jq

jq is a lightweight and flexible command-line JSON processor.

Filter on Object key/value

Select the array in .items, loop through and select the items which have a .name equal to "thisname", then return the .name and .status

cat file.json | jq '.items | .[] | select(.name == "thisname") | {name: .name, status: .status}'

Sort and diff JSON filed

Use the --sort-keys flag to sort the files and then compare using diff

diff <(cat /tmp/A.json | jq --sort-keys) <(cat /tmp/B.json | jq --sort-keys)

Filter on Object key/value (contains)

Loop through an array and select the items which have a .name which contains "someText", then return the .name and .status

cat file.json | jq '.[] | select( .name | contains("someText") ) | {name: .name, status: .status}'

Filter on Object key existing

Select the array in .items, loop through and select the items which have the specified key, then return the .name

cat file.json | jq -r '.items | .[] | select(.a.path.to.an.array[]?.key != null) | .name'

Filter with multiple conditions

Use or in a select statement, to filter on multiple conditions

cat file.json | jq -r '.items | .[] | select((.status == "Running") or (.status == "Scheduled") or .status == "ConfirmationNeeded") | .name'

Filter on Object key/value (not contains)

Loop through an array and select the items which don’t have a .name which contains "some-text", then return the .name.

cat file.json | jq -r '.items | .[] | select(.name | contains("some-text") | not) | .name'

Filter Key with startswith

echo '{"items": [{"hostname": "aThing"}, {"hostname": "aThing2"}, {"hostname": "bThing"}]}' | jq -r '.items | .[] | select(.hostname | startswith("aT"))'

Filter Key with endswith

echo '{"items": [{"hostname": "aThing1"}, {"hostname": "aThing2"}, {"hostname": "bThing1"}]}' | jq -r '.items | .[] | select(.hostname | endswith("ing1"))'

Get length of an array

cat file.json | jq -r '.items | length'

Group by and count

echo '{"items": [ {"Priority": "High"},{"Priority": "High"},{"Priority": "High"},{"Priority": "High"},{"Priority": "Low"},{"Priority": "Low"},{"Priority": "Low"} ]}' | jq -r '.items | group_by(.Priority)[] | {Priority: .[0].Priority, Count: length}'
(out){
(out)  "Priority": "High",
(out)  "Count": 4
(out)}
(out){
(out)  "Priority": "Low",
(out)  "Count": 3
(out)}

Select, Group by and count

echo '{"items": [ {"Priority": "High"},{"Priority": "High"},{"Priority": "High"},{"Priority": "High"},{"Priority": "Medium"},{"Priority": "Medium"},{"Priority": "Low"},{"Priority": "Low"},{"Priority": "Low"} ]}' | jq -r '.items | .[] | select((.Priority == "High") or (.Priority == "Medium"))' | jq -s 'group_by(.Priority)[] | {Priority: .[0].Priority, Count: length}'
(out){
(out)  "Priority": "High",
(out)  "Count": 4
(out)}
(out){
(out)  "Priority": "Medium",
(out)  "Count": 2
(out)}

Select fields starting with

Select all fields that start with prefixA, from within the anotherField object

echo '{"aField": {}, "anotherField": { "prefixAOne": "foo", "prefixATwo": "foo", "prefixAThree": "foo", "prefixBOne": "bar", "prefixBTwo": "bar" }, "lastField": true}' | jq -r '.anotherField | to_entries[] | select(.key|startswith("prefixA"))'
(out){
(out)  "key": "prefixAOne",
(out)  "value": "foo"
(out)}
(out){
(out)  "key": "prefixATwo",
(out)  "value": "foo"
(out)}
(out){
(out)  "key": "prefixAThree",
(out)  "value": "foo"
(out)}

Add a field to an object

Assign bar to argument foo and then add the "foo": "bar" key/value to the object

echo '{"hello": "world"}' | jq --arg foo bar '. + {foo: $foo}'
(out){
(out)  "hello": "world",
(out)  "foo": "bar"
(out)}

Preserve nested objects with *

echo '{"hello": {"value": "world"}}' | jq '. * {"hello": {foo: ("bar")}}'
(out){
(out)  "hello": {
(out)    "value": "world",
(out)    "foo": "bar"
(out)  }
(out)}

Using + will not preserve nested objects

echo '{"hello": {"value": "world"}}' | jq '. + {"hello": {foo: ("bar")}}'
(out){
(out)  "hello": {
(out)    "foo": "bar"
(out)  }
(out)}

Concat strings

echo '{"hello": {"value": "world"}}' | jq --arg foo bar '. * {"hello": {foo: ("not" + $foo)}}'
(out){
(out)  "hello": {
(out)    "value": "world",
(out)    "foo": "notbar"
(out)  }
(out)}