jq

name	jq
description	Writes jq filters to query, reshape, aggregate, and pipeline JSON from APIs, CLIs, and logs. Use when parsing JSON, building jq one-liners, or explaining a jq expression. Not for in-memory DataFrames (pandas/polars), JSON Schema validation, or JavaScript Array.map as a jq substitute.
version	1.0.1
category	development
risk	safe
source	community
date_added	2026-03-28
tags	["jq","json","shell","cli","data-transformation","bash"]
tools	["claude","cursor","gemini"]

jq — JSON Querying and Transformation

Overview

jq is the standard CLI tool for querying and reshaping JSON. This skill covers practical, expert-level usage: filtering deeply nested data, transforming structures, aggregating values, and composing jq into shell pipelines. Every example is copy-paste ready for real workflows.

When to Use

• Parsing JSON output from APIs, CLI tools (AWS, GitHub, kubectl, docker), or log files
• Transforming JSON structure (rename keys, flatten arrays, group records)
• Building jq one-liners inside a bash script or PowerShell pipeline
• Explaining what a complex jq expression does
• Extracting specific fields from large JSON payloads for further processing

Prerequisites

• jq installed and on PATH. Verify with jq --version (requires ≥ 1.6 for walk, --stream stability).
• On Windows (PowerShell, primary host): install via winget install jqlang.jq or scoop install jq. The binary is jq.exe; all filter syntax is identical across platforms.
• On Linux/macOS: brew install jq or apt-get install jq.
• Familiarity with JSON data types (object, array, string, number, boolean, null).

Procedure

1. Basic Selection

# Extract a field
echo '{"name":"alice","age":30}' | jq '.name'
# "alice"

# Nested access
echo '{"user":{"email":"[e-mail]"}}' | jq '.user.email'

# Array index
echo '[10, 20, 30]' | jq '.[1]'
# 20

# Array slice
echo '[1,2,3,4,5]' | jq '.[2:4]'
# [3, 4]

# All array elements
  | jq