Avoid to rewrite a file that already exists
<p>I write this simple code to save an image:</p>

<pre><code>// $randomimage contains a random image url.
$content = file_get_contents($randomimage);
file_put_contents('images/'.$randomimage, $content);
</code></pre>

<p>I need a way to NOT rewrite an image with the same name. So, if an image with a certain name already exist in my /images/ folder, then do NOTHING.
It's simple but I don't know how to do that.</p>
