Print variable value inside an html string in Velocity
<p>I need to append a suffix to an URL in Velocity (inside a Liferay template).</p>

<p>I have the following (simplified) code:</p>

<pre><code>#set($isMobile = "")
&lt;img src="http://www.example.com/icon-facebook$isMobile.png" &gt;

#set($isMobile = "-mobile")
&lt;img src="http://www.example.com/icon-facebook$isMobile.png" &gt;
</code></pre>

<p>In my intention this should result in:</p>

<pre><code>&lt;img src="http://www.example.com/icon-facebook.png" &gt;
&lt;img src="http://www.example.com/icon-facebook-mobile.png" &gt;
</code></pre>

<p>but instead I'm obtaining this (as variable is printed literally and not parsed)</p>

<pre><code>&lt;img src="http://www.example.com/icon-facebook$isMobile.png" &gt;
</code></pre>

<p>Please, how to solve?</p>