data-processing

A command-line guide for reading and changing structured files with jq and yq. jq handles JSON, while yq handles YAML and TOML, formats commonly used for application settings and deployment files.

In plain words
What is it for?
Use it to inspect files such as package.json, Docker Compose configurations, Kubernetes manifests, and GitHub Actions workflows.
Why use it?
It provides short commands for finding, filtering, transforming, counting, and updating structured configuration data. This avoids writing a custom script for routine file queries.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/0xdarkmatter/claude-mods/data-processing
Any agent
npx skills add 0xDarkMatter/claude-mods --skill data-processing
Clone the repo
git clone --depth 1 https://github.com/0xDarkMatter/claude-mods

Made for: Claude Code, Codex.

Per session 58 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 821 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00058 $0.00821
Opus 5 $0.00029 $0.00411
Sonnet 5 $0.00012 $0.00164
Haiku 4.5 $0.00006 $0.00082

Measured 2d ago against content hash 1b7b909734bd, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

data-processing 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 2d 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/data-processing/SKILL.md · 111 lines

How it starts

The opening of the file, as written. The whole thing — 111 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Data Processing

Query, filter, and transform structured data (JSON, YAML, TOML) efficiently from the command line.

Tools

Tool Command Use For
jq jq '.key' file.json JSON processing
yq yq '.key' file.yaml YAML/TOML processing

jq Essentials

# Extract single field
jq '.name' package.json

# Extract nested field
jq '.scripts.build' package.json

# Extract from array
jq '.dependencies[0]' package.json

# Extract multiple fields
jq '{name, version}' package.json

# Navigate deeply nested
jq '.data.users[0].profile.email' response.json

# Filter by condition
jq '.users[] | select(.active == true)' data.json

# Transform each element
jq '.users | map({id, name})' data.json

# Count elements
jq '.users | length' data.json

# Raw string output
jq -r '.name' package.json

yq Essentials

# Extract field
yq '.name' config.yaml

# Extract nested
yq '.services.web.image' docker-compose.yml

# List all keys
yq 'keys' config.yaml

# List all service names (Docker Compose)
yq '.services | keys' docker-compose.yml

# Get container images (K8s)
yq '.spec.template.spec.containers[].image' deployment.yaml

# Update value (in-place)
yq -i '.version = "2.0.0"' config.yaml

# TOML to JSON
yq -p toml -o json '.' config.toml

Quick Reference

Task jq yq
Get field jq '.key' yq '.key'
Array element jq '.[0]' yq '.[0]'
Filter array jq '.[] | select(.x)' yq '.[] | select(.x)'
Transform jq 'map(.x)' yq 'map(.x)'
Count jq 'length' yq 'length'
Keys jq 'keys' yq 'keys'
Pretty print jq '.' yq '.'
Compact jq -c yq -o json -I0
Raw output jq -r yq -r
In-place edit - yq -i

When to Use

  • Reading package.json dependencies
  • Parsing Docker Compose configurations
  • Analyzing Kubernetes manifests
  • Processing GitHub Actions workflows
  • Extracting data from API responses
  • Filtering large JSON datasets
  • Config file manipulation
  • Data format conversion

Read the full file on GitHub · 111 lines

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 2d ago First seen · 111 lines · 58 tokens per session scan A 1b7b909734bd

Subscribe to this mod's changes

data-processing is a skill published in the GitHub repository 0xDarkMatter/claude-mods (32 stars, last pushed 9d ago), licensed MIT. It adds 58 tokens to every session and 821 once invoked, about $0.0003 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.