Squashing commits in Git - Step-by-Step Execution

Process Flow - Squashing commits

Start: Multiple commits

↓

Run git rebase -i HEAD~N

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Editor opens with commit list

↓

Mark commits as 'squash' or 'fixup'

↓

Save and close editor

↓

Git combines commits

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Edit combined commit message

↓

Save and close editor

↓

Rebase completes with squashed commit

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Result: Single combined commit

Squashing combines multiple commits into one by interactive rebasing and editing commit messages.

Execution Sample

Git

git rebase -i HEAD~3
# In editor, mark second and third commits as 'squash'
# Save and close editor
# Edit combined commit message
# Save and close editor

This sequence squashes the last 3 commits into one commit with a combined message.

Process Table

Step	Action	Git State	User Input	Result
1	Run 'git rebase -i HEAD~3'	Last 3 commits separate	None	Editor opens with 3 commits listed
2	Mark commits to squash	Editor shows commits	Mark 2nd and 3rd commits as 'squash'	Commits marked for squashing
3	Save and close editor	Git starts rebasing	None	Git combines the commits into 1
4	Edit combined commit message	Rebase paused for message edit	Write combined commit message	Commit message updated
5	Save and close editor	Rebase continues	None	Rebase completes with 1 squashed commit
6	Check git log	One combined commit replaces 3	None	History shows single squashed commit

💡 Rebase completes successfully with commits squashed into one.

Status Tracker

Variable	Start	After Step 3	After Step 5	Final
Commit count	3	1 (after squash)	1	1
Commit messages	"A", "B", "C"	"A + B + C combined"	"A + B + C combined"	"A + B + C combined"

Key Moments - 3 Insights

Why do we need to mark commits as 'squash' in the editor?

Marking commits as 'squash' tells Git which commits to combine. Without this, Git won't know which commits to merge. See execution_table step 2.

What happens if you don't edit the combined commit message?

Git will use the default combined message from all commits. Editing lets you write a clear, single message. See execution_table step 4.

Why does the rebase pause after combining commits?

It pauses to let you edit the new commit message before finishing. This ensures the final commit message is meaningful. See execution_table step 4.

Visual Quiz - 3 Questions

Look at the execution table, at which step does Git combine the commits?

A Step 3

B Step 2

C Step 5

D Step 1

💡 Hint

Check the 'Result' column in step 3 where commits are combined.

According to the variable tracker, how many commits remain after step 5?

A 3

B 1

C 2

D 0

💡 Hint

Look at 'Commit count' after step 5 in variable_tracker.

If you forget to mark commits as 'squash' in the editor, what happens?

A Git will combine all commits anyway

B Git will abort the rebase

C Git will leave commits separate

D Git will delete commits

💡 Hint

Refer to execution_table step 2 where marking commits is required.

Concept Snapshot

git rebase -i HEAD~N
# Opens editor with last N commits
# Mark commits as 'squash' or 'fixup' to combine
# Save and close editor to start rebase
# Edit combined commit message
# Save and close to finish
Result: Multiple commits become one with combined message

Full Transcript

Squashing commits means combining several commits into one. You start by running 'git rebase -i HEAD~N' where N is how many commits back you want to combine. Git opens an editor listing those commits. You mark the commits you want to squash by changing 'pick' to 'squash' or 'fixup'. After saving and closing the editor, Git combines those commits into one. It then pauses so you can edit the new combined commit message. After saving that, the rebase finishes. The commit history now shows one single commit instead of many. This helps keep history clean and easier to understand.

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