title: Installing PHP extensions not showing in environment
body: <p>I wasn't sure whether to include this in Ask Ubuntu or Stack Overflow where I decided on Stack Overflow since I'm having some parsing issues.</p>
  
  <p><strong>Using Ubuntu 17.04, PHP5.6 in XAMPP</strong></p>
  
  <p>So I'm trying to use the <strong>bitwasp/bitcoin</strong> composer package and it requires two extensions to be installed, <code>ext-gmp</code> and <code>ext-bcmath</code>, where I have installed them using:</p>
  
  <pre><code>sudo apt-get install php5.6-bcmath
  sudo apt-get install php5.6-gmp
  </code></pre>
  
  <p>When executing the Bitcoin code, I get this error:</p>
  
  <blockquote>
    <p><strong>Fatal error:</strong> Call to undefined function Mdanter\Ecc\Curves\gmp_init() in <strong>/usr/dev/proj/PROECTNAME/vendor/mdanter/ecc/src/Curves/SecgCurve.php</strong> on line <strong>117</strong></p>
  </blockquote>
  
  <p>Bcmath has successfully been found, but gmp hasn't. (using <code>/opt/lampp/bin/php -m</code> it's not on the list)</p>
  
  <p>By running <code>sudo apt-get install php5.6-gmp</code> I get:</p>
  
  <p><a href="https://i.stack.imgur.com/0zyg7.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0zyg7.png" alt="image of terminal text"></a></p>
  
  <p>Here is a <a href="https://pastebin.com/1ideSzzw" rel="nofollow noreferrer">pastebin</a> of the PHP modules I have concerning <code>/opt/lampp/php -m</code>.</p>
  
  <p>Things I've tried:</p>
  
  <ul>
  <li>Purge packages then re-install using different versions, but the default <code>php-gmp</code> package is for PHP7</li>
  <li>Adding <code>extension=gmp</code>, <code>=php_gmp.so</code>, <code>=gmp.so</code>, gives me an error that the extension was not able to be found.</li>
  </ul>