jq is a command-line tool for processing and manipulating JSON data. It provides a simple and powerful way to filter and transform JSON structures in shell scripts.

Installation

To use jq, you need to install it on your system. Here is how you can do it on different platforms:

Mac OS X

brew install jq

Debian-based Linux

sudo apt-get install jq

Red Hat-based Linux

sudo yum install jq

Basic Usage

Once you have jq installed, you can use it to perform various operations on JSON data. Here are some common use cases:

1. Filter JSON data

To filter JSON data based on specific conditions, you can use the select() function. For example, let’s say we have a JSON file called data.json with the following content:

[
  {"name": "John", "age": 30},
  {"name": "Jane", "age": 25},
  {"name": "Mike", "age": 35}
]

We can filter the data to only include persons older than 30:

jq '.[] | select(.age > 30)' data.json

This will output:

{"name":"Mike","age":35}

2. Extract specific fields

You can use jq to extract specific fields from JSON data. For example, let’s say we have the same JSON file as above, and we want to extract only the names of the persons:

jq '.[].name' data.json

This will output:

"John"
"Jane"
"Mike"

3. Combine multiple operations

jq '.[] | select(.age > 30) | .name' data.json

This will output:

"Mike"

Conclusion

jq is a versatile tool for processing and manipulating JSON data in shell scripts. It provides a concise and powerful syntax for filtering and transforming JSON structures. With its easy installation and straightforward usage, jq can greatly enhance your shell scripting workflow.

#tech #shellscripting