git revert to undo a commit safely - Mini Project: Build & Apply

Undo a Commit Safely Using git revert

📖 Scenario: You are working on a project and accidentally committed a change that you want to undo without losing the history of your work.

🎯 Goal: Learn how to safely undo a commit using git revert so that the commit history remains intact and the unwanted changes are undone.

📋 What You'll Learn

Create a git repository with an initial commit

Make a second commit with a change

Use git revert to undo the second commit

Show the commit log to confirm the revert

💡 Why This Matters

🌍 Real World

In real projects, mistakes happen. Using <code>git revert</code> helps undo changes without losing history, which is important for teamwork and tracking.

💼 Career

Knowing how to safely undo commits is a key skill for developers and DevOps engineers to maintain clean and reliable project histories.

1

Initialize a Git repository and create the first commit

Run the commands to initialize a git repository, create a file named file.txt with the content Hello World, add it to git, and commit with the message Initial commit.

Git

# Your code here

Hint

Use git init to start the repository. Use echo to create the file. Then add and commit.

2

Make a second commit with a change

Modify file.txt by adding the line This is a second line, then add and commit the change with the message Added second line.

Git

git init
echo "Hello World" > file.txt
git add file.txt
git commit -m "Initial commit"
# Your code here

Hint

Use >> to append text to the file. Then add and commit the change.

3

Undo the second commit safely using git revert

Use git revert with the commit hash of the second commit to create a new commit that undoes the changes from the second commit.

Git

git init
echo "Hello World" > file.txt
git add file.txt
git commit -m "Initial commit"
echo "This is a second line" >> file.txt
git add file.txt
git commit -m "Added second line"
# Your code here

Hint

Use git revert HEAD to undo the last commit safely.

4

Show the commit log to confirm the revert

Run git log --oneline to display the commit history and confirm that the revert commit is present.

Git

git init
echo "Hello World" > file.txt
git add file.txt
git commit -m "Initial commit"
echo "This is a second line" >> file.txt
git add file.txt
git commit -m "Added second line"
git revert HEAD
# Your code here

Hint

The output should show three commits including the revert commit.

Practice

1. What does the git revert command do in a Git repository?

easy

A. It merges two branches together.

B. It deletes the commit from the project history permanently.

C. It resets the branch to a previous commit without creating a new commit.

D. It creates a new commit that undoes the changes of a previous commit.

Solution

1. Step 1: Understand the purpose of git revert

   git revert creates a new commit that reverses the changes made by a specified previous commit.

2. Step 2: Compare with other commands

   Unlike git reset, it does not remove commits from history but safely adds a new commit to undo changes.

3. Final Answer:

   It creates a new commit that undoes the changes of a previous commit -> Option D

4. Quick Check:

   git revert = new commit undoing changes [OK]

Hint: Remember: revert adds a new commit to undo changes [OK]

Common Mistakes:

• Confusing revert with reset which removes commits
• Thinking revert deletes commits permanently
• Assuming revert merges branches

2. Which of the following is the correct syntax to revert the latest commit in Git?

easy

A. git revert HEAD

B. git revert --latest

C. git revert -m HEAD

D. git revert --undo HEAD

Solution

1. Step 1: Identify the correct command to revert the latest commit

   The latest commit is referenced by HEAD, and the correct command is git revert HEAD.

2. Step 2: Check invalid options

   Options like --latest, -m without context, or --undo are not valid revert flags.

3. Final Answer:

   git revert HEAD -> Option A

4. Quick Check:

   Revert latest commit = git revert HEAD [OK]

Hint: Use HEAD to revert the latest commit safely [OK]

Common Mistakes:

• Using invalid flags like --latest or --undo
• Confusing revert options with reset options
• Trying to revert without specifying a commit

3. Given the following Git commands executed in order:

git commit -m "Add feature A"
git commit -m "Fix bug B"
git revert HEAD

What will be the result of the last command?

medium

A. The commit "Fix bug B" is deleted from history.

B. The branch is reset to the commit "Add feature A" without a new commit.

C. A new commit is created that undoes the changes from "Fix bug B".

D. An error occurs because HEAD cannot be reverted.

Solution

1. Step 1: Identify the commit pointed by HEAD

   After two commits, HEAD points to "Fix bug B" commit.

2. Step 2: Understand what git revert HEAD does

   It creates a new commit that reverses the changes introduced by the latest commit "Fix bug B".

3. Final Answer:

   A new commit is created that undoes the changes from "Fix bug B" -> Option C

4. Quick Check:

   git revert HEAD = new commit undoing latest commit [OK]

Hint: Revert HEAD always creates a new undo commit [OK]

Common Mistakes:

• Thinking revert deletes commits from history
• Confusing revert with reset which moves HEAD
• Assuming revert causes errors on HEAD

4. You ran git revert abc123 but got a merge conflict error. What should you do to fix this?

medium

A. Run git revert --abort to cancel the revert and try again.

B. Manually resolve the conflicts, then run git revert --continue.

C. Delete the commit abc123 and try reverting again.

D. Use git reset --hard to fix the conflict.

Solution

1. Step 1: Understand merge conflicts during revert

   Revert can cause conflicts if changes overlap. You must resolve conflicts manually.

2. Step 2: Continue revert after resolving conflicts

   After fixing conflicts, run git revert --continue to complete the revert commit.

3. Final Answer:

   Manually resolve the conflicts, then run git revert --continue -> Option B

4. Quick Check:

   Resolve conflicts + git revert --continue = fix revert conflict [OK]

Hint: Fix conflicts, then run git revert --continue [OK]

Common Mistakes:

• Trying to delete commits to fix revert conflicts
• Using git reset which discards changes unsafely
• Aborting revert without resolving conflicts

5. You want to undo a commit that was pushed and shared with your team, but keep the project history intact. Which approach is safest?

hard

A. Use git revert <commit-hash> to create a new commit that undoes the changes.

B. Use git reset --hard <commit-hash> and force push to rewrite history.

C. Delete the commit from the remote repository manually.

D. Use git checkout <commit-hash> to switch to the previous commit.

Solution

1. Step 1: Consider shared repository safety

   When commits are shared, rewriting history (reset + force push) can cause problems for others.

2. Step 2: Use revert to safely undo changes

   git revert adds a new commit that reverses changes without rewriting history, keeping the project safe and intact.

3. Final Answer:

   Use git revert <commit-hash> to create a new commit that undoes the changes -> Option A

4. Quick Check:

   Revert = safe undo for shared commits [OK]

Hint: Revert to undo shared commits safely, never reset [OK]

Common Mistakes:

• Using reset and force push on shared branches
• Deleting commits manually from remote
• Checking out old commits without reverting