Squashing commits in Git - Mini Project: Build & Apply

Squashing Commits in Git

📖 Scenario: You are working on a small project and have made several commits. Now, you want to clean up your commit history by combining these commits into one before sharing your work with your team.

🎯 Goal: Learn how to squash multiple commits into a single commit using Git interactive rebase.

📋 What You'll Learn

Create a Git repository with three commits

Set a variable for the number of commits to squash

Use Git interactive rebase to squash commits

Show the final commit log with a single combined commit

💡 Why This Matters

🌍 Real World

Squashing commits helps keep the project history clean and easier to understand before sharing code with others.

💼 Career

Many software development teams require clean commit histories for code reviews and collaboration, making this skill essential for developers.

1

Create a Git repository with three commits

Initialize a new Git repository called myproject. Create three commits with these exact commit messages in order: First commit, Second commit, and Third commit. Use the commands git init, git add, and git commit -m as needed.

Git

# Initialize repository and create three commits with exact messages
# Your code here

Hint

Use git init to start the repo. Then create or modify a file and commit three times with the exact messages.

2

Set the number of commits to squash

Create a shell variable called NUM_COMMITS and set it to 3 to represent the number of commits you want to squash.

Git

mkdir myproject
cd myproject
git init
echo "Line 1" > file.txt
git add file.txt
git commit -m "First commit"
echo "Line 2" >> file.txt
git add file.txt
git commit -m "Second commit"
echo "Line 3" >> file.txt
git add file.txt
git commit -m "Third commit"
# Set NUM_COMMITS to 3
# Your code here

Hint

Use NUM_COMMITS=3 to set the variable.

3

Use Git interactive rebase to squash commits

Run the command git rebase -i HEAD~$NUM_COMMITS to start an interactive rebase for the last three commits. In the editor that opens, change the second and third commits from pick to squash to combine them into the first commit. Save and close the editor to complete the squash.

Git

mkdir myproject
cd myproject
git init
echo "Line 1" > file.txt
git add file.txt
git commit -m "First commit"
echo "Line 2" >> file.txt
git add file.txt
git commit -m "Second commit"
echo "Line 3" >> file.txt
git add file.txt
git commit -m "Third commit"
NUM_COMMITS=3
# Run interactive rebase and squash commits
# Your code here

Hint

Use git rebase -i HEAD~$NUM_COMMITS and then edit the commit list to squash.

4

Show the final commit log with a single combined commit

Run git log --oneline to display the commit history. The output should show only one commit with a combined message from the three original commits.

Git

mkdir myproject
cd myproject
git init
echo "Line 1" > file.txt
git add file.txt
git commit -m "First commit"
echo "Line 2" >> file.txt
git add file.txt
git commit -m "Second commit"
echo "Line 3" >> file.txt
git add file.txt
git commit -m "Third commit"
NUM_COMMITS=3
git rebase -i HEAD~$NUM_COMMITS
# In the editor, change second and third 'pick' to 'squash' and save
# Now show the commit log
# Your code here

Hint

Use git log --oneline to see the combined commit message.

Practice

1. What is the main purpose of squashing commits in Git?

easy

A. To revert the last commit without changing history

B. To combine multiple commits into one for a cleaner history

C. To create a new branch from the current commit

D. To delete all commits from the repository

Solution

1. Step 1: Understand commit history management

   Squashing is used to combine several commits into a single commit to simplify the commit history.

2. Step 2: Identify the purpose of squashing

   This helps keep the project history clean and easier to read by reducing clutter from many small commits.

3. Final Answer:

   To combine multiple commits into one for a cleaner history -> Option B

4. Quick Check:

   Squashing = combine commits [OK]

Hint: Squash = combine commits to clean history [OK]

Common Mistakes:

• Thinking squashing deletes commits permanently
• Confusing squashing with branching
• Believing squashing reverts commits

2. Which Git command starts an interactive rebase to squash commits?

easy

A. git commit --squash HEAD~3

B. git merge -i HEAD~3

C. git rebase -i HEAD~3

D. git reset --soft HEAD~3

Solution

1. Step 1: Identify the command for interactive rebase

   The command to start an interactive rebase is git rebase -i followed by the commit range.

2. Step 2: Confirm the correct syntax

   git rebase -i HEAD~3 opens the last 3 commits for editing, allowing squashing.

3. Final Answer:

   git rebase -i HEAD~3 -> Option C

4. Quick Check:

   Interactive rebase = git rebase -i [OK]

Hint: Use git rebase -i to start squashing commits [OK]

Common Mistakes:

• Using git merge -i which does not exist
• Trying git commit --squash which is invalid
• Confusing reset with rebase for squashing

3. Given these commits:

commit1: Add README
commit2: Fix typo
commit3: Update README formatting

If you run git rebase -i HEAD~3 and squash commit2 and commit3 into commit1, what will the commit history show?

medium

A. One commit combining messages from commit1, commit2, and commit3

B. Three separate commits unchanged

C. One commit with message from commit1 only

D. Two commits: commit1 and combined commit2+commit3

Solution

1. Step 1: Understand squash behavior in interactive rebase

   Squashing merges commits into one, combining their changes and commit messages.

2. Step 2: Result of squashing commit2 and commit3 into commit1

   The final commit will include all changes and combined commit messages from all three commits.

3. Final Answer:

   One commit combining messages from commit1, commit2, and commit3 -> Option A

4. Quick Check:

   Squash merges commits and messages [OK]

Hint: Squash merges commits and their messages together [OK]

Common Mistakes:

• Assuming only the first commit message remains
• Expecting commits to stay separate after squash
• Thinking squash deletes commit messages

4. You ran git rebase -i HEAD~4 to squash commits but got a conflict error. What should you do next?

medium

A. Manually fix the conflicts, then run git rebase --continue

B. Abort the rebase with git rebase --abort and try again

C. Run git reset --hard to discard all changes

D. Push your changes immediately to remote to fix conflicts

Solution

1. Step 1: Understand conflict during rebase

   A conflict means Git needs you to fix code differences manually before continuing.

2. Step 2: Resolve conflicts and continue rebase

   Fix the conflicts in files, then run git rebase --continue to proceed with squashing.

3. Final Answer:

   Manually fix the conflicts, then run git rebase --continue -> Option A

4. Quick Check:

   Fix conflicts + git rebase --continue [OK]

Hint: Fix conflicts manually then git rebase --continue [OK]

Common Mistakes:

• Aborting rebase without trying to fix conflicts
• Using git reset --hard which discards work
• Pushing incomplete changes to remote

5. You squashed commits locally and want to update the remote branch. What is the correct command to push your changes safely?

hard

A. git push --all origin

B. git push origin main

C. git push --no-verify origin main

D. git push --force-with-lease origin main

Solution

1. Step 1: Understand effect of squashing on commit history

   Squashing rewrites commit history, so the remote branch history differs from local.

2. Step 2: Use force push safely

   To update remote with rewritten history, use git push --force-with-lease to avoid overwriting others' work accidentally.

3. Final Answer:

   git push --force-with-lease origin main -> Option D

4. Quick Check:

   Force push safely after squash [OK]

Hint: Use git push --force-with-lease after squash [OK]

Common Mistakes:

• Using normal git push causing rejection
• Using --no-verify which skips hooks but not force push
• Pushing all branches unnecessarily