jq

Created: 2018-11-13 15:45:46 -0800 Modified: 2019-10-14 09:52:43 -0700

Basics (reference)

You can install this for any OS via their GitHub link.
JQ is a JSON parser. It’s like XPATH for JSON.
You can quickly try sample inputs/outputs in their sandbox: https://jqplay.org/
- This is especially helpful because it gives you the command line as output at the bottom.
To strip the resulting quotation marks from the string, use “—raw-output” or “-r” (reference).

Examples

Fetch a sibling value based on the value of a given key (reference)

Goal: figure out the ListenerArn of the object whose port is 8079 (i.e. get “arn_bar”):

{
    "Listeners": [
        {
            "Port": 443,
            "ListenerArn": "arn_foo"
        },
        {
            "Port": 8079,
            "ListenerArn": "arn_bar"
        },
        {
            "Port": 4873,
            "ListenerArn": "arn_baz"
        }
    ]
}

Final query: .Listeners[] | select(.Port == 8079) | .ListenerArn