How can I revert a single file to a previous version in Git and Github?

In the dynamic world of software development, collaboration is key. As developers, we often find ourselves working on shared repositories, making changes, and testing features. In this process, there might be instances where we need to revert a specific file to a particular commit. This action is crucial, especially when we've made changes to files unrelated to our pull request for testing purposes. Instead of manually reverting each line of code and creating a new commit, which can clutter our commit history, there's a more streamlined approach: reverting the file. Let's delve into the step-by-step process.

Identifying the Commit ID

To begin, navigate to the shared repository on GitHub and locate the file you wish to revert. Above the file content, you'll notice a unique 7-digit commit ID along with a date. This ID represents the latest commit where the file underwent modifications. It's essential to either note down this commit ID or copy it for future use.

Determining the File Path

Next, we need the file's path relative to the working directory. Conveniently, this path is displayed on the same GitHub page where you found the commit ID. It's crucial to remember that the first directory mentioned is the working directory. Hence, ensure you only consider the path after the working directory name.

Executing the Revert

With the commit ID and file path in hand, it's time to revert the file. Open your terminal, navigate to the working directory, and use the git checkout command. The command structure is as follows:

git checkout [commit ID] -- path/to/file

For instance, if you're reverting a file named example.js with a commit ID of a1b2c3d, the command would be:

git checkout a1b2c3d -- path/to/example.js

Committing the Reverted File

While our primary goal is to revert the file without creating unnecessary commits, once the file is reverted, it's imperative to commit this change. This ensures that our local branch and the version on GitHub are synchronized. Use the standard commit command:

git commit -m 'Reverted file to [commit ID]'

Then, push the commit to the remote repository.

Advanced Scenarios: Handling Complex Reverts

In the realm of software development, not all situations are straightforward. There might be instances where a file has undergone multiple changes, or you might need to revert multiple files simultaneously. Let's explore some advanced scenarios and how to handle them.

Reverting Multiple Files

If you find yourself in a situation where multiple files need to be reverted to their respective commits, the process remains largely the same. However, you'll be executing the git checkout command multiple times, once for each file:

git checkout [commit ID 1] -- path/to/file1
git checkout [commit ID 2] -- path/to/file2
...

After reverting all the necessary files, commit the changes collectively:

Reverting to a Previous Commit

In some cases, you might want to revert the entire repository to a previous commit. This can be achieved using the git reset command:

git reset --hard [commit ID]

This command will revert the entire repository to the specified commit ID, discarding all changes made after that commit.

Handling Merge Conflicts

Reverting files can sometimes lead to merge conflicts, especially if the file has been modified by multiple collaborators. In such cases, Git will notify you of the conflict. You'll need to manually resolve the conflict by choosing which changes to keep and which to discard. Once resolved, commit the changes:

git commit -m 'Resolved merge conflicts after revert'

Key Takeaways

To efficiently revert a single file:

1. Identify the desired file's commit ID.
2. Determine the file's path from the working directory.
3. Use the git checkout command to revert the file.
4. Commit the reverted file to maintain repository consistency.

References

• Official Git Documentation
• GitHub Help - Reverting a commit