unix command formatting flattening nested json objects data

Have a look at gron. From the linked page:

Make JSON greppable!

gron transforms JSON into discrete assignments to make it easier to grep for what you want and see the absolute 'path' to it. It eases the exploration of APIs that return large blobs of JSON but have terrible documentation.

▶ gron "https://api.github.com/repos/tomnomnom/gron/commits?per_page=1" | fgrep "commit.author"
json[0].commit.author = {};
json[0].commit.author.date = "2016-07-02T10:51:21Z";
json[0].commit.author.email = "[email protected]";
json[0].commit.author.name = "Tom Hudson";

gron can work backwards too, enabling you to turn your filtered data back into JSON:

▶ gron "https://api.github.com/repos/tomnomnom/gron/commits?per_page=1" | fgrep "commit.author" | gron --ungron
[
  {
    "commit": {
      "author": {
        "date": "2016-07-02T10:51:21Z",
        "email": "[email protected]",
        "name": "Tom Hudson"
      }
    }
  }
]

Jq is the right tool for processing JSON data (https://stedolan.github.io/jq/manual/v1.5/).

Sample input.json:

{
  "data": {
    "div1": {
      "name": "some name",
      "age": 1,
      "address_1": "some address",
      "items": {
        "item_x1": "some data"
      }
    },
    "div2": {
      "name": "some other name",
      "age": 2,
      "address_2": "some address",
      "items": {
        "item_x2": "some data"
      }
    },
    "div3": {
      "name": "another name",
      "age": 3,
      "address_3": "some address",
      "items": {
        "item_x3": "some data"
      }
    }
  }
}

jq -c '"data" as $main_k | .data as $data | .data | to_entries
       | group_by(.key) | map(from_entries)[] | [paths(scalars)]
       | map(("\($main_k)." + join(".")) as $key
             | {($key): (reduce .[] as $k ($data; . = .[$k]))})
       | add' input.json

The output:

{"data.div1.name":"some name","data.div1.age":1,"data.div1.address_1":"some address","data.div1.items.item_x1":"some data"}
{"data.div2.name":"some other name","data.div2.age":2,"data.div2.address_2":"some address","data.div2.items.item_x2":"some data"}
{"data.div3.name":"another name","data.div3.age":3,"data.div3.address_3":"some address","data.div3.items.item_x3":"some data"}