think\Process::getDescriptors PHP Method

    private function getDescriptors()
    {
        if ('\\' === DS) {
            $this->processPipes = WindowsPipes::create($this, $this->input);
        } else {
            $this->processPipes = UnixPipes::create($this, $this->input);
        }
        $descriptors = $this->processPipes->getDescriptors($this->outputDisabled);
        if (!$this->useFileHandles && $this->enhanceSigchildCompatibility && $this->isSigchildEnabled()) {
            $descriptors = array_merge($descriptors, [['pipe', 'w']]);
            $this->commandline = '(' . $this->commandline . ') 3>/dev/null; code=$?; echo $code >&3; exit $code';
        }
        return $descriptors;
    }