Laravel logging configuration to send logs to PHP error log. (>= Laravel 5.6)

logging.php

/*
|--------------------------------------------------------------------------
| Log Channels
|--------------------------------------------------------------------------
|
| Here you may configure the log channels for your application. Out of
| the box, Laravel uses the Monolog PHP logging library. This gives
| you a variety of powerful log handlers / formatters to utilize.
|
| Available Drivers: "single", "daily", "slack", "syslog",
|                    "errorlog", "custom", "stack"
|
*/

'channels' => [
    'stack' => [
        'driver' => 'stack',
        'channels' => ['single', 'errorlog'],
    ],
 ....
]