Efficiently\Larasset\Commands\AssetsCommand::copyCommand PHP Method

    protected function copyCommand()
    {
        $sys = strtoupper(PHP_OS);
        if (substr($sys, 0, 3) == "WIN") {
            $copyCommand = "xcopy";
        } elseif ($sys == "LINUX") {
            $copyCommand = "cp";
        } else {
            $copyCommand = "cp";
            // MacOS
        }
        return $copyCommand;
    }