How to undo a Git commit?

Undoing a Git Commit

In the world of Git, the ability to undo a commit is a powerful feature that can help you rectify mistakes and maintain a clean commit history. Whether you've made a commit with the wrong message, forgotten to include a file, or simply want to revert a change, Git provides several options to undo your commit.

Soft Reset

The most gentle way to undo a commit is to use the git reset command with the --soft option. This command will move the branch pointer back to the specified commit, but it will leave the changes in your working directory and staging area. This is useful if you want to make additional changes before re-committing.

# Undo the last commit
git reset --soft HEAD~1

# Undo the 3rd last commit
git reset --soft HEAD~3

Here's a Mermaid diagram to visualize the git reset --soft operation:

graph LR A[Commit 1] --> B[Commit 2] --> C[Commit 3] --> D[Commit 4] D --"git reset --soft HEAD~1"--> B

Hard Reset

If you want to completely discard the changes in your working directory and staging area, you can use the git reset command with the --hard option. This will move the branch pointer back to the specified commit and discard all local changes.

# Undo the last commit and discard all changes
git reset --hard HEAD~1

# Undo the 3rd last commit and discard all changes
git reset --hard HEAD~3

Here's a Mermaid diagram to visualize the git reset --hard operation:

graph LR A[Commit 1] --> B[Commit 2] --> C[Commit 3] --> D[Commit 4] D --"git reset --hard HEAD~1"--> B

Amend the Last Commit

If you've made a commit and want to modify it, you can use the git commit --amend command. This will allow you to change the commit message, add or remove files, or make other changes to the last commit.

# Amend the last commit
git commit --amend

This will open your default text editor, where you can modify the commit message or make other changes. Once you save and exit the editor, the last commit will be updated with your changes.

Revert a Commit

If you want to undo the changes introduced by a specific commit, you can use the git revert command. This will create a new commit that undoes the changes from the specified commit, preserving the commit history.

# Revert the last commit
git revert HEAD

# Revert the 3rd last commit
git revert HEAD~2

Here's a Mermaid diagram to visualize the git revert operation:

graph LR A[Commit 1] --> B[Commit 2] --> C[Commit 3] --> D[Commit 4] D --"git revert HEAD"--> E[Revert Commit]

In summary, Git provides several options to undo a commit, each with its own use case and trade-offs. The git reset --soft command is useful for making additional changes before re-committing, while git reset --hard is for discarding all local changes. git commit --amend allows you to modify the last commit, and git revert creates a new commit that undoes the changes from a specific commit. By understanding these commands, you can effectively manage your Git history and correct any mistakes or unwanted changes.