`jq` - command-line JSON processor

jq [-r] [-c] [-n] [-s] [-e] [--arg NAME VALUE] 'FILTER' [file]

Options you will use

-r, --raw-output: Strings come out without quotes - required before you pipe into anything else.
-c, --compact-output: One line per result.
-s, --slurp: Read the whole input into one array.
-n, --null-input: Do not read input; useful with --arg.
-e, --exit-status: Exit 1 if the last output was false or null. For if-tests.
--arg NAME VALUE: Pass a shell value in as $NAME, safely.
.a.b / .[] / .[]?: Field access, array iteration, tolerant iteration.
select(COND) / map(F): Filter, and apply to every element.
@tsv @csv @json: Format an array as TSV, CSV or a JSON string.
--argjson NAME JSON: Set $NAME to a JSON value (a number, true, an object) - unlike --arg, which always makes a string.
--arg NAME VALUE: Set $NAME to the string VALUE inside the filter.

$ jq '.items | length' pods.json

how many

$ jq -r '.items[] | select(.status.phase != "Running") | .metadata.name' pods.json

the unhappy pods

$ jq -r '.items[] | [.metadata.namespace, .metadata.name] | @tsv' pods.json

two fields as TSV

$ jq -r '.. | .image? // empty' pods.json | sort -u

every image anywhere in the document

Try jq in a real terminal Free, in your browser - a real Ubuntu terminal to try it in, with missions that check your work.