Process, filter, and transform JSON data using jq - the lightweight and flexible command-line JSON processor.
Process, filter, and transform JSON data with jq.
# Extract a field
echo '{"name":"Alice","age":30}' | jq '.name'
# Output: "Alice"
# Multiple fields
echo '{"name":"Alice","age":30}' | jq '{name: .name, age: .age}'
# Array indexing
echo '[1,2,3,4,5]' | jq '.[2]'
# Output: 3
# Map over array
echo '[{"name":"Alice"},{"name":"Bob"}]' | jq '.[].name'
# Output: "Alice" "Bob"
# Filter array
echo '[1,2,3,4,5]' | jq 'map(select(. > 2))'
# Output: [3,4,5]
# Length
echo '[1,2,3]' | jq 'length'
# Output: 3
# Pretty print JSON
cat file.json | jq '.'
# Compact output
cat file.json | jq -c '.'
# Raw output (no quotes)
echo '{"name":"Alice"}' | jq -r '.name'
# Output: Alice
# Sort keys
echo '{"z":1,"a":2}' | jq -S '.'
# Select with conditions
jq '[.[] | select(.age > 25)]' people.json
# Group by
jq 'group_by(.category)' items.json
# Reduce
echo '[1,2,3,4,5]' | jq 'reduce .[] as $item (0; . + $item)'
# Output: 15
# Read from file
jq '.users[0].name' users.json
# Multiple files
jq -s '.[0] * .[1]' file1.json file2.json
# Modify and save
jq '.version = "2.0"' package.json > package.json.tmp && mv package.json.tmp package.json
Extract specific fields from API response:
curl -s https://api.github.com/users/octocat | jq '{name: .name, repos: .public_repos, followers: .followers}'
Convert CSV-like data:
jq -r '.[] | [.name, .email, .age] | @csv' users.json
Debug API responses:
curl -s https://api.example.com/data | jq '.'
-r for raw string output (removes quotes)-c for compact output (single line)-S to sort object keys--arg name value to pass variablesjq '.a' | jq '.b'Full manual: https://jqlang.github.io/jq/manual/ Interactive tutorial: https://jqplay.org/