bash and curl question

im telling curl to download a range of files, like `curl -Of www.foo.com/bar[000-999].log` and id like to have two separate counters in bash, one for attempted downloads, and another for successful downloads, so i can calculate a success rate at the end of the downloading. how would i do this?

what i'm really trying to figure out, though, is how to figure out when curl is successful. i can get the attmpted counter working, but i'm not sure how to get the success counter to work