Скачать или смотреть How to Create a Hardlink and Mimic File Content Using C Programming

A detailed guide on creating a hardlink in C programming, specifically addressing the challenge of mimicking file content. Learn the step-by-step solution to ensure your hardlinks function as expected.
---
This video is based on the question https://stackoverflow.com/q/76161180/ asked by the user 'Xposed' ( https://stackoverflow.com/u/19799559/ ) and on the answer https://stackoverflow.com/a/76162013/ provided by the user 'Allan Wind' ( https://stackoverflow.com/u/9706/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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: How to create a hardlink

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Create a Hardlink and Mimic File Content Using C Programming

When working with files in C programming, you may encounter situations where you wish to create hardlinks between two files. One common use case is when you want one file to mimic the content of another file. In this guide, we will address a specific challenge related to hardlinking and provide a clear solution to ensure your hardlinks work correctly.

The Problem: Creating a Hardlink

Imagine you are developing a program that requires two files: e.txt and void.txt. The goal is for void.txt to mimic the content of e.txt. However, during implementation, you find that writing data to void.txt does not reflect in e.txt, as you expected. This can be frustrating, especially when you’re trying to achieve file synchronization through hardlinks.

Understanding Hardlinks

Before diving into the solution, let’s quickly recap what a hardlink is. A hardlink is a directory entry that associates a name with a file on a filesystem. It's important to note:

Both files share the same data on the disk.

Changes made in one file are reflected in the other because they point to the same data blocks.

The Original Code Overview

Here’s a snippet of the original C code causing confusion:

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

As you can see, the program attempts to create a hardlink from e.txt to void.txt, but it's the other way around that we desire.

The Solution: Swap the Arguments

To fix this issue, you need to swap the order of the arguments in the link function call within the traplink function. The correct version should look like this:

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

This modification tells the program to link void.txt to e.txt, allowing the latter to mimic any changes made to the former.

Final Code Example

Here’s how the modified code looks with the necessary changes implemented:

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

Validating the Results

After implementing the code, you can run a command in the terminal to verify that both files share the same inode number:

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

This command will display the inode numbers of e.txt and void.txt, confirming they are now linked correctly.

Conclusion

In summary, creating a hardlink to make one file mimic another in C requires careful attention to the order of arguments in the link function. By ensuring that the source file (the one that you want to reflect changes) is specified first, you achieve the desired file synchronization. Happy coding!