system-config

system-config is a skill for Claude Code, Codex from bolivian-peru/os-moda. It costs 37 tokens per session (342 once invoked), scanned A, original, Apache-2.0.

A guide for reading and editing NixOS system settings. NixOS describes the whole system in configuration files and applies changes by creating numbered system versions.

In plain words
What is it for?
It helps inspect and change NixOS options, validate a proposed rebuild, apply approved changes, and manage earlier system versions.
Why use it?
It reduces the risk of changing a running system blindly by requiring configuration review, validation, visible differences, and a rollback path.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit It helps inspect and change NixOS options, validate a proposed rebuild, apply approved changes, and manage earlier system versions.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/bolivian-peru/os-moda/system-config
Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent
npx skills add bolivian-peru/os-moda --skill system-config
Clone the repo
git clone --depth 1 https://github.com/bolivian-peru/os-moda

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for system-config

README.md
[![agentmods](https://agentmods.dev/badge/skills/bolivian-peru/os-moda/system-config/github.svg)](https://agentmods.dev/skills/bolivian-peru/os-moda/system-config)
Your own site
<a href="https://agentmods.dev/skills/bolivian-peru/os-moda/system-config"><img src="https://agentmods.dev/badge/skills/bolivian-peru/os-moda/system-config/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for system-config

Your own site · 80×15
<a href="https://agentmods.dev/skills/bolivian-peru/os-moda/system-config"><img src="https://agentmods.dev/badge/skills/bolivian-peru/os-moda/system-config.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 37 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 342 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00037 $0.00342
Opus 5 $0.00018 $0.00171
Sonnet 5 $0.00007 $0.00068
Haiku 4.5 $0.00004 $0.00034

Measured 10d ago against content hash e1fd581fd8eb, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

system-config scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 10d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/system-config/SKILL.md · 48 lines

What it actually says

System Config Skill

You are the interface to NixOS configuration. Every system change goes through configuration.nix and is applied with nixos-rebuild.

Read Current Config

Read /etc/nixos/configuration.nix and any imported modules to understand current state.

Modify Config

  1. Read the current configuration
  2. Make the requested change
  3. Show the diff to the user
  4. Validate with dry-run rebuild
  5. On approval, apply with nixos-rebuild switch
  6. Record the change in memory

Enumerate Options

NixOS has thousands of configurable options. Help the user discover what's available:

  • nixos-option services.postgresql — show PostgreSQL module options
  • nixos-option networking — show networking options

Safety Rules

  • Always validate before applying changes
  • Always show diff before rebuilding
  • Never edit /etc/nixos/configuration.nix without explaining the change
  • Record every change in memory with the generation number
  • Know how to rollback if something breaks

Generation Management

Every rebuild creates a new generation. The user can always boot into any previous generation from the bootloader. This makes NixOS the safest OS for an AI to manage — you literally cannot permanently brick it.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 10d ago First seen · 48 lines · 37 tokens per session scan A e1fd581fd8eb

Subscribe to this mod's changes

system-config is a skill published in the GitHub repository bolivian-peru/os-moda (117 stars, last pushed 2mo ago), licensed Apache-2.0. It adds 37 tokens to every session and 342 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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