wp-config debug to log file

/**
* For developers: WordPress debugging mode.
*
* Change this to true to enable the display of notices during development.
* It is strongly recommended that plugin and theme developers use WP_DEBUG
* in their development environments.
*/
define('WP_DEBUG', true); // or false
if (WP_DEBUG) {
   define('WP_DEBUG_LOG', true);
   define('WP_DEBUG_DISPLAY', false);
   @ini_set('display_errors',0);
}