I remember reading (sorry, can't remember the source) that it's been proven mathematically that there's no way to write code which will run the same on any Turi

I remember reading (sorry, can't remember the source) that it's been proven mathematically that there's no way to write code which will run the same on any Turing-equivalent processor. Obviously that's not saying much since Bash is pretty far abstracted from the CPU, it's more of a caveat that I've hardly ever seen a discussion about Bash which doesn't involve at least one "well, actually" comment about how the suggested code doesn't do what the autor purports on some incredibly niche platform or with some highly unusual configuration.