process-3.3.php

<?php
<<<CONFIG
packages:
    - "symfony/process: 3.3.x-dev"
CONFIG;

use Symfony\Component\Process\Process;
use Symfony\Component\Process\ProcessBuilder;

$executable = 'echo';
$arguments = ['test1', 'test2'];

$processBuilder = new ProcessBuilder();
$processBuilder->setArguments(array_merge(
    [$executable],
    $arguments
));
$process = $processBuilder->getProcess();

if (DIRECTORY_SEPARATOR !== '\\') {
    $process->setCommandLine('exec ' . $process->getCommandLine());
}

$process->mustRun(function ($type, $buffer) {
    echo $buffer;
});