How to Undo a Commit in Git?

In Git, the ability to undo changes is invaluable for maintaining a clean and functional commit history. Whether you need to correct a recent commit, remove changes entirely, or roll back to a previous point, Git offers several ways to undo commits. Knowing the right commands and when to use each method can save time and ensure a smoother development workflow.

In this post, we’ll explore different approaches to undoing a commit in Git, covering the most common scenarios and best practices for each.

Why You Might Want to Undo a Commit

There are several reasons why you might need to undo a commit:

1. Correct a Mistake: Perhaps the commit message was inaccurate, or you need to make additional changes to the code.
2. Revert Changes: In some cases, you might want to remove specific changes entirely from the project.
3. Clean Up Commit History: For a more organized commit history, you might need to amend or squash multiple commits.

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Prerequisites

Before making any changes, it’s essential to understand the difference between committed, staged, and untracked changes in Git. Also, keep in mind that some methods affect only the local repository, while others also impact remote branches.

• Local Commits: These changes are in your local branch and can be edited without affecting the remote repository.
• Remote Commits: Once a commit has been pushed to a shared repository, undoing or editing it may require force-pushing, which affects other collaborators.

Warning: Force-pushing to a shared branch can overwrite others’ work, so use caution when working with remote commits.

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Methods to Undo a Commit in Git

Git provides multiple options to undo a commit, depending on your specific needs. Let’s go through each option.

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1. Undo the Last Commit and Keep Changes Locally (git reset --soft)

If you’ve committed changes but haven’t pushed them yet and want to edit or amend those changes, use git reset --soft.

git reset --soft HEAD~1

• What It Does: This command undoes the last commit but keeps the changes in the staging area, allowing you to make edits or re-commit.
• When to Use: Use git reset --soft if you want to modify the most recent commit without losing any code changes.

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2. Undo the Last Commit and Remove Changes from Staging (git reset --mixed)

If you need to undo a commit and move changes back to your working directory (unstaged), use git reset --mixed.

git reset --mixed HEAD~1

• What It Does: This command undoes the commit and un-stages the changes, moving them back to your working directory.
• When to Use: Use git reset --mixed if you want to remove changes from the last commit without deleting them entirely.

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3. Undo the Last Commit and Discard Changes Completely (git reset --hard)

If you want to remove the commit and discard all changes permanently, use git reset --hard.

git reset --hard HEAD~1

• What It Does: This command undoes the last commit and completely removes all changes, so they can’t be recovered.
• When to Use: Use git reset --hard if you want to revert to the previous state entirely and remove unwanted changes.

Warning: This is a destructive action and should only be used if you’re sure you don’t need the discarded changes.

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4. Revert a Commit in the Middle of History (git revert)

If you want to undo a specific commit without changing the entire history, git revert is an ideal choice. This command creates a new commit that undoes the changes from a specific commit.

git revert <commit-hash>

• What It Does: git revert generates a new commit that undoes the specified commit. Unlike git reset, it doesn’t delete the original commit from history.
• When to Use: Use git revert if the commit has already been pushed to the remote repository or if you need a non-destructive way to undo a commit.

Example:

git revert 123abc

This command undoes the changes introduced by the commit with the hash 123abc and creates a new commit.

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5. Amending the Last Commit (git commit --amend)

If you just need to change the commit message or add additional changes to the last commit, you can use git commit --amend.

git commit --amend

• What It Does: This command opens your default text editor, allowing you to modify the commit message or add changes staged since the last commit.
• When to Use: Use git commit --amend if you want to correct mistakes in the most recent commit or include additional changes without creating a new commit.

Example:

If you forgot to add a file before your last commit:

1. Stage the missing file:

   git add missing-file.txt

2. Amend the previous commit:

   git commit --amend

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6. Undoing Multiple Commits (git reset with Multiple Commits)

If you need to undo several recent commits, you can use git reset with a specific commit hash or a number of commits back.

git reset --hard <commit-hash>

or

git reset HEAD~<number>

• What It Does: This command will remove all commits back to the specified hash or a specified number of commits.
• When to Use: Use this command if you want to go back to a specific point in history, removing multiple recent commits.

Example:

To go back three commits and keep all changes unstaged:

git reset --mixed HEAD~3

To go back to a specific commit hash and remove all changes since that commit:

git reset --hard <commit-hash>

Note: Only use --hard if you are certain that you want to discard all changes since that commit.

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7. Undoing a Pushed Commit (Advanced)

If you’ve already pushed a commit to the remote repository, you can still undo it, but this requires force-pushing, which can affect other collaborators.

Steps:

1. Undo the commit locally using git reset:

   git reset --hard HEAD~1

2. Force-push to the remote repository:

   git push origin <branch-name> --force

• When to Use: Use this with caution, as it overwrites the commit history on the remote branch.

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Summary of Commands

Command	Description	Use Case
git reset --soft HEAD~1	Undo the last commit, keep changes staged	Modify last commit without losing changes
git reset --mixed HEAD~1	Undo last commit, move changes to working directory	Remove commit but keep changes locally
git reset --hard HEAD~1	Undo last commit, remove changes permanently	Completely discard last commit and changes
git revert <commit-hash>	Create a new commit that undoes a specific commit	Undo a commit in a non-destructive way
git commit --amend	Amend the last commit with new changes or message	Add changes or edit commit message
git reset HEAD~<number>	Undo multiple commits, moving to a previous state	Revert to a specific commit in history

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Conclusion

Undoing commits in Git is a crucial skill for managing project history and maintaining clean, accurate commits. By choosing the right method, you can modify, delete, or revert changes efficiently. Whether you’re working on a local branch or need to correct something on a remote branch, these commands offer the flexibility to manage your code and undo mistakes as needed. Remember, always use force-push with caution on shared branches to avoid disrupting your collaborators’ work.