$re = '/(?<=[\/=\[])([^\/=\[]+)(?=\])/m';
$str = '2016-02-17 19:59:18,182 GMT [transaction-Id=47ad8e96-1db8-4b41-85e5-9256fca485ab] [request_uri=/mydevice/2232234] [] INFO Response:{"executionTimeInMillis":54,"transactionId":"3191569800","success":false,"internalTransactionId":"47ad8e96-1db8-4b41-85e5-9256fca485ab","operationResults":[{"operation":"addDevice","code":"409","message":"Cannot add device"}]}';
preg_match_all($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