Use jq for JSON Processing

jq is a powerful command-line JSON processor that allows you to parse, filter, and manipulate JSON data.

Sample JSON File

For the examples in this guide, we'll be using a sample JSON file named largefile.json. Here's the structure of this file:

{
  "users": [
    {
      "name": "John Doe",
      "age": 30,
      "city": "New York",
      "hobbies": [
        "reading",
        "swimming",
        "cycling"
      ],
      "address": {
        "street": "123 Main St",
        "zip": "10001"
      }
    },
    {
      "name": "Jane Smith",
      "age": 28,
      "city": "Los Angeles",
      "hobbies": [
        "painting",
        "yoga",
        "traveling"
      ],
      "address": {
        "street": "456 Oak Ave",
        "zip": "90001"
      }
    }
  ]
}

Install jq

If you don't have jq installed, you can install it using:

Ubuntu/Debian:

Package manager:

Package name:

Install jq on Ubuntu/Debian

sudo apt-get install jq

macOS (using Homebrew):

Package manager:

Package name:

Install jq on macOS

brew install jq

Explore the Structure

To get an overview of the JSON structure:

Input file:

Pretty-print JSON

jq '.' largefile.json

Sample Output:

{
  "name": "John Doe",
  "age": 30,
  "city": "New York",
  "hobbies": [
    "reading",
    "swimming",
    "cycling"
  ],
  "address": {
    "street": "123 Main St",
    "zip": "10001"
  }
}

View Specific Keys

To view specific keys or values:

Key name:

Input file:

View specific key

jq '.name' largefile.json

Sample Output:

"John Doe"

For nested keys:

Parent key:

Child key:

Input file:

View nested key

jq '.address.street' largefile.json

Sample Output:

"123 Main St"

Search and Filter Data

To filter out specific data:

Key name:

Value:

Input file:

Filter data

jq '.[]  \
|  select(.age == 30)' largefile.json

Sample Output:

{
  "name": "John Doe",
  "age": 30,
  "city": "New York",
  "hobbies": [
    "reading",
    "swimming",
    "cycling"
  ],
  "address": {
    "street": "123 Main St",
    "zip": "10001"
  }
}

Preview the First Few Entries

If the JSON is an array or a list of objects, you can view the first few entries:

Number of entries:

Input file:

Preview first few entries

jq '.[0:2]' largefile.json

Sample Output:

[
  {
    "name": "John Doe",
    "age": 30,
    "city": "New York",
    "hobbies": [
      "reading",
      "swimming",
      "cycling"
    ],
    "address": {
      "street": "123 Main St",
      "zip": "10001"
    }
  },
  {
    "name": "Jane Smith",
    "age": 28,
    "city": "Los Angeles",
    "hobbies": [
      "painting",
      "yoga",
      "traveling"
    ],
    "address": {
      "street": "456 Oak Ave",
      "zip": "90001"
    }
  }
]

These interactive examples demonstrate various ways to use the jq command for JSON processing. You can adjust the parameters to explore different scenarios on your JSON data.