private function pull()
    {
        if (is_writable(dirname($this->installDir))) {
            $cmd = new Command('mkdir');
            $cmd->addFlag('p')
                ->addParam($this->installDir);
            if ($this->ex($cmd)) {
                $cmd = new Command('cd');
                $cmd->addParam($this->installDir)
                    ->addSubCommand('&&')
                    ->addSubCommand('git')
                    ->addSubCommand('clone')
                    ->addParam($this->repoUrl)
                    ->addParam('.');

                return $this->ex($cmd);
            }
        }

        return false;
    }