Migrate to Bash (or Nushell) for scripting

[bakaq]

We have already hit many of the kinks that pure POSIX sh has. I'm seriously considering using bash as the shell for scripting instead. This solves many portability issues, gives us access to good features like arrays, and it's much easier to find documentation about. I don't think it hurts portability too much, as most UNIX systems come with it preinstalled (shout out to exceptions like Alpine or some BSDs) and in basically all of them it is very easy to install. Nix uses bash instead of sh exactly for this reason.

Alternatives to think about:

• Going straight to Nushell, which has the huge benefits of being an actually sane programming language and of supporting Windows. Obvious con is that it's not preinstalled in any system really, and I don't think it's fair to have that randomly as a dependency. It would be really nice though, and I think we should seriously consider it at least for the justfiles.
• Python. Just no. It's basically the points above for Nushell but worse in every way possible.
• Not having this problem Do an actual Rust binary instead of mountains of POSIX shell #41.

[constraintAutomaton]

Does Node.js could make sense? But personally I think bash or nushell would make the most sense.

[triska]

It is my hope that you choose a language that generates a lot of joy and excitement when using it, and also attracts interesting contributors!

Nushell seems like an excellent candidate for this, and its use may also motivate an eventual Prolog implementation of it! It seems it is also easy to install?

[bakaq]

Another downside of Nushell I can think of right now is that it is still a bit unstable, so it may get annoying for users to get the exact version that is needed for Bakage to work. This could be solved by frequently releases of Bakage and always requiring the latest Nushell version, which I believe is a fair requirement to have.