$re = '/^(?!(.+-front))(.*?)-(glass|glass-.*?lcd|lcd)-.*?(replacement|repair)(.*?)/m';
$str = 'iphone-repair/iphone-4s-repair/iphone-4s-lcd-repair
iphone-repair/iphone-4s-repair/iphone-4s-glass-repair
iphone-repair/iphone-4s-repair/iphone-4s-glass-amp-lcd-replacement
iphone-repair/iphone-4s-repair/iphone-4s-front-glass-amp-lcd-amp-back-glass-replacement';
preg_match_all($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