$re = '/^[A-Za-z]{3} +[A-Za-z]{3} +(?:[1-9]|[12]\d|3[01]) +(?:[01]\d|2[0-3]):[0-5]\d:[0-5]\d +(?:19|20)\d{2}\b/m';
$str = 'Thu Oct 1 23:01:00 2020 +00:00
LENGTH : \'275\'
ACTION :[7] \'CONNECT\'
DATABASE USER:[1] \'/\'
PRIVILEGE :[6] \'SYSDBA\'
CLIENT USER:[9] \'test_user\'
CLIENT TERMINAL:[5] \'pts/0\'
STATUS:[1] \'0\'
DBID:[10] \'1762369616\'
SESSIONID:[10] \'4294967295\'
USERHOST:[21] \'testdevserver\'
CLIENT ADDRESS:[0] \'\'
ACTION NUMBER:[3] \'100\'
Thu Oct 1 23:01:00 2020 +00:00
LENGTH : \'296\'
ACTION :[29] \'SELECT STATUS FROM V$INSTANCE\'
DATABASE USER:[1] \'/\'
PRIVILEGE :[6] \'SYSDBA\'
CLIENT USER:[9] \'test_user\'
CLIENT TERMINAL:[5] \'pts/0\'
STATUS:[1] \'0\'
DBID:[10] \'1762369616\'
SESSIONID:[10] \'4294967295\'
USERHOST:[21] \'testdevserver\'
CLIENT ADDRESS:[0] \'\'
ACTION NUMBER:[1] \'3\'';
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