow answer</p>
  
  <p><a href="https://stackoverflow.com/questions/6802410/warning-nokogiri-was-built-against-libxml-version-2-7-8-but-has-dynamically-lo/14658949#answer-10912948">Mac user and getting WARNING: Nokogiri was built against LibXML version 2.7.8, but has dynamically loaded 2.7.3</a></p>
  
  <p>and I just want to know where they learned about the <code>--with-xml2-config</code> option in</p>
  
  <pre><code>brew install libxml2 --with-xml2-config
  </code></pre>
  
  <p>so that I can verify I really want to use this option myself and so I can better solve problems with homebrew myself in the future.</p>
  
  <p>How can I see a description of this specific option and, more generally, find out all the available options for a formula when using brew install?</p>
  
  <p>I know <code>brew info FORMULA</code> gets me some stuff like that, but <code>brew info libxml2</code> only lists the options <code>--universal</code>, <code>--without-python</code>, and <code>--HEAD</code>.</p>
  
  <p>For more info, here is another stack overflow question that is similar to this one but different: <a href="https://stackoverflow.com/questions/15860297/how-can-i-get-more-info-about-a-brew-formula-before-installing">How can i get more info about a brew formula before installing?</a></p>