$re = '/(<STYLE>).*(<\/STYLE>)/s';
$str = ' <STYLE>
group 1
</STYLE>
Random text here which shall not be removed.
<STYLE>
group 2
</STYLE>
Some more random text here which shall not be removed.
<STYLE>
group 3
</STYLE>';
preg_match_all($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