How to Reset or Revert a File to a Specific Revision in Git?

In Git, there are times when you may need to reset or revert a file to a specific revision. This can be useful when you want to undo changes to a particular file without affecting the rest of your project. Here’s how you can achieve this using various Git commands.

Understanding the Basics

Before diving into the steps, it's essential to understand the difference between "reset" and "revert" in the context of Git:

• Reset: Changes the state of your working directory and staging area to match a particular commit. It can be used to undo changes in a more permanent way.
• Revert: Creates a new commit that undoes the changes from a previous commit. This is a safer option when collaborating with others, as it doesn't rewrite history.

Steps to Reset or Revert a File to a Specific Revision

Identify the Commit Hash

First, you need to identify the commit hash (SHA) of the specific revision you want to reset or revert the file to. You can find this using the git log command. This command shows the commit history for the specified file. Note the hash of the commit you want to revert to.

git log -- path/to/file

Resetting a File to a Specific Revision

If you want to reset the file to a specific revision, you can use the git checkout command. This will update the file in your working directory to match the specified commit.

git checkout <commit-hash> -- path/to/file

Replace <commit-hash> with the hash of the commit you noted earlier and path/to/file with the path to your file. For example:

git checkout a1b2c3d4 -- src/app.js

Staging the Reset File

After resetting the file, you need to stage it using git add:

git add path/to/file

Committing the Changes

Finally, commit the changes to your local repository:

git commit -m "Revert file to specific revision"

Reverting a File to a Specific Revision Without Modifying History

If you prefer to revert the changes without modifying the commit history, you can use the git revert command. This command creates a new commit that undoes the changes introduced by a previous commit.

To revert a specific file, follow these steps:

• Identify the Commit Hash: As previously mentioned, use git log to find the commit hash.
• Revert the Specific File: Use git checkout to bring the file to the state of the specific commit.

git checkout a1b2c3d4 -- src/app.js

Commit the Reversion

After checking out the file, stage and commit it as a new commit. This does not change the history but introduces a new commit that undoes the changes.

git add src/app.js
git commit -m "Revert src/app.js to state in commit a1b2c3d4"

Force Push (If Necessary)

If you need to push these changes to a remote repository and your branch is protected or shared, you might need to force push. Use this with caution

git push --force origin branch-name

Conclusion

Resetting or reverting a file to a specific revision in Git involves checking out the file from a particular commit, staging it, and committing the change. This process allows you to undo changes to a specific file without affecting the rest of your project. Use git reset for a more permanent solution and git revert to create a new commit that undoes changes, preserving the history. Always ensure you understand the implications of force pushing changes to shared branches.