rustup-show

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$ rustup show

$ rustup show active-toolchain

$ rustup show home

rustup show

The `rustup-show` command, commonly invoked as `rustup show`, provides a concise summary of the currently active Rust toolchain and its installed components. It's a fundamental diagnostic tool for understanding your Rust development environment. The output typically includes the `rustup` home directory, the actively used toolchain (e.g., stable-x86_64-unknown-linux-gnu), and a list of installed components such as `rustc`, `cargo`, `rust-std`, `rust-docs`, and `rust-src`. This command is invaluable for verifying which Rust version you are using, troubleshooting environment issues, or simply getting an overview of your setup without needing to remember detailed configuration paths. It helps confirm that `rustup` is correctly managing your installations and that the expected toolchain is active for your current project or session.

The output reflects the active toolchain for the current shell session or directory. If you have toolchain overrides set via a `rust-toolchain.toml` file in the current directory or an `RUSTUP_TOOLCHAIN` environment variable, `rustup show` will display that specific overridden toolchain, not necessarily the global default. This is by design to accurately show the active environment, but it's important to be aware of how overrides can affect the displayed information.

The `rustup show` command is frequently used for:
Verifying Current Toolchain: Quickly confirm which Rust toolchain is active.
Troubleshooting: Diagnose issues related to incorrect Rust versions or missing components.
Environment Overview: Get a snapshot of your `rustup` configuration, home directory, and installed components.

A typical output from `rustup show` includes:
rustup home: /path/to/rustup/home
toolchain: (default) or (override)
host:
release:
installed components:
- ()
...

The `rustup` tool, which encapsulates the `show` subcommand, was developed to streamline the management of Rust toolchains across different platforms. It emerged as a successor to earlier, less comprehensive toolchain managers like `multirust`. The `show` command has been an integral part of `rustup` since its initial public releases, providing an immediate and essential overview of the installed Rust environment. Its straightforward utility for confirming the active toolchain and installed components has made it a foundational command for all Rust developers, consistently serving as a first point of inquiry for understanding their Rust setup.

rustup(1), rustup-toolchain(1), rustup-default(1), rustc(1), cargo(1)