Practical jq Guide for Shell Scripts: Parsing and Creating JSON in Bash

A developer building a Linux system health monitor daemon called sykd needed to process JSON data in shell scripts and turned to jq, a lightweight command-line JSON processor. While researching the tool, they found jq's official documentation lengthy and difficult to navigate, prompting them to write a condensed practical guide. The guide covers jq installation across platforms, key command-line options such as -r, -n, and --argjson, and common filter operations including field extraction, array iteration, and conditional logic. It also explains how to pass Bash arrays into jq by first converting them to JSON using printf and jq -R combined with jq -s. The guide recommends testing filters interactively before embedding them in scripts and storing complex logic in separate .jq files for maintainability.