ment goes without any expression. The operator() is overloaded, to obtain the path of the system shell.</p>
<pre class="programlisting"><span class="keyword">auto</span> <span class="identifier">shell_cmd</span> <span class="special">=</span> <span class="identifier">shell</span><span class="special">(</span><span class="special">)</span><span class="special">;</span>
<span class="comment">//avoid exceptions</span>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">er