//在入口bootstrap/App.php中

$env = $app->detectEnvironment(

    function () use ($app) {

        $uname = php_uname('n');

        $environment = 'local';

        switch ($uname) {

            case 'xxx1':

            case 'xxx2':

                $environment = 'production';

                break;

            case 'xxx3':

                $environment = 'testing';

                break;

            default:

                $environment = 'local';

                break;

        }

        putenv("APP_ENV={$environment}");

        (new \Dotenv\Dotenv($app->basePath(), ".env.{$environment}"))->load();

    }

);