cumentation speaks about something being &quot;wrapped in the ouptut type&quot;, it means the <code>Subprocess_error</code> is raised in the event of non-zero exit status, and otherwise the value is unchanged.</p><div class="odoc-spec"><div class="spec value anchored" id="val-exec"><a href="#val-exec" class="anchor"></a><code><span><span class="keyword">val</span> exec : 
  <span><span><span>(<span class="type-var">'stdin</span>, <span class="type-var">'stdout</span>, <span class="type-var">'stderr</span>)<