Скачать или смотреть How to Save JSON jq Output as Separate Variables or as an Array in Bash

Learn how to effectively use jq to parse JSON data from i3 workspaces in Bash, allowing you to save and access visible workspace names effortlessly.
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Working with JSON jq Output in Bash

If you're using i3 as your window manager and want to manage your workspaces efficiently, you might find it quite useful to parse the output of the command i3-msg -t get_workspaces. This command returns JSON data that describes your workspaces, including which ones are visible. The challenge often lies in how to manipulate and extract specific values from this JSON output, especially if you're new to working with JSON in the bash shell.

In this guide, we'll explore how to extract the names of the visible workspaces and save them as separate variables or in an array using the powerful jq tool. The key focus will be on leveraging jq effectively to filter and read data.



Understanding the JSON Structure

When you run i3-msg -t get_workspaces, you get a JSON output that looks something like this:

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

In this JSON structure, each workspace has attributes like id, num, name, and visible. The goal here is to extract only the name values of workspaces that have visible set to true.

Extracting the Visible Workspace Names

Step 1: Using jq to Filter Data

The essential part of the solution involves using jq to filter the visible workspaces. Here's how you can achieve that with a command:

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

This command will output the names of the visible workspaces, but they will be returned as a quoted JSON array like this:

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

Step 2: Save Output as an Array

To take this a step further and utilize the extracted names, you can read them into a bash array. The most straightforward way to do this is by using the following command:

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

In this case, you're directly creating an array X that holds all the visible workspace names. Now, you can loop through this array easily:

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Output:

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Alternative Method: Utilizing readarray

If your shell supports readarray (or mapfile), you have another method to read lines into an array:

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

More Robust Handling of Input

If you're concerned about spaces or want enhanced handling, you can use the while loop idiom to populate an array:

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

This approach ensures that every line is captured correctly, allowing for greater flexibility.



Conclusion

With these methods, you can effectively work with JSON in bash to manage your i3 workspaces. Extracting visible workspace names and storing them in variables or arrays not only enhances your scripting capabilities but also improves your workflow significantly.

If you encounter any issues or have questions about using jq or parsing JSON in bash, feel free to reach out or share your experiences in the comments below!