AgentSkillsCN

nix-dev

利用评估与构建工具，开发并调试Nix表达式

SKILL.md
--- frontmatter
name: nix-dev
description: Develop and debug Nix expressions with evaluation and build tools
allowed-tools: Bash, Read, Write, Edit, Grep, Glob

Develop, debug, and iterate on Nix expressions.

Capabilities

This skill provides access to Nix tooling for development work:

  • •nix eval - Evaluate Nix expressions and inspect values
  • •nix build - Build derivations
  • •nix flake check - Validate flake
  • •nix flake show - Show flake outputs
  • •nix repl - Interactive exploration (use --expr for non-interactive)
  • •nix-instantiate - Debug derivations

Common Workflows

Evaluate an expression:

bash
nix eval .#nixosConfigurations.hostname.config.services.nginx.enable

Evaluate with JSON output:

bash
nix eval --json .#nixosConfigurations.hostname.config.networking.firewall.allowedTCPPorts

Debug a module option:

bash
nix eval .#nixosConfigurations.hostname.config.homelab --apply builtins.attrNames

Check derivation without building:

bash
nix-instantiate --eval -E 'with import <nixpkgs> {}; lib.version'

Build and check:

bash
nix build .#nixosConfigurations.hostname.config.system.build.toplevel --dry-run

Explore flake outputs:

bash
nix flake show --json | jq '.nixosConfigurations | keys'

Debugging Tips

Type errors:

bash
nix eval --show-trace .#problematic.expression

Infinite recursion:

bash
nix eval --show-trace --option eval-max-statements 100000 .#expression

Check option types:

bash
nix eval .#nixosConfigurations.host.options.services.nginx.enable.type.name

Rules

  • •Use --show-trace when debugging errors
  • •Use --json for machine-readable output
  • •Prefer nix eval over nix repl for scriptable operations
  • •Run nix flake check to validate after changes