Using jq

jq . file.json >/dev/null 2>&1 && echo "Valid" || echo "Invalid"

Using node

node -e "JSON.parse(require('fs').readFileSync(0,'utf8'))" < file.json


## Pretty Print

### Format JSON
```bash
# Python pretty print
python3 -m json.tool data.json

# jq pretty print
cat data.json | jq .

# Node pretty print
node -e "console.log(JSON.stringify(JSON.parse(require('fs').readFileSync(0,'utf8')), null, 2))" < data.json

Minify JSON

# Minify (remove whitespace)
cat data.json | jq -c .

# Python minify
python3 -c "import json,sys; print(json.dumps(json.load(sys.stdin)))" < data.json

Extract Data

Get Keys

# Top-level keys
cat data.json | jq 'keys'

# Nested keys
cat data.json | jq '.user | keys'

Get Values

# Get specific field
cat data.json | jq '.name'

# Get nested field
cat data.json | jq '.user.address.city'

# Get array elements
cat data.json | jq '.items[0]'

# Get all array items
cat data.json | jq '.items[]'

Filter Arrays

# Filter by value
cat data.json | jq '.items[] | select(.price > 100)'

# Map to specific field
cat data.json | jq '.items[] | .name'

# Count items
cat data.json | jq '.items | length'

Transform JSON

Rename Keys

# Rename 'name' to 'title'
cat data.json | jq '. + {title: .name} | del(.name)'

Add/Remove Fields

# Add field
cat data.json | jq '. + {newField: "value"}'

# Remove field
cat data.json | jq 'del(.unwantedField)'

# Update field
cat data.json | jq '.count += 1'

Merge Objects

# Merge two objects
echo '{}' | jq -s '.[0] * .[1]' file1.json file2.json

Convert Formats

JSON to CSV

# Simple JSON array to CSV
cat data.json | jq -r '.[] | [.name, .email, .age] | @csv'

# With header
echo "name,email,age" > output.csv
cat data.json | jq -r '.[] | [.name, .email, .age] | @csv' >> output.csv

CSV to JSON

# Using Python
python3 -c "
import csv, json, sys
reader = csv.DictReader(sys.stdin)
print(json.dumps(list(reader), indent=2))
" < data.csv

# Using jq (if dealing with array)
cat data.json | jq -c '.[]' | csvjson -d

JSON to YAML

# Using Python
python3 -c "
import json, yaml, sys
print(yaml.dump(json.load(sys.stdin)))
" < data.json

# Using yq
cat data.json | yq -y .

Query Examples

API Response Parsing

# Get array of IDs
curl -s api.example.com/data | jq '.[].id'

# Filter by status
curl -s api.example.com/data | jq '.[] | select(.status == "active")'

# Group by field
curl -s api.example.com/data | jq 'group_by(.category)'

Complex Queries

# Multiple fields
cat data.json | jq '{name: .user.name, email: .user.email}'

# Conditional
cat data.json | jq 'if .active then "active" else "inactive" end'

# Default values
cat data.json | jq '.name // "Unknown"'

Useful jq Flags

Flag	Description
`-r`	Raw output (no quotes)
`-c`	Compact output
`-M`	Monochrome
`-f`	Read filter from file
`-s`	Slurp (read all input)

Examples

Count items:

cat data.json | jq '.items | length'

Extract unique values:

cat data.json | jq '[.items[].category] | unique'

Sum values:

cat data.json | jq '[.items[].price] | add'

Convert to lines:

cat data.json | jq -c '.items[]'

json-tools

JSON Tools Skill

When to Use

Validate JSON

Check if Valid JSON