jqlisted

# jq - JSON Querying and Transformation ## Overview `jq` is the standard CLI tool for querying and reshaping JSON. This skill covers practical, expert-level usage: filtering deeply nested data, transforming structures, aggregating values, and composing `jq` into shell pipelines. Every example is copy-paste ready for real workflows. ## Workflow 1. Read the input. Identify the JSON source - pasted text, a file, or a piped command (`curl`, `kubectl`, `aws`, `gh`, `docker`). 2. Inspect the shape. Run `jq 'keys'` or `jq '.[0]'` on a sample to confirm actual field names and nesting before writing the filter. 3. Build the filter incrementally. Start from the root, add one pipe stage at a time, verifying each stage against the sample. 4. Choose output mode. Use `-r` for shell consumption, `-c` for NDJSON pipelines, default pretty-print for human reading. 5. Verify against sample input before embedding in a script. Confirm no `null`/empty surprises. 6. Deliver the final command plus a one-line explanation of each filter stage (see Output Format). ## How It Works `jq` takes a filter expression and applies it to JSON input. Filters compose with pipes (`|`), and `jq` handles arrays, objects, strings, numbers, booleans, and `null` natively. ### Basic Selection ```bash # Extract a field echo '{"name":"alice","age":30}' | jq '.name' # "alice" # Nested access echo '{"user":{"email":"a@b.com"}}' | jq '.user.email' # Array index echo '[10, 20, 30]' | jq '.[1]' # 20 # Array slice ech