Pretty-Printing JSON in Shell Scripts: A Developer’s Guide

Working with JSON data is common in software development, especially in web development where it is often used for configuration files, communication between servers, and more. While JSON’s data structure is easy to understand, it can become quite difficult to read when it is compacted into a single line. This is where pretty-printing comes into play, enhancing the readability of JSON data by formatting it with proper indentations and line breaks.

Why Pretty-Print JSON?

Pretty-printing JSON transforms it from a compact one-liner like this:

{"foo": "lorem", "bar": "ipsum"}

into a more readable format:

{
  "foo": "lorem",
  "bar": "ipsum"
}

This formatting makes it easier to read and understand the structure of the data, especially when dealing with large JSON files.

Tools for Pretty-Printing JSON in Shell

There are several tools available that can be used directly within your shell environment to pretty-print JSON. Here’s how you can use some of the most popular ones:

1. Python’s JSON Module:

   Python’s built-in JSON module can be used to pretty-print JSON. If you have Python installed, you can pipe JSON data through Python’s JSON tool:

   echo '{"foo": "lorem", "bar": "ipsum"}' | python -m json.tool
   

   This method is beneficial because Python is commonly installed on many systems, and it doesn’t require any additional installations.

2. jq:

   jq is a powerful and flexible command-line JSON processor. It can pretty-print JSON and perform complex manipulations. To use jq for pretty-printing:

   echo '{"foo": "lorem", "bar": "ipsum"}' | jq .
   

   jq is particularly useful for more advanced JSON processing tasks beyond just pretty-printing.

3. Node.js JSON Tool:

   If you have Node.js installed, you can use a simple command to pretty-print JSON:

   echo '{"foo": "lorem", "bar": "ipsum"}' | npx json
   

   This command uses npx which is part of the Node.js package ecosystem, making it easy to execute Node packages without installing them.

Installing jq and Node.js JSON Tool

If you find these tools appropriate for your needs but don’t have them installed, you can easily install them as follows:

• jq:

  sudo apt-get install jq  # For Debian/Ubuntu
  brew install jq          # For macOS
  

• Node.js:

  curl -sL https://deb.nodesource.com/setup_14.x | sudo -E bash -
  sudo apt-get install -y nodejs
  

  After installing Node.js, npx will be available to run Node packages.

Pretty-printing JSON in shell scripts can greatly improve the readability of JSON data, making it easier to debug and maintain your code. Whether you choose Python, jq, or Node.js tools depends on your specific needs and the complexity of the JSON data you are dealing with. Each tool offers unique advantages, from simple formatting to powerful data manipulation.