Example of (basic) jq query

bookstore.json

[{
  "store": {
    "books": [
      {
        "category": "reference",
        "author": "Nigel Rees",
        "title": "Sayings of the Century",
        "price": 8.95
      },
      {
        "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Sword of Honour",
        "price": 12.99
      },
      {
        "category": "fiction",
        "author": "Herman Melville",
        "title": "Omoo",
        "isbn": "978-1169307773",
        "price": 40.14
      },
      {
        "category": "fiction",
        "author": "Herman Melville",
        "title": "Moby Dick",
        "isbn": "0-553-21311-3",
        "price": 8.99
      },
      {
        "category": "fiction",
        "author": "J. R. R. Tolkien",
        "title": "The Lord of the Rings",
        "isbn": "0-395-19395-8",
        "price": 22.99
      },
      {
        "category": "fiction",
        "author": "Evelyn Waugh",
        "title": "Brideshead Revisited",
        "price": 14.99
      }
    ]
  }
}]

(basic) Querying with jq

With an input as file bookstore.json, we can easily do some basic query

How many books there are, over 8$ and under 12$ ?

jq '[.[].store.books[] | select(.price >= 8 and .price < 12)] | length' your_file.json

>>> 2

How many books have been written by each author?

jq '.[].store.books | group_by(.author)[]  | {author: .[0].author, length: length} ' your_file.json

and output will be

  {
    "author": "Evelyn Waugh",
    "length": 2
  },
  {
    "author": "Herman Melville",
    "length": 2
  },
  {
    "author": "J. R. R. Tolkien",
    "length": 1
  },
  {
    "author": "Nigel Rees",
    "length": 1
  }