tldr/pages/common/rustup-which.md

rustup which

Display which binary will be run for a command managed by rustup. Like which, but searches a Rust toolchain instead of $PATH. More information: https://rust-lang.github.io/rustup.

• Display the path to the binary in the default toolchain:

rustup which {{command}}

• Display the path to the binary in the specified toolchain (see rustup help toolchain for more information):

rustup which --toolchain {{toolchain}} {{command}}