$re = '/^(?<timestamp>\d+-\d+-\d+T\d+:\d+:\d+\.\d+([+-])\d+:\d+)\s+\[(?<severity>\w+)\](?<message>.*(?:\n(?!\d+-\d+-\d+T).*)*)$/m';
$str = '2022-06-27T15:22:35.506+00:00 [Info] MSAT starting with 60000 tick ...
2022-06-27T15:22:35.506+00:00 [Info] pram[:9999] starting ...
2022-06-27T15:22:35.508+00:00 [Info] New settings received:
{"indexer.settings.compaction.days_of_week":"Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday","indexer.settings.compaction.interval":"00:00,00:00","indexer.settings.compaction.compaction_mode":"circular","indexer.settings.log_level":"info","indexer.settings.persisted_snapshot.interval":5000,"indexer.settings.compaction.min_frag":30,"indexer.settings.inmemory_snapshot.interval":200,"indexer.settings.max_cpu_percent":0,"indexer.settings.storage_mode":"forestdb","indexer.settings.recovery.max_rollbacks":5,"indexer.settings.memory_quota":1073741824,"indexer.settings.compaction.abort_exceed_interval":false}
2022-06-27T15:22:35.508+00:00 [Info] PROJ[:9999] settings notifier from metakv
';
preg_match_all($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