Скачать или смотреть How to Fix Cursor Position in Linux Terminal Using ANSI Escape Codes

Learn how to keep your cursor in place while updating symbols in the Linux terminal with ANSI escape codes.
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This video is based on the question https://stackoverflow.com/q/74337227/ asked by the user 'kancler' ( https://stackoverflow.com/u/18823391/ ) and on the answer https://stackoverflow.com/a/74337621/ provided by the user 'Rachid K.' ( https://stackoverflow.com/u/14393739/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Introduction

Have you ever wanted to update a character in the Linux terminal without moving your cursor to the next column? Whether you're developing interactive applications or simply need a cleaner terminal experience, keeping the cursor fixed can be a game changer. In this post, we'll figure out how to maintain the cursor position using ANSI escape codes.

Understanding the Problem

When you press a key in a terminal, the default behavior is to move the cursor to the next column automatically. While this is useful in many situations, there are instances where you may want to maintain the cursor's column position while updating the symbol. In this guide, we'll look at how to achieve this by using ANSI escape codes effectively.

Key Concepts

Terminal in Raw Mode: This allows your program to receive input directly without any fallback actions from the terminal, letting you control when and how to display characters.

ANSI Escape Codes: These are sequences that control cursor movement, screen formatting, and more, making them essential in customizing your terminal interactions.

The Solution: Using ANSI Escape Codes

To fix the cursor position in the Linux terminal, we need to perform the following steps:

Set the Terminal to Raw Mode: This allows the terminal to take direct input.

Enable Non-Echo Mode: Prevents the terminal from automatically displaying what you type.

Use ANSI Escape Codes: These codes will help manage the cursor movements.

Example Implementation in Shell

Below is a simple shell script that demonstrates this concept:

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

Key Parts of the Code

CSI Variable: This holds the ANSI escape sequence, which is used throughout the script for cursor manipulation.

trap restore EXIT: This ensures that if the script exits, the terminal settings are restored to normal mode.

stty Command: Used to set the terminal modes to raw and non-echo.

While Loop: Continuously reads single characters and reacts according to the input:

If it reads an empty character (like space), it moves the cursor forward.

If it reads a "Q", the loop exits.

Any other character updates the screen at the same position.

Implementing the Same in C

The concept remains the same in C. You can use similar ANSI escape codes and functions to handle input and control cursor movements. Make sure to call fflush(stdout) after printf() calls for immediate output to the terminal.

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

Conclusion

By utilizing ANSI escape codes, you can maintain cursor positions in the Linux terminal effectively while updating characters as needed. This approach is highly beneficial for anyone looking to build more interactive terminal applications.

Now you can enjoy a more controlled terminal experience and focus on what truly matters—your code!