$re = '/^(?!.*\/[0-9A-F]{40}\/).*$/m';
$str = '/dev/api/appid/A1B2C3D4E5A1B2C3D4E5A1B2C3D4E5A1B2C3D4E5/users
/dev/api/apps/list
/dev/api/help/apps/applicationname/apple/osversion/list/';
preg_match_all($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