$devvkit learn --librarie jq-guide

jq Guide

[json][cli][data][parsing]

Universal

Install

# macOS
brew install jq

# Linux
sudo apt install jq

# Windows
winget install jq

jq is to JSON what sed is to text. It lets you slice, filter, map, and transform structured data with a concise DSL.

The . operator walks into objects, [] indexes arrays, and pipes (|) feed one filter into the next. jq queries become as natural as grep patterns.

Basic Selection

Pretty-print· Format raw JSON with indentation.

cat data.json | jq .

Access property· Extract a top-level field.

cat data.json | jq .name

Nested access· Walk into nested objects.

cat data.json | jq .user.address.city

Array indexing· Get the first element.

cat data.json | jq .items[0]

Array slicing· Get a subset.

cat data.json | jq .items[2:5]

Select by condition· Filter array elements.

cat data.json | jq '.[] | select(.age > 18)'

Map field· Extract one field from all elements.

cat data.json | jq '[.[] | .name]'

Add computed field· Create new fields.

cat data.json | jq '[.[] | {name, isAdult: (.age >= 18)}]'

Merge objects· Combine objects.

cat data.json | jq '.[] | {name} + {status: "active"}'

Raw output· Output without quotes.

cat data.json | jq -r .name

Compact output· No newlines or indentation.

cat data.json | jq -c .items

CSV output· Convert to CSV rows.

cat data.json | jq -r '.[] | [.name, .age] | @csv'