$re = '/(\d{1,2}) ((д\.)|(дней)|(день))( назад)?/';
$str = '6 д.
23 д.
12 дней
61 день
15 дней назад
62 дней назад
5 ч
6 нед.
три минуты назад
час назад
два часа назад';
preg_match_all($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