Rustup

what rustup is and what it does for rust

Rust is installed and managed with the rustup tool. There are some concepts underlying how the tool works, including its role as a toolchain multiplexer.

rustup's role as a toolchain multiplexer

A toolchain represents a full installation of a Rust compiler (rustc) and related tools (like cargo).  Rustup enables switching between multiple versions of these tools which can be selected dynamically.

analogies in wider programming pantheon

rustup is similar to pyenv.