Formatting JSON Data Using JQ in Shell Scripting

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In this note, we will explore how to format JSON data using JQ.

Formatting JSON Data

JQ provides several functions for formatting JSON data. These functions can be used to pretty-print JSON data, compact JSON data, and to create new JSON objects from existing JSON data.

1. Pretty-Printing JSON Data

Pretty-printing JSON data is the process of adding indentation and line breaks to JSON data to make it more human-readable. JQ provides the . operator to pretty-print JSON data. Consider the following JSON data:

{
  "name": "John",
  "age": 25,
  "address": {
    "city": "New York",
    "state": "NY"
  }
}

To pretty-print this JSON data, we can use the following command:

jq '.' data.json

This will output the following JSON data:

{
  "name": "John",
  "age": 25,
  "address": {
    "city": "New York",
    "state": "NY"
  }
}

2. Compacting JSON Data

Compacting JSON data is the process of removing all unnecessary whitespace and line breaks from JSON data to make it more compact. JQ provides the -c option to compact JSON data. Consider the following JSON data:

{
  "name": "John",
  "age": 25,
  "address": {
    "city": "New York",
    "state": "NY"
  }
}

To compact this JSON data, we can use the following command:

jq -c '.' data.json

This will output the following JSON data:

{"name":"John","age":25,"address":{"city":"New York","state":"NY"}}

3. Creating New JSON Objects

JQ provides several functions for creating new JSON objects from existing JSON data. For example, we can use the map function to create a new JSON object that contains only the keys we want. Consider the following JSON data:

{
  "name": "John",
  "age": 25,
  "address": {
    "city": "New York",
    "state": "NY"
  }
}

To create a new JSON object that only contains the name and age keys, we can use the following command:

jq '{name, age}' data.json

This will output the following JSON data:

{
  "name": "John",
  "age": 25
}

We can also use the map function to transform the values of keys in a JSON object. For example, consider the following JSON data:

{
  "name": "John",
  "age": 25,
  "address": {
    "city": "New York",
    "state": "NY"
  }
}

To transform the name key to uppercase, we can use the following command:

jq '{name: .name | ascii_upcase, age}' data.json

This will output the following JSON data:

{
  "name": "JOHN",
  "age": 25
}

Also, see the example code shell-scripting-examples in our GitHub repository. See complete examples in our GitHub repositories.

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