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

To reset a file to a specific revision in Git, use git checkout <commit_hash> -- <file_path> to retrieve the file from a specific commit without changing your branch. Alternatively, you can use git restore <file_path> --source=<commit_hash> in newer Git versions, or create a revert commit with git revert <commit_hash> if you want to undo changes while maintaining history.

Contents

• How to Reset a Single File to a Specific Commit
• How to Create a Revert Commit
• Alternative Approaches for File Recovery
• Best Practices and Considerations
• Common Problems and Solutions

How to Reset a Single File to a Specific Commit

Using git checkout

The traditional way to reset a single file to its state at a specific commit is using git checkout:

git checkout <commit_hash> -- <file_path>

For example, if you want to reset a file named README.md to its state in commit a1b2c3d4, you would run:

git checkout a1b2c3d4 -- README.md

This command takes the version of README.md from commit a1b2c3d4 and places it in your working directory and staging area. The -- is important to prevent ambiguity between file paths and branch names.

Note: This command will overwrite the current version of the file in your working directory without creating a new commit. The change will be staged (added to the index) but not yet committed.

Using git restore

In newer versions of Git (2.23+), the git restore command provides a more intuitive way to restore files:

git restore --source=<commit_hash> <file_path>

For example:

git restore --source=a1b2c3d4 README.md

This achieves the same result as the git checkout method but with clearer syntax. The --source option specifies which commit to take the file from.

Both methods will reset the file to the state it was in at the specified commit, but they won’t affect your branch pointer - only the specific file will be changed.

How to Create a Revert Commit

If you want to undo changes made to a file in a specific commit and preserve this change in history (rather than just locally resetting the file), you should create a revert commit:

Step-by-step revert process

1. First, identify the commit hash that contains the changes you want to undo:

   bash

   git log --oneline -- <file_path>
   

2. Create a revert commit that undoes those changes:

   bash

   git revert <commit_hash>
   

3. Git will open an editor with a commit message. You can edit it or save as-is.

4. Commit the revert:

   bash

   :wq  # In vim, or your editor's equivalent
   

This creates a new commit that reverses the changes made in the specified commit, making your history reflect that the changes were applied and then undone.

Handling merge conflicts

If the revert causes conflicts (because changes were made on top of the commit you’re reverting), Git will pause and allow you to resolve them:

1. Resolve conflicts in the affected files
2. Stage the resolved files:
   bash

   git add <resolved_file>
   

3. Continue the revert process:
   bash

   git revert --continue
   

If you want to abort the revert process due to conflicts:

git revert --abort

Alternative Approaches for File Recovery

Using git show for direct content viewing

If you want to see what a file looked like in a specific commit without immediately changing your working file:

git show <commit_hash>:<file_path>

This will display the contents of the file at that commit to your terminal. You can redirect this output to a file:

git show <commit_hash>:<file_path> > new_file_name.txt

Saving changes before resetting

Before resetting a file that you’ve modified, it’s wise to save your current changes in case you need them later:

# Create a branch with your current changes
git branch save-my-changes

# Or stash your changes
git stash push -m "Message describing changes"

# Then reset the file
git checkout <commit_hash> -- <file_path>

# Later, you can restore your changes:
git checkout save-my-changes  # If you created a branch
# Or
git stash pop  # If you used stash

Best Practices and Considerations

Preserving vs. modifying history

• Use git checkout or git restore when you want to locally reset a file without affecting shared history
• Use git revert when working with shared repositories to maintain a clean, linear history that others can pull
• Avoid git reset --hard for individual files when working with shared repositories, as it can rewrite history

Working with shared repositories

When working on branches that others might be using:

• Always prefer git revert over git reset to avoid rewriting shared history
• Communicate with your team before making significant reverts
• Consider creating a feature branch for experimenting with reverts

Common Problems and Solutions

Resolving conflicts after reset

If you encounter conflicts after resetting a file:

1. The conflicted file will have markers like <<<<<<<, =======, and >>>>>>>
2. Edit the file to resolve the conflicts manually
3. Stage the resolved file:
   bash

   git add <file_path>
   

4. Complete the operation:
   bash

   git rebase --continue  # If during a rebase
   # Or just commit if it was a direct reset
   

Recovering from accidental resets

If you accidentally reset a file and lost changes:

1. Check your reflog to find recent commands:
   bash

   git reflog
   

2. Look for the commit where your file was still modified
3. Restore the file from that commit:
   bash

   git checkout <reflog_entry_hash> -- <file_path>
   

Conclusion

• Resetting a file to a specific revision in Git can be done with git checkout <commit> -- <file> or the newer git restore --source=<commit> <file>
• For undoing changes in a way that preserves history, use git revert <commit> to create a new commit that reverses the changes
• Always consider whether you’re working on a personal branch or shared repository when choosing between reset and revert
• Use git show to examine a file’s content at a specific commit without immediately changing your working file
• Save your current changes before resetting using branches or stashing to prevent accidental data loss
• Check your reflog if you need to recover from accidental resets

With these techniques, you can effectively manage file revisions in Git while maintaining a clean and understandable project history.