$re = '/(\[monitor:[^[]+?)^(ignoreOlderThan\s?=\s?[0-9]+\w)([^[]+?^ignoreOlderThan\s?=\s?[0-9]+\w[^[]+)/ms';
$str = '[default]
host = 10.2.2.15
[monitor://apath]
ignoreOlderThan = 14d
index=test
sourcetype=whatever
ignoreOlderThan = 30d
Testing
[monitor://truck]
ignoreOlderThan = 14d';
preg_match_all($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