How to switch between Rust toolchains?

Question

rustup help toolchain lists the following sub-commands

SUBCOMMANDS:     list         List installed toolchains     install      Install or update a given toolchain     uninstall    Uninstall a toolchain     link         Create a custom toolchain by symlinking to a directory     help         Prints this message or the help of the given subcommand(s) 

I have the following toolchains installed

stable-x86_64-unknown-linux-gnu (default) nightly-2019-09-05-x86_64-unknown-linux-gnu nightly-x86_64-unknown-linux-gnu master 

I was trying to solve an issue for rust-clippy so I had to install the master toolchain. Even though stable is set as my default toolchain, my current toolchain is master and I would like to switch back to stable. How do I do it without uninstalling the master toolchain?

Is there no switch subcommand?

Answer 1

The rustup default stable command works well, but the easiest way is to keep a rust-toolchain file inside your project root folder. This is similar to a .nvm file for a NodeJS project.

rust-toolchain

nightly 

or

stable 

Answer 2

Use rustup default <toolchain> to change the default toolchain. You can use the full name (e.g. rustup default stable-x86_64-unknown-linux-gnu) or a short alias (e.g. rustup default stable).

rustup also has methods to override the default in a more scoped manner. See Overrides in the rustup book.