Runs the process.
The callback receives the type of output (out or err) and some bytes from the output in real-time. It allows to have feedback from the independent process during execution.
The STDOUT and STDERR are also available after the process is finished via the getOutput() and getErrorOutput() methods.
@api
callback|null $callback A PHP callback to run whenever there is some: output available on STDOUT or STDERR
integer The exit status code
RuntimeException When process can't be launch or is stopped
public function run($callback = null) {
$this
->start($callback);
return $this
->wait($callback);
}