$re = '/[\w]{8}\s+(INFO|WARN|ERROR)\s+\d\d:\d\d:\d\d\.\d\d\d/';
$str = 'pdlvkw6v INFO 18:25:03.994 pdlvkw6v WARN 18:25:03.994 pdlvkw6v INFO 18:25:03.994 rg9n9bz7 INFO 18:23:52.987 rg9n9bz7 ERROR 19:23:52.987
rg9n9bz7 INFO 21:23:52.987 5y6n9bz7 WARN 18:23:52.987 ';
preg_match_all($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