I'll confess I've never used `expect`, but I think `expect` is for interactive commands. I think if you were going to write retry logic in bash you would pipe it to `grep` and examine the return code. If `grep` doesn't find any matches, it'll exit with a status code of 1.

I'd never heard of the `wish` command shell (discussed briefly in that document) but you can always rely on the Tcl community to find a great pun.