How to Update a JSON File Using jq in Bash Scripts

Learn how to effectively change values in JSON files using the `jq` command in Bash scripts, and troubleshoot common errors.
---

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: JSON file update using jq (bash script)

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Updating a JSON File Using jq in Bash Scripts

Working with JSON files is a common task in many programming and scripting scenarios. Whether you're developing applications or managing system configurations, you'll often find yourself needing to modify JSON data. In this guide, we’ll tackle a practical problem of updating a value in a JSON file using the jq command in a Bash script. We'll dive into understanding how jq functions, and we'll troubleshoot a specific error that can arise during this process.

Understanding the Problem

[[See Video to Reveal this Text or Code Snippet]]

You want to change the value of the "Period" tag from "Daily" to "Weekly". However, when you execute the command:

[[See Video to Reveal this Text or Code Snippet]]

You encounter the following error:

[[See Video to Reveal this Text or Code Snippet]]

This error occurs because the map() function is not suited for use on the JSON object you are dealing with. Let's break down the solution to correctly update the value.

The Solution: Correct Command Structure

The key to resolving this issue lies in understanding how jq works with JSON objects and arrays. Here’s how to effectively update the value in your JSON file:

Correct jq Command

Instead of trying to use map() directly on the main object (which treats the JSON object as a dictionary), you should target the Tags array specifically. The correct command is:

[[See Video to Reveal this Text or Code Snippet]]

Explanation of the Command

.Tags: This is how you access the Tags array specifically within your JSON object.

|=: This operator modifies the Tags array in place.

map(...): This function iterates over each element (each tag) in the Tags array.

if .Key == "Period": This condition checks if the key of the current tag is "Period".

.Value = "Weekly": If the condition is true, it updates the Value to "Weekly".

else . end: If the condition is not met, it leaves the tag unchanged.

Final Summary

With the correct command, you will be able to update the specific tag value with ease. Always remember that when working with jq on JSON files, it’s crucial to understand the structure of your JSON and to use the right functions to navigate through it effectively.

You can run the command in your terminal as follows:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

Using jq to manipulate JSON values in a Bash script can be highly effective once you understand how to use it correctly. Next time you encounter an operation that involves modifying JSON data, remember this structured approach to avoid common pitfalls. Happy coding!