How can I debug my command controller? - typo3

Question

I have created a command controller and registered it on my scheduler, like:
$GLOBALS['TYPO3_CONF_VARS']['SC_OPTIONS']['extbase']['commandControllers'][] =
'Blog\\Events\\Command\\UpdateCommandController';
I can execute my command with the scheduler; but, if I enter a var_dump or die in my UpdateCommandController, I will not see any change in TYPO3 backend.
How can debug my command controller. And, what is the correct way to do this?
Can someone give me a tip?
Here is command controller, which i will to debug:
namespace Blog\Events\Command;
use TYPO3\CMS\Extbase\Mvc\Controller\CommandController;
class UpdateCommandController extends CommandController
{
/**
* Eventsrepository
*
* #var \Blog\Events\Domain\Repository\EventsRepository
* #inject
*/
protected $eventsRepository;
public function updateCommand()
{
echo "hello world";
}
}

Answer 1

You can debug the controller by calling it from the command line. To do this, you need a backend user _cli_lowlevel (with no privileges).
Then you can execute the script typo3/cli_dispatch.phpsh using php. To execute your command controller, you need to execute a command similar to this:
php typo3/cli_dispatch.phpsh extbase <controller-name>:<action-name>
Both <controller-name> and <action-name> would be update in your case. To see all available actions from CommandControllers, execute this command:
php typo3/cli_dispatch.phpsh extbase help

Answer 2

You can use Typo3 extension Developer Log for debuging.
Extension create log records in the database and show them in backend module.
Example of use in Extbase PHP code:
$arguments = 'any-data-for-log';
\TYPO3\CMS\Core\Utility\GeneralUtility::devlog(
'[ClassName::functionName]',
'extension_name',
1, // severity
array('arguments' => $arguments) // log data
);
This is a better way (for me).

Answer 3

In TYPO3 9 and above you can log like this:
$this->logger = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance(\TYPO3\CMS\Core\Log\LogManager::class)->getLogger(__CLASS__);
$logWriter = \TYPO3\CMS\Core\Utility\GeneralUtility::makeInstance('TYPO3\CMS\Core\Log\Writer\FileWriter', ['logFile' => 'typo3temp/logs/my_import.log']);
$this->logger->addWriter(\TYPO3\CMS\Core\Log\LogLevel::INFO, $logWriter);
and then
$this->logger->error($e->getMessage());