How to parse json data using jq?

Question

I need to fetch below objects from json which I am getting via API. I am trying with jq which is available on ubuntu 16.04. I am trying to get data in this format device_name C:| free 18707755008.0 total_size 55832473600.0

Any suggest how should i approach on this ? The goal is get above 3 object in excel.

{
    "logical": {
        "D:|": {
            "device_name": [
                "D:\\"
            ],
            "used_percent": [
                52.6,
                "%"
            ],
            "fstype": "NTFS",
            "free": [
                10178084864.0,
                "B"
            ],
            "total_size": [
                21471686656.0,
                "B"
            ],
            "used": [
                11293601792.0,
                "B"
            ],
            "opts": "rw,fixed"
        },
        "C:|": {
            "device_name": [
                "C:\\"
            ],
            "used_percent": [
                66.5,
                "%"
            ],
            "fstype": "NTFS",
            "free": [
                18707755008.0,
                "B"
            ],
            "total_size": [
                55832473600.0,
                "B"
            ],
            "used": [
                37124718592.0,
                "B"
            ],
            "opts": "rw,fixed"
        }
    }
}

Answer 1

The following outputs 2 lines with a string format seen on the last line you can easily change:

jq -M -r '.[] | keys[] as $var |
 [.[$var].free[0], .[$var].total_size[0]] as [$f,$t] |
 "device_name \($var) free \($f) total_size \($t)" '

output:

device_name C:| free 18707755008 total_size 55832473600
device_name D:| free 10178084864 total_size 21471686656

Answer 2

Use this :

jq '.logical["D:|"].free[0], .logical["D:|"].total_size[0]' file.json

Output:

10178084864
21471686656

Answer 3

Assuming that you want the device names from the device_name key's value under logical rather than from the keys directly under logical (this makes it easier and also gives you a value that is a valid device name on Windows systems), and that you also want what I believe is the unit of measurement attached to the actual numbers (would make sense if there is a chance that you might have variable units in the data):

jq -r '
    ["Device name", "Free space", "Total size"],
    (
        .logical[] |
        [
            .device_name[0],
            (.free       | map(tostring) | add),
            (.total_size | map(tostring) | add)
        ]
    ) | @csv' file.json

Given the data in the question in file.json, this would generate the following CSV document (which would be trivial to import into Excel):

"Device name","Free space","Total size"
"D:\","10178084864B","21471686656B"
"C:\","18707755008B","55832473600B"

Change each of the two calls to add into join(" ") if you want to have a space between the number and the unit.