Rust "rustup: command not found" in CI

By Kaveh Alemi·Latchkey

The shell could not find rustup (or cargo) on PATH. Either Rust was never installed on the runner, or it is installed but ~/.cargo/bin was never added to PATH for this step.

What this error means

A step calling rustup or cargo fails instantly with "command not found", even on an image that supposedly has Rust. Common on bare images or after installing rustup in a previous step without exporting PATH.

./ci/build.sh: line 3: rustup: command not found
# or
cargo: command not found

Diagnose it: toolchain, features, cache

rustc --version --verbose && cargo --version
cat rust-toolchain.toml 2>/dev/null
cargo tree -e features | head -30
cargo clean && cargo build --locked

Common causes

Rust not installed on the runner

A minimal base image ships no Rust toolchain. rustup and cargo simply do not exist until you install them.

~/.cargo/bin not on PATH

rustup installs binaries to ~/.cargo/bin. If that directory isn’t on PATH - or a later step starts a fresh shell that never sourced ~/.cargo/env - the commands aren’t found.

How to fix it

Install rustup and add it to PATH

curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
. "$HOME/.cargo/env"
rustc --version

Persist cargo bin to the job PATH

In GitHub Actions, write ~/.cargo/bin to $GITHUB_PATH so every later step finds cargo.

- run: |
    curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
    echo "$HOME/.cargo/bin" >> "$GITHUB_PATH"
- run: cargo build   # now resolves

How to prevent it

• Use a setup action (e.g. dtolnay/rust-toolchain) instead of installing by hand.
• Add ~/.cargo/bin to $GITHUB_PATH so all steps see cargo.
• Use the official rust Docker image when you control the container.

Frequently asked questions

Related guides

References

• The Cargo Book
• GitHub Actions documentation