There’s documentation everywhere about nightly, and the software I am trying to use says it requires nightly, but for the life of me I can’t find a straight explanation of how to use nightly?
Note I have rustc and cargo but not Rustup as it does not run on Alpine Linux.
We don’t currently build distributions for x86_64-unknown-linux-musl, so you’ll have to see if whoever is creating the distribution you’re using now builds nightlies as well.
Rustup will run on your system, as long as you have internet connection, curl and a bash.
https://rustup.rs/
You don't need any superuser rights or anything else, because it installs it into your home dir. With that you can follow the instructions on GitHub - rust-lang/rustup: The Rust toolchain installer
Alpine Linux is MUSL-based rather than glibc-based. We don’t build a host toolchain for MUSL Linux right now.