Expect is such a great tool for a specific class of problem. Decades ago I worked as a test engineer for a big hardware vendor. We had maybe a couple hundred raid controllers that we were testing and to address some issues we found, the supplier needed us to change a bunch of configuration variables that were only accessible via a text menu system over a serial connection to these devices. After painful manual reconfiguration of a handful of these things, I instead wrote a fairly complex expect script to make the appropriate changes and also validate all the settings on the rest of the raid controllers in a fraction of the time it would have taken to do it manually. It saved me so much hassle and got me some pretty good kudos and respect from my direct leads. It's one of those tools that I kind of wish I would need to use again!