jq - Technological watch

Problematic

Working with JSON files often brings challenges in locating and manipulating specific information. Most modern Linux systems come equipped with three renowned text processing utilities: sed, awk, grep.

Before we look into the specifics of jq, it is essential to understand the challenges one faces when dealing with JSON data without a specialized tool:

1. Limited Human Readability: JSON data can be complex and challenging to read, making it hard to discern its structure and content with the naked eye.

2. Inefficient Manual Parsing: Parsing JSON data manually can be time-consuming and prone to errors.

3. Limited Transformation Capabilities: Altering or transforming JSON data without a tool like jq often involves writing custom scripts or code, which can be an unnecessary overhead for simple data manipulation tasks.

About the jq tool

jq is a lightweight, flexible, and powerful command-line tool designed for parsing, querying, and transforming JSON data. It provides a concise and expressive way to filter and manipulate JSON, making it an indispensable tool for anyone working with JSON on a regular basis.

Installation

Installing jq is straightforward and varies depending on your operating system. Here are the installation instructions for popular platforms:

1. Linux (Debian/Ubuntu):

sudo apt-get install jq

2. Linux (Fedora/RHEL):

sudo yum install jq

3. macOS (via Homebrew):

brew install jq

Key jq Commands

Now that you have jq installed, let’s explore some key commands that will help you tackle common JSON data manipulation tasks:

1. Basic JSON Parsing:

jq '.' file.json

or

echo '[{"name":"Alexandre","age":24},{"name":"Hugo","age":25},{"name":"Vincent","age":23}]' | jq '.'

# Output

# [
#    { "name": "Alexandre", "age": 24 },
#    { "name": "Hugo", "age": 25 },
#    { "name": "Vincent", "age": 23 }
# ]

This command will pretty-print the JSON file, making it more human-readable. Replace ’.’ with specific selectors to extract only the data you need.

2. Filtering JSON Objects:

jq '.key' file.json

Replace .key with the specific key you want to extract from the JSON data.

3. Iterating over Arrays:

jq '.array[]' file.json

Use this command to extract all elements from a JSON array.

4. Complex Queries:

jq '.items[] | select(.price < 20)' file.json

This example filters items with a price less than 20 from a JSON array.

5. Modifying JSON Data:

jq '.key = "new_value"' file.json

This command can be used to update the value of a specific key.

More information

• 🔄 “jq” is a powerful tool for working with JSON data, enabling you to query, transform, and process JSON in a more efficient and user-friendly way.

• ⚡ With simple installation steps and key commands at your disposal, you can harness the full potential of “jq” to enhance your data manipulation capabilities.

• 🎯🚀 Whether you are a developer, data analyst, or system administrator, “jq” is a valuable addition to your toolkit, simplifying JSON data processing and making your work more productive and less error-prone.

More informations here:

• Official website: https://jqlang.github.io/jq/
• Manual: https://jqlang.github.io/jq/manual/
• Small guide to use jq: https://www.baeldung.com/linux/jq-command-json