> ... but I don't actually know what system in the past decade (or more) wouldn't have bash. There's some ambiguity about "have bash". If "having" bash means t

> ... but I don't actually know what system in the past decade (or more) wouldn't have bash. There's some ambiguity about "have bash". If "having" bash means that (some version of) bash has been ported to the system, there are indeed very few. If "having" means that bash (supporting all options that you need) is available to the user, that could be a lot more. As others have noted, the BSDs, Android and many embedded Linux systems don't come with bash pre-installed, MacOS pre-installed bash is stuck at version 3.2 (which doesn't have associative arrays), and the user could be in an environment that does not allow them to install whatever they need.