How can i inject dependencies to Symfony Console commands?

use Symfony\Bundle\FrameworkBundle\Command\ContainerAwareCommand;

Extends your Command class from ContainerAwareCommand and get the service with $this->getContainer()->get('my_service_id');

Since Symfony 4.2 the ContainerAwareCommand is deprecated. Use the DI instead.

namespace App\Command;

use Symfony\Component\Console\Command\Command;
use Doctrine\ORM\EntityManagerInterface;

final class YourCommand extends Command
{
    /**
     * @var EntityManagerInterface
     */
    private $entityManager;

    public function __construct(EntityManagerInterface $entityManager)
    {
        $this->entityManager = $entityManager;

        parent::__construct();
    }

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        // YOUR CODE
        $this->entityManager->persist($object1);    
    }
}

It is best not to inject the container itself but to inject services from the container into your object. If you're using Symfony2's container, then you can do something like this:

MyBundle/Resources/config/services (or wherever you decide to put this file):

...
    <services>
        <service id="mybundle.command.somecommand" class="MyBundle\Command\SomeCommand">
        <call method="setSomeService">
             <argument type="service" id="some_service_id" />
        </call>
        </service>
    </services>
...

Then your command class should look like this:

<?php
namespace MyBundle\Command;

use Symfony\Component\Console\Command\Command;
use Symfony\Component\Console\Input\InputArgument;
use Symfony\Component\Console\Input\InputInterface;
use Symfony\Component\Console\Input\InputOption;
use Symfony\Component\Console\Output\OutputInterface;
use The\Class\Of\The\Service\I\Wanted\Injected;

class SomeCommand extends Command
{
   protected $someService;
   public function setSomeService(Injected $someService)
   {
       $this->someService = $someService;
   }
...

I know you said you're not using the dependency injection container, but in order to implement the above answer from @ramon, you have to use it. At least this way your command can be properly unit tested.

You can use ContainerCommandLoader in order to provide a PSR-11 container as follow:

require 'vendor/autoload.php';

$application = new Application('my-app', '1.0');

$container = require 'config/container.php';

// Lazy load command with container
$commandLoader = new ContainerCommandLoader($container, [
    'app:change-mode' => ChangeMode::class,
    'app:generate-logs' => GenerateLogos::class,
]);

$application->setCommandLoader($commandLoader);

$application->run();

ChangeMode class could be defined as follow:

class ChangeMode extends Command
{

    protected static $defaultName = 'app:change-mode';

    protected $container;

    public function __construct(ContainerInterface $container)
    {
        $this->container = $container;
        parent::__construct(static::$defaultName);
    }
...

NB.: ChangeMode should be provided in the Container configuration.