iated to a variable in the process
    environment or <code class="code"><span class="constructor">None</span></code> if the variable is unbound.</p>
</div>
<ul class="info-attributes">
<li><b>Since</b> 4.05</li>
</ul>
</div>

<pre><span id="VALcommand"><span class="keyword">val</span> command</span> : <code class="type">string -&gt; int</code></pre><div class="info ">
<div class="info-desc">
<p>Execute the given shell command and return its exit code.</p>
</div>
</div>

<pre><span id="VALtime"><span class=