JQ not parsing desired output, can't fetch numbers with string

Question

My json will look like.

{
  "cgi_json_version": "1.8.0",

  "status": {

    "hostgroup_summary": [

      { "hostgroup_name": "ESXI",
        "hosts_up": 9, "hosts_down": 0,
        "hosts_down_unacknowledged": 0, "hosts_down_scheduled": 0,
        "hosts_down_acknowledged": 0, "hosts_down_disabled": 0,
        "hosts_unreachable": 0, "hosts_unreachable_unacknowledged": 0,
        "hosts_unreachable_scheduled": 0, "hosts_unreachable_acknowledged": 0,
        "hosts_unreachable_disabled": 0, "hosts_pending": 0,
        "services_ok": 0, "services_warning": 0,
        "services_warning_unacknowledged": 0, "services_warning_host_problem": 0,
        "services_warning_scheduled": 0, "services_warning_acknowledged": 0,
        "services_warning_disabled": 0, "services_unknown": 0,
        "services_unknown_unacknowledged": 0,
        "services_unknown_host_problem": 0, "services_unknown_scheduled": 0,
        "services_unknown_acknowledged": 0, "services_unknown_disabled": 0,
        "services_critical": 0, "services_critical_unacknowledged": 0,
        "services_critical_host_problem": 0, "services_critical_scheduled": 0,
        "services_critical_acknowledged": 0, "services_critical_disabled": 0,
        "services_pending": 0 
      }

    ]

  }

}

I want to fetch just hosts_up : 9 or simply the number 9, tried many examples but it didn't went well, help me.

Answer 1

As @mklement0 pointed out, you could just write:

$ jq '.status.hostgroup_summary[].hosts_up' input.json
9

Please note, however, that the .keyname trick only works if the key name is alphanumeric and has a leading alphabetic character (it being understood that _ counts as an alphabetic character here). In general, the form .["KEY"] is more robust. Thus, one of the many other alternatives would be:

jq '.["status"]["hostgroup_summary"][] | .["hosts_up"]'

To emit an object, you can use the { "KEY" } abbreviation:

$ jq '.status.hostgroup_summary[] | { "hosts_up" }' input.json
{
  "hosts_up": 9
}

If you want an approach that is completely agnostic about the exact location (or locations) of the "hosts_up" key, consider:

$ jq '.. | .hosts_up? | select(.)'

This will fetch all truthy values associated with a "hosts_up" key, if there are any. (Truthy here means neither null nor false.) If you want to fetch all values associated with the given key, you'd have to check for the key's presence:

$ jq '.. | select(type == "object" and has("hosts_up")) | .hosts_up'

With recent versions of jq, this last can be shortened to:

$ jq '.. | objects | select(has("hosts_up")) | .hosts_up'

Answer 2

With your sample input, extracting the value of interest is straightforward, using the appropriately constructed path to the key of interest:

$ jq '.status.hostgroup_summary[0].hosts_up' file
9

Subkey hostgroup_summary of top-level key status is an array, hence the need to use [0] to target the first element.

A value of any JSON type can be retrieved this way, whether it is a number or not, and technically the output is always a string, though jq by default preserves the JSON value formatting (unquoted output of numbers and Booleans, double-quoted output otherwise; arrays as in JSON).
For scalar values, you can add option -r (raw output) to omit the double quotes.

---

If the array contained multiple entries and you want to extract them all, simply use [] instead of [0]:

$ jq '.status.hostgroup_summary[].hosts_up' file
9

Note with only a single array element the results are the same, but if you had multiple ones, each value would print on a separate line.

---

To return the entry/ies as a whole, as JSON strings containing the key as well, use the following, as also demonstrated in peak's answer:

$ jq '.status.hostgroup_summary[] | { "hosts_up" }' file
{
  "hosts_up": 9
}

---

On a side note: If your path contains keys that do not start with an ASCII letter, digit, or _, you must double-quote them; e.g.

$ jq '.status."0key"' <<<'{ "status": { "0key": 9 } }' # Note the "..." around 0key
9

Answer 3

| jq -r '.[] | .[] | .[] | .hosts_up'  

Above guys.. your downvotes encouraged me to google more and more to find the answer for it and hopefully i found the exact answer for it.

Reference - Using jq to fetch key value from json output

I'm a system admin and i can't show all my hit and trial things all along here.. hope you gonna understand !