Essential Nix commands for Rust projects

Nix gives you reproducible Rust toolchains without polluting your system. The modern CLI splits responsibilities into four commands you will use repeatedly: nix develop, nix shell, nix run, and nix build.

Four commands, four intents: develop, consume, execute, package.

Why this matters for Rust

Nix replaces ad-hoc global tooling with per-project environments. Each project declares its toolchain in a flake or shell.nix, and Nix materializes it on demand.

nix develop: the project workspace

nix develop starts an interactive shell with the dependencies your project expects. It does not run your build automatically; it gives you the environment so you can run your own commands.

# Enter the default dev shell
nix develop

# Or enter a named shell
nix develop .#rust

Inside the shell, you can run:

cargo build
cargo clippy
cargo test

nix shell: the one-off tool

nix shell is for consuming tools without installing them globally.

# Run a single tool without global install
nix shell nixpkgs#cargo-watch
cargo-watch -x test

# Use a specific version
nix shell nixpkgs#cargo
cargo --version

nix run: execute without entering

nix run resolves and executes in one step.

# Run from nixpkgs
nix run nixpkgs#cargo-audit -- audit

# Run flake app outputs
nix run .
nix run .#my-cli -- --help

nix build: produce the artifact

nix build compiles and stores deterministic outputs in the Nix store.

# Build default package
nix build

# Build named package
nix build .#my-app

# Inspect linked result
ls -l ./result
./result/bin/my-app --version

The command matrix

Practical Rust workflow

# 1) Enter dev environment
nix develop

# 2) Build and test
cargo check --all-targets
cargo test
cargo build --release

# 3) Build package output
exit
nix build .#my-app

# 4) Run packaged output
nix run .#my-app

Core lesson: nix develop writes software, nix shell provides tools, nix run executes, and nix build ships.