nixkil

Agent skill for Nix language programming, Nix package manager, and NixOS.

CLI Commands

This skill provides knowledge and guidance for working with Nix. Use the standard Nix CLI tools directly via shell commands.

Package Management

# Search for packages
nix search nixpkgs <query>
nix search nixpkgs python --json  # JSON output for parsing

# Get package info
nix eval nixpkgs#<package>.meta --json

# Run a package without installing
nix run nixpkgs#<package> -- [args]

# Enter a shell with packages
nix shell nixpkgs#pkg1 nixpkgs#pkg2

# Build a package
nix build nixpkgs#<package>

Flake Operations

# Initialize a new flake
nix flake init
nix flake init --template templates#<name>

# Show flake outputs
nix flake show [flake-ref]
nix flake show --json  # JSON output

# Check/validate a flake
nix flake check [flake-ref]

# Update flake inputs
nix flake update [flake-ref]
nix flake update <input-name> [flake-ref]  # Update specific input

# Show lock file info
nix flake metadata [flake-ref]

NixOS Configuration

# Search NixOS options (use nixos.org/options or)
nix eval --expr 'builtins.attrNames (import <nixpkgs/nixos> {}).options'

# Rebuild system (requires sudo)
sudo nixos-rebuild switch
sudo nixos-rebuild switch --flake .#hostname
sudo nixos-rebuild test  # Test without making it default
sudo nixos-rebuild boot  # Activate on next boot

# List generations
nix-env --list-generations -p /nix/var/nix/profiles/system

Language Tools

# Evaluate Nix expressions
nix eval --expr '1 + 1'
nix eval --file ./file.nix
nix eval .#someOutput --json

# Format Nix files (nixfmt or alejandra)
nix fmt  # Uses formatter from flake
nixfmt file.nix
alejandra file.nix

# Lint Nix files
statix check .
deadnix .

# Parse/validate syntax
nix-instantiate --parse file.nix

Useful Flags

• --json - Output as JSON for parsing
• --verbose / -v - Show more details
• --dry-run - Show what would be done
• --show-trace - Show full error traces
• --impure - Allow impure evaluation (env vars, etc.)

Knowledge Areas

| Area | Topics | |------|--------| | nix-language | Syntax, types, functions, builtins, derivations | | nixpkgs | Package overrides, overlays, cross-compilation | | flakes | Structure, inputs/outputs, commands, templates | | devenv | Development environments with services and pre-commit hooks | | nixos | System configuration, modules, services | | nix-darwin | macOS configuration with Nix | | home-manager | User environment and dotfiles management | | macos-linux-builder | Building Linux packages on macOS | | troubleshooting | Common errors and solutions |

Examples

DevShell Examples

• examples/devshells/golang/ - Go development environment
• examples/devshells/python/ - Python with venv and tooling
• examples/devshells/rust/ - Rust with cargo tools
• examples/devshells/nodejs/ - Node.js with TypeScript
• examples/devshells/java/ - Java with Maven and Gradle
• examples/devshells/multi-lang/ - Multiple languages in one flake

Devenv Examples

• examples/devenv/basic/ - Basic devenv setup
• examples/devenv/with-services/ - PostgreSQL, Redis services
• examples/devenv/with-precommit/ - Pre-commit hooks configuration