jq¶

Output a JSON file, in pretty-print format

jq

Output all elements from arrays

(or all key-value pairs from objects) in a JSON file:

jq .[]

Use jq to pretty-print JSON

jq '.' file.json

Filter JSON object by extracting a specific field

jq '.fieldName' file.json

Filter JSON array to extract specific element by index

jq '.[<index>]' file.json

Select multiple fields from JSON

jq '{field1: .field1, field2: .field2}' file.json

Use jq to count the number of elements in an array

jq '.arrayName | length' file.json

Apply a function to each element in a JSON array

jq '.arrayName[] | .fieldName' file.json

Parse JSON from stdin

cat file.json | jq '.fieldName'

Use jq to filter JSON objects by condition

jq 'select(.fieldName == "value")' file.json

Modify JSON field value

jq '.fieldName = "newValue"' file.json

Load JSON from URL

curl -s "http://example.com/file.json" | jq '.fieldName'

Combine operations and select elements from different levels

jq '.[] | {id: .id, name: .info.name}' file.json

Query nested JSON data

jq '.outerField.innerField' file.json

Concatenate fields

jq '.field1 + " " + .field2' file.json

Group by a particular field

jq 'group_by(.fieldName)' file.json

Sort JSON objects by field

jq 'sort_by(.fieldName)' file.json

Use jq to find unique values

jq 'unique' file.json

Print keys and values of a JSON object

jq 'to_entries | .[] | "\(.key): \(.value)"' file.json

Output compact JSON without whitespace

jq -c '.' file.json

Use jq to delete a field

jq 'del(.fieldName)' file.json

Combine data from two JSON files

jq -s '.[0] + .[1]' file1.json file2.json

Read JSON objects from a file into an array, and output it

(inverse of jq .[]):

jq --slurp

Output the first element in a JSON file

jq .[0]

Output the value of a given key of the first element in a JSON file

jq .[0].key_name

Output the value of a given key of each element in a JSON file

jq 'map(.key_name)'

[ { foo: 1 }, { foo: 2 } ] => [1, 2] Extract as stream of values instead of a list

jq '.[] | .foo'

[ { "foo": 1 }, { "foo": 2 } ] => 1, 2 Slicing

jq '.[1:2]'

[ { "foo": 1 }, { "foo": 2 } ] => { "foo": 2 } Dictionary subset shorthand

jq 'map({ a, b })'

[ { "a": 1, "b": 2, "c": 3 }, ...] => [ { "a": 1, "b": 2 }, ...] Converting arbitrary data to json

jq -r '(map(keys) | add | unique | sort) as $cols \
        | .[] as $row | $cols | map($row[.]) | @csv'

[ { "foo": 1, "bar": 2}, { "foo": 3, "baz": 4}]

=> 2,,1 ,4,3 Filter a list of objects

jq 'map(select(.name == "foo"))'

[ { "name": "foo" }, { "name": "bar" } ] => [ { "name": "foo" } ]

mapping and transforming¶

Add + 1 to all items

jq 'map(.+1)'

Delete 2 items

jq 'del(.[1, 2])'

Concatenate arrays

jq 'add'

Flatten an array

jq 'flatten'

[[1], [2]] => [1, 2] Create a range of numbers

jq '[range(2;4)]'

Display the type of each item

jq 'map(type)'

Sort an array of basic type

jq 'sort'

[3, 2, 1] => [1, 2, 3] Sort an array of objects

jq 'sort_by(.foo)'

Sort lines of a file

jq --slurp '. | sort | .[]'

Group by a key - opposite to flatten

jq 'group_by(.foo)'

Minimum value of an array

jq 'min'

See also min, max, min_by(path_exp), max_by(path_exp)

Remove duplicates

jq 'unique'

or

jq 'unique_by(.foo)'

or

jq 'unique_by(length)'

[1, 1, 2, 1] => [1, 2] Reverse an array

jq 'reverse'

jq in shell scripts¶

URL Encode something

date | jq -sRr @uri

Thu%2021%20May%202020%2012%3A40%3A40%20PM%20CEST%0A

To create proper JSON from a shell script and properly escape variables:

jq -n --arg foobaz "$FOOBAZ" '{"foobaz":$foobaz}'

To fill environment variables from JSON object keys

(e.g. $FOO from jq query ".foo")

export $(jq -r '@sh "FOO=\(.foo) BAZ=\(.baz)"')

Input/output formats¶

Parsing json

jq 'with_entries(.value |= fromjson)' --sort-keys

{ "b": "{}", "a": "{}" } => { "a": {}, "b": {} } Serializing json

jq 'with_entries(.value |= tojson)' --sort-keys

{ "a": {}, "b": {} } => { "a": "{}", "b": "{}" } Converting to csv

jq '.[] | [.foo, .bar] | @csv' -r

[{ "foo": 1, "bar": 2, "baz":3 }] => 1,2 List all keys of an object:

jq 'keys' file.json

Slice an array from start to end index

jq '.[<start>:<end>]' file.json

Print selected fields joined as space-separated text

jq '.[] | [.field1, .field2] | join(" ")' file.json