Callback when tests are done

Currently when I run my tests, I run

$ rspec spec/ -cf nested

Is there a way to have a callback that when this task is done running, I
can hook into how many tests failed, or how many passed, and have my own
code run right after?

Right now I’m just using an at_exit {} and putting some stuff in there,
but I don’t know how to access the final results as a variable, or if
rspec has this built in already.