Process executes commands in sub-processes.

In this example, we run a simple directory listing and get the result back:

use Symfony\Component\Process\Process;

$process = new Process('ls -lsa');
$process->setTimeout(3600);
$process->run();
if (!$process->isSuccessful()) {
    throw new RuntimeException($process->getErrorOutput());
}

print $process->getOutput();

You can think that this is easy to achieve with plain PHP but it's not especially if you want to take care of the subtle differences between the different platforms.

And if you want to be able to get some feedback in real-time, just pass an anonymous function to the run() method and you will get the output buffer as it becomes available:

use Symfony\Component\Process\Process;

$process = new Process('ls -lsa');
$process->run(function ($type, $buffer) {
    if ('err' === $type) {
        echo 'ERR > '.$buffer;
    } else {
        echo 'OUT > '.$buffer;
    }
});

That's great if you want to execute a long running command (like rsync-ing files to a remote server) and give feedback to the user in real-time.

You can run the unit tests with the following command:

$ cd path/to/Symfony/Component/XXX/
$ composer.phar install --dev
$ phpunit