yii\console\controllers\ServeController::actionIndex PHP Method

    public function actionIndex($address = 'localhost')
    {
        $documentRoot = Yii::getAlias($this->docroot);
        if (strpos($address, ':') === false) {
            $address = $address . ':' . $this->port;
        }
        if (!is_dir($documentRoot)) {
            $this->stdout("Document root \"{$documentRoot}\" does not exist.\n", Console::FG_RED);
            return self::EXIT_CODE_NO_DOCUMENT_ROOT;
        }
        if ($this->isAddressTaken($address)) {
            $this->stdout("http://{$address} is taken by another process.\n", Console::FG_RED);
            return self::EXIT_CODE_ADDRESS_TAKEN_BY_ANOTHER_PROCESS;
        }
        if ($this->router !== null && !file_exists($this->router)) {
            $this->stdout("Routing file \"{$this->router}\" does not exist.\n", Console::FG_RED);
            return self::EXIT_CODE_NO_ROUTING_FILE;
        }
        $this->stdout("Server started on http://{$address}/\n");
        $this->stdout("Document root is \"{$documentRoot}\"\n");
        if ($this->router) {
            $this->stdout("Routing file is \"{$this->router}\"\n");
        }
        $this->stdout("Quit the server with CTRL-C or COMMAND-C.\n");
        passthru('"' . PHP_BINARY . '"' . " -S {$address} -t \"{$documentRoot}\" {$this->router}");
    }