git merge command - Mini Project: Build & Apply

Using the git merge Command

📖 Scenario: You are working on a project with two branches: main and feature. You want to combine the changes from the feature branch into the main branch to update the main project with new features.

🎯 Goal: Learn how to use the git merge command to combine changes from one branch into another safely and correctly.

📋 What You'll Learn

Create a new branch called feature from main

Make a commit on the feature branch

Switch back to the main branch

Merge the feature branch into main using git merge

💡 Why This Matters

🌍 Real World

Merging branches is a daily task in software development to combine new features or fixes into the main project code.

💼 Career

Understanding how to merge branches correctly is essential for collaboration in teams and managing code changes safely.

1

Create the feature branch and make a commit

Create a new branch called feature from main using git branch feature. Then switch to the feature branch using git checkout feature. Finally, create a new file called feature.txt with the content New feature added and commit it with the message Added feature.txt.

Git

# Create the feature branch and switch to it
# Create feature.txt with content 'New feature added'
# Commit the new file with message 'Added feature.txt'

Hint

Use git branch to create the branch, git checkout to switch, then create and commit the file.

2

Switch back to the main branch

Switch back to the main branch using git checkout main.

Git

git branch feature
git checkout feature
echo "New feature added" > feature.txt
git add feature.txt
git commit -m "Added feature.txt"
# Switch back to main branch below

Hint

Use git checkout main to switch back to the main branch.

3

Merge the feature branch into main

Use the git merge feature command to merge the changes from the feature branch into the main branch.

Git

git branch feature
git checkout feature
echo "New feature added" > feature.txt
git add feature.txt
git commit -m "Added feature.txt"
git checkout main
# Merge feature branch into main below

Hint

Run git merge feature while on the main branch to combine changes.

4

Verify the merge result

Run git log --oneline and cat feature.txt to verify that the feature.txt file from the feature branch is now in the main branch.

Git

git branch feature
git checkout feature
echo "New feature added" > feature.txt
git add feature.txt
git commit -m "Added feature.txt"
git checkout main
git merge feature
# Verify the merge by showing git log and content of feature.txt

Hint

Use git log --oneline to see commits and cat feature.txt to see the file content.

Practice

1. What does the git merge command do in Git?

easy

A. It combines changes from one branch into the current branch.

B. It deletes a branch permanently.

C. It creates a new branch from the current branch.

D. It shows the commit history of the current branch.

Solution

1. Step 1: Understand the purpose of git merge

   The git merge command is used to combine changes from one branch into another branch.

2. Step 2: Identify the correct description

   Among the options, only It combines changes from one branch into the current branch. correctly describes merging changes into the current branch.

3. Final Answer:

   It combines changes from one branch into the current branch. -> Option A

4. Quick Check:

   git merge = combine branches [OK]

Hint: Merge means combine changes into current branch [OK]

Common Mistakes:

• Confusing merge with branch deletion
• Thinking merge creates a new branch
• Mixing merge with viewing history

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

easy

A. git merge --create feature

B. git merge -b feature

C. git merge feature

D. git merge --delete feature

Solution

1. Step 1: Recall the basic merge syntax

   The correct syntax to merge a branch is git merge branch_name.

2. Step 2: Match the syntax with options

   git merge feature matches the correct syntax. Options B, C, and D use invalid flags or commands.

3. Final Answer:

   git merge feature -> Option C

4. Quick Check:

   git merge + branch name = correct syntax [OK]

Hint: Use 'git merge branch_name' to merge branches [OK]

Common Mistakes:

• Adding incorrect flags like -b or --create
• Confusing merge with branch creation or deletion
• Using merge without specifying branch name

3. Given the following commands run in order:

git checkout main
git merge feature

What happens if the feature branch has commits not in main?

medium

A. The main branch is reset to feature branch state.

B. The feature branch is deleted automatically.

C. Git throws an error and stops the merge.

D. The commits from feature are added to main.

Solution

1. Step 1: Understand merge behavior with new commits

   When merging a branch with new commits, Git combines those commits into the current branch.

2. Step 2: Analyze the options

   The commits from feature are added to main correctly describes this behavior. Options B, C, and D describe incorrect or unrelated behaviors.

3. Final Answer:

   The commits from feature are added to main. -> Option D

4. Quick Check:

   Merge adds commits [OK]

Hint: Merge adds commits, does not delete branches [OK]

Common Mistakes:

• Thinking merge deletes branches
• Expecting merge to reset branches
• Assuming merge always fails with new commits

4. You run git merge feature but Git reports a conflict. What should you do next?

medium

A. Restart Git to clear the conflict.

B. Manually resolve the conflicts in files, then run git add and git commit.

C. Run git merge --force to ignore conflicts.

D. Delete the feature branch and try merging again.

Solution

1. Step 1: Understand merge conflicts

   When Git reports conflicts, it means changes clash and need manual fixing.

2. Step 2: Resolve conflicts properly

   You must edit conflicted files to fix issues, then stage and commit the changes to complete the merge.

3. Final Answer:

   Manually resolve the conflicts in files, then run git add and git commit. -> Option B

4. Quick Check:

   Fix conflicts manually, then add and commit [OK]

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

Common Mistakes:

• Trying to force merge ignoring conflicts
• Deleting branches to fix conflicts
• Restarting Git expecting conflicts to clear

5. You want to merge branch feature into main but keep main's changes in case of conflict (favor main). Which command helps achieve this?

hard

A. git merge -X ours feature

B. git merge --no-ff feature

C. git merge -s recursive feature

D. git merge --abort feature

Solution

1. Step 1: Understand merge strategies

   The -X ours option tells Git to favor the current branch's changes during conflicts.

2. Step 2: Match the option to the goal

   git merge -X ours feature uses -X ours to keep main's changes if conflicts occur. Other options do not achieve this.

3. Final Answer:

   git merge -X ours feature -> Option A

4. Quick Check:

   Use -X ours to favor current branch on conflicts [OK]

Hint: Use 'git merge -X ours' to keep current branch changes [OK]

Common Mistakes:

• Confusing -X ours with --no-ff
• Using --abort to fix conflicts
• Not specifying strategy option