如何将参数传递给PHP exec（）

I am using the following code to run the function in background.

function execInBackground($cmd) {
    if (substr(php_uname(), 0, 7) == "Windows"){
        pclose(popen("start /B ". $cmd, "r")); 
    }
    else {
        exec($cmd . " > /dev/null 2>&1 &");  
    }
}

$cmd = execInBackground("http://example.com/parentdesc/frontend/web/index.php?r=site%2Ftest");

It is working fine. But how can I pass the parameters to the exec?

I tried:

$cmd = execInBackground("http://example.com/parentdesc/frontend/web/index.php?r=site%2Ftest \"param1\" \"param2\" ");

And in my function I print the $argv. But it doesn't have any values in it.

My function:

public function actionTest()
{
    // does not have anything           
    print_r($argv);
   // here is my mail sending logic
}

Am I missing something?