I have been looking for something like this this for a while and this would be ideal for what I want. But when I run the script, it just says: testing sd card read/write speed. please wait a few minutes.
But I get no result. I have waited for 10 minutes and nothing apart from full cpu usage. Any ideas?

Edit: I have just tried three different sd cards and I know they all work, but I don't get a result for any of them.