Merge commit creation in Git - Commands & Configuration

Introduction

When you work on different features or fixes in separate branches, you need to combine them into one. A merge commit is a special commit that joins these branches together, keeping the history clear and showing where the branches merged.

When you finish a feature in a separate branch and want to add it to the main branch.

When you want to combine bug fixes from a hotfix branch back into the main code.

When multiple team members work on different branches and you need to unify their work.

When you want to keep a clear record of when and how branches were combined.

When resolving conflicts between branches before finalizing the combined code.

Commands

Switch to the main branch where you want to merge changes.

Terminal

git checkout main

Expected Output

Switched to branch 'main'

Merge the 'feature-branch' into the current branch, creating a merge commit if needed.

Terminal

git merge feature-branch

Expected Output

Updating 1a2b3c4..5d6e7f8

Fast-forward

 file.txt | 2 ++

 1 file changed, 2 insertions(+)

Show the latest commit with a graph to confirm the merge commit was created.

Terminal

git log --oneline --graph --decorate -1

Expected Output

* 5d6e7f8 (HEAD -> main, feature-branch) Add new feature to file.txt

→

--oneline - Show commits in a short, one-line format

→

--graph - Display commit history as a graph

→

--decorate - Show branch and tag names

Key Concept

If you remember nothing else from this pattern, remember: a merge commit joins two branches and keeps a clear history of their combination.

Common Mistakes

Trying to merge without switching to the target branch first.

Git merges into the current branch, so merging on the wrong branch combines changes where you don't want them.

Always run 'git checkout' to switch to the branch you want to merge into before running 'git merge'.

Using 'git merge' when the branches have no new commits, expecting a merge commit to be created.

Git will do a fast-forward merge without creating a merge commit if possible, so no merge commit appears.

Use 'git merge --no-ff feature-branch' to force a merge commit even if fast-forward is possible.

Summary

Switch to the branch where you want to combine changes using 'git checkout'.

Run 'git merge' with the branch name to join changes and create a merge commit.

Use 'git log --oneline --graph --decorate -1' to verify the merge commit and see the history.

Practice

1. What does a git merge <branch-name> command do in Git?

easy

A. Combines changes from the specified branch into the current branch with a merge commit

B. Deletes the specified branch from the repository

C. Creates a new branch named after the specified branch

D. Resets the current branch to the specified branch's state without merging

Solution

1. Step 1: Understand the purpose of git merge

   The git merge <branch-name> command is used to combine changes from another branch into the current branch.

2. Step 2: Identify the result of the merge

   This operation creates a merge commit that records the integration of changes from both branches.

3. Final Answer:

   Combines changes from the specified branch into the current branch with a merge commit -> Option A

4. Quick Check:

   Merge command = combine branches with commit [OK]

Hint: Merge means combine branches with a commit [OK]

Common Mistakes:

• Confusing merge with branch deletion
• Thinking merge creates a new branch
• Assuming merge resets branch without commit

2. Which of the following is the correct syntax to create a merge commit from branch feature into the current branch?

easy

A. git merge feature

B. git merge -b feature

C. git merge --delete feature

D. git merge --reset feature

Solution

1. Step 1: Recall the basic merge syntax

   The correct syntax to merge a branch is git merge <branch-name> without extra flags for a normal merge commit.

2. Step 2: Evaluate the options

   git merge feature matches the correct syntax. The other options use invalid or unrelated flags.

3. Final Answer:

   git merge feature -> Option A

4. Quick Check:

   Simple merge = git merge branch [OK]

Hint: Use 'git merge branch-name' to merge simply [OK]

Common Mistakes:

• Adding unnecessary flags like -b or --delete
• Confusing merge with branch creation or deletion commands
• Using reset flag which is unrelated to merge

3. Given the following commands executed in order:

git checkout main
git merge feature

What will Git do if there are no conflicts between main and feature and the branches have diverged?

medium

A. Reset main branch to feature branch state without commit

B. Delete the feature branch automatically

C. Create a merge commit combining changes from feature into main

D. Fail with an error asking to resolve conflicts

Solution

1. Step 1: Understand the merge process without conflicts

   If there are no conflicts and the branches have diverged, Git will automatically create a merge commit combining changes from the feature branch into main.

2. Step 2: Confirm no branch deletion or errors occur

   Git does not delete branches or reset branches automatically during merge without conflicts.

3. Final Answer:

   Create a merge commit combining changes from feature into main -> Option C

4. Quick Check:

   No conflicts + diverged = auto merge commit [OK]

Hint: No conflicts + diverged means merge commit created automatically [OK]

Common Mistakes:

• Thinking feature branch is deleted after merge
• Expecting errors when no conflicts exist
• Confusing merge with reset or branch deletion

4. You run git merge feature but Git reports conflicts. What should you do next to complete the merge?

medium

A. Delete the current branch and recreate it to fix conflicts

B. Run git merge --abort to cancel the merge and delete the feature branch

C. Run git reset --hard to force merge without fixing conflicts

D. Manually fix conflicts in files, then run git add and git commit

Solution

1. Step 1: Understand conflict resolution process

   When Git reports conflicts, you must manually fix the conflicting files by editing them.

2. Step 2: Complete the merge after fixing conflicts

   After fixing, stage the changes with git add and finish the merge with git commit.

3. Final Answer:

   Manually fix conflicts in files, then run git add and git commit -> Option D

4. Quick Check:

   Fix conflicts, add, commit to complete merge [OK]

Hint: Fix conflicts manually, then add and commit [OK]

Common Mistakes:

• Aborting merge and deleting branches unnecessarily
• Using reset to skip conflict resolution
• Deleting branches instead of resolving conflicts

5. You want to merge branch feature into main but avoid creating a merge commit. Which command should you use?

hard

A. git merge --no-ff feature

B. git merge --squash feature

C. git merge --ff-only feature

D. git merge --abort feature

Solution

1. Step 1: Understand merge commit creation options

   The --squash option merges changes without creating a merge commit by combining all changes into one commit.

2. Step 2: Compare other options

   --no-ff forces a merge commit, --ff-only only merges if fast-forward is possible, and --abort cancels merges.

3. Final Answer:

   git merge --squash feature -> Option B

4. Quick Check:

   Squash merges without merge commit [OK]

Hint: Use --squash to merge without merge commit [OK]

Common Mistakes:

• Using --no-ff which forces merge commit
• Confusing --ff-only with no commit creation
• Trying to abort merge to avoid commit