$re = '/[\"\']([\a-zA-Z0-9-_]*logo[a-zA-Z0-9\-_]*\.(?:png|jpg|jpeg)).*?"/mi';
$str = '/example/logo.png
/example/logo_adsadsa.jpg
"/e/logo_adsada.jpg?size=400"
src="dadsadsadadadadsadasdadsadsalogosdsd.png"
<html>
<head>
<style>
someclass {
background-image: url("/css/images/logo2.jpg");"
background-color: #cccccc;
}
</style>
</head>
<body>
<h1>Hello World!</h1>
</body>
<html>';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php