Git Revert and Reset
Understand how to revert (undo) changes made in commits using 'git revert'. Learn the different types of reset (soft, mixed, hard) and their effects using 'git reset'.
Git Reset vs. Git Revert: When to Use Which
Understanding the difference between git reset and git revert is crucial for managing your Git repository effectively. Both commands allow you to undo changes, but they do so in fundamentally different ways, impacting your commit history and collaboration with others.
Git Reset Explained
git reset moves the current branch's HEAD to a specified commit. This effectively rewrites the history by discarding commits. It has three main modes:
--soft: Moves the HEAD to the specified commit, but leaves the staging area and working directory untouched. Changes are staged for commit.--mixed: (Default) Moves the HEAD to the specified commit and unstages the changes. The changes remain in the working directory.--hard: Moves the HEAD to the specified commit and discards all changes in the staging area and working directory. Use with extreme caution, as this can lead to data loss.
Example:
git reset --hard HEAD~2 # Moves HEAD back two commits, discarding them and all their changes.Git Revert Explained
git revert creates a new commit that undoes the changes made by a specific commit. This doesn't rewrite the history; instead, it adds a new commit to the history that effectively cancels out the changes from the reverted commit.
Example:
git revert HEAD # Creates a new commit that undoes the changes of the last commit.
git revert <commit-hash> # Reverts the changes from the specified commit by its hash.Git Reset vs. Git Revert: Key Differences
| Feature | Git Reset | Git Revert |
|---|---|---|
| History | Rewrites history (can discard commits). | Preserves history (creates a new commit to undo changes). |
| Impact on remote branches | Can cause issues when pushing to remote branches, especially if others have based work on the commits you're discarding. Requires a force push git push --force, which is generally discouraged on shared branches. | Safe to push to remote branches as it doesn't rewrite history. |
| Working directory/staging area | Can modify the working directory and staging area depending on the mode (--soft, --mixed, --hard). | Does not directly modify the working directory or staging area (creates a new commit). |
| Complexity | Potentially simpler for undoing local changes that haven't been pushed. | Generally safer and more complex, but provides a clearer audit trail. |
| Data Loss | Can lead to data loss, especially with --hard. | Less prone to data loss, as the original commits are still in the history. |
When to Use Which: A Comparative Analysis
Choosing between git reset and git revert depends on several factors, including:
- Whether the changes have been pushed to a shared repository: If the changes have been pushed,
git revertis almost always the better choice. Rewriting shared history withgit resetcan cause significant problems for other collaborators. - Whether you want to preserve the history: If you want to maintain a complete audit trail of all changes, including the undoing of specific commits, use
git revert. - Whether you're working on a private branch: If you're working on a local branch that hasn't been shared, and you want to clean up the history or discard changes completely,
git resetmight be appropriate. However, still proceed with caution. - The desired outcome: Do you want to completely erase a mistake from the local history and never speak of it again (reset)? Or would you rather say "I made a mistake, and this commit fixes it" (revert)?
Scenarios:
- You made a mistake in your local, unpublished branch and want to completely remove it: You can use
git reset --hard <commit-before-mistake>. Be sure you haven't pushed! - You pushed a commit to a shared branch that introduced a bug: Use
git revert <commit-with-bug>. This creates a new commit that fixes the bug without rewriting history. - You want to undo several commits in your local branch, but want to keep the option of revisiting them later: Use
git reverton each commit you want to undo, in reverse order. - You committed something locally that you didn't mean to commit, and it hasn't been pushed: Consider
git reset --soft HEAD~1to uncommit it. The changes will be staged, ready to be amended, rewritten, or otherwise changed before committing again.
Team Workflow Considerations
The choice between git reset and git revert is also heavily influenced by your team's workflow and Git usage conventions.
- Collaboration: If your team relies heavily on shared branches,
git revertis the safer option to avoid disrupting other developers' work. - Code review:
git revertmakes the intention of undoing a change much clearer during code review, as it's a visible commit in the history. - Training: Ensure all team members understand the difference between
git resetandgit revertand the potential consequences of each command. Establish guidelines for when to use which.
In summary, when in doubt, git revert is often the safer and more collaborative choice, especially when working with shared repositories. Use git reset cautiously and primarily for local, unpublished changes.