git diff for working directory changes - Mini Project: Build & Apply

Using git diff to See Working Directory Changes

📖 Scenario: You are working on a project using Git for version control. You want to check what changes you have made in your files before committing them.

🎯 Goal: Learn how to use the git diff command to see the changes in your working directory compared to the staging area.

📋 What You'll Learn

Have a Git repository initialized

Have at least one file tracked by Git

Make some changes to a tracked file

💡 Why This Matters

🌍 Real World

Checking changes before committing helps avoid mistakes and keeps your project history clean.

💼 Career

Understanding <code>git diff</code> is essential for developers and DevOps engineers to review code changes effectively.

1

Create a file and add initial content

Create a file called notes.txt with the exact content: Hello World.

Git

# Create a file called notes.txt with the content 'Hello World'
# Your code here

Hint

You can use the echo command to write text to a file.

2

Add the file to Git tracking

Run the command git add notes.txt to start tracking the file in Git.

Git

echo "Hello World" > notes.txt
# Add notes.txt to Git tracking
# Your code here

Hint

Use git add followed by the file name to stage the file.

3

Modify the file content

Change the content of notes.txt to exactly: Hello Git.

Git

echo "Hello World" > notes.txt
git add notes.txt
# Change content of notes.txt to 'Hello Git'
# Your code here

Hint

Use echo again to overwrite the file content.

4

Use git diff to see changes

Run the command git diff to display the changes made in notes.txt compared to the last staged version.

Git

echo "Hello World" > notes.txt
git add notes.txt
echo "Hello Git" > notes.txt
# Run git diff to see changes
# Your code here

Hint

The output will show lines removed with a - and lines added with a +.

Practice

1. What does the command git diff show you?

easy

A. The current branch name

B. The changes in your working directory that are not yet staged

C. The list of all commits in the repository

D. The status of remote branches

Solution

1. Step 1: Understand the purpose of git diff

   git diff compares your working directory files with the last saved snapshot (commit or staged changes).

2. Step 2: Identify what git diff outputs

   It shows the differences that are not yet staged for commit, meaning changes you made but haven't told git to save yet.

3. Final Answer:

   The changes in your working directory that are not yet staged -> Option B

4. Quick Check:

   git diff = unstaged changes [OK]

Hint: git diff shows unstaged file changes only [OK]

Common Mistakes:

• Confusing git diff with git status
• Thinking git diff shows committed changes
• Assuming git diff shows staged changes

2. Which of the following is the correct syntax to see changes only in a single file named app.js?

easy

A. git diff --single app.js

B. git diff --file app.js

C. git diff -f app.js

D. git diff app.js

Solution

1. Step 1: Recall the basic git diff syntax

   The command to check changes in a specific file is git diff <filename>.

2. Step 2: Match the correct option

   Only git diff app.js uses the correct syntax: git diff app.js. Other options use invalid flags.

3. Final Answer:

   git diff app.js -> Option D

4. Quick Check:

   git diff + filename = correct syntax [OK]

Hint: Use git diff followed by filename to check one file [OK]

Common Mistakes:

• Adding unsupported flags like --file or --single
• Using -f which is not for git diff
• Confusing git diff syntax with other git commands

3. Given the following scenario: You modified a file index.html by adding a new line. What will git diff index.html show?

medium

A. The difference showing the added line in index.html

B. An error saying file not found

C. No output because changes are staged

D. The full content of index.html

Solution

1. Step 1: Understand what git diff shows for a modified file

   When a file is changed but not staged, git diff filename shows the exact changes line by line.

2. Step 2: Apply this to index.html

   Since you added a line and did not stage it, the command will show the added line as a difference.

3. Final Answer:

   The difference showing the added line in index.html -> Option A

4. Quick Check:

   git diff filename = shows unstaged changes [OK]

Hint: git diff filename shows unstaged changes in that file [OK]

Common Mistakes:

• Expecting full file content instead of diff
• Thinking git diff shows staged changes
• Assuming error if file exists

4. You ran git diff but saw no output, even though you edited files. What could be the reason?

medium

A. You have untracked files only

B. You are on a detached HEAD state

C. You already staged the changes with git add

D. You have no git repository initialized

Solution

1. Step 1: Understand what git diff shows

   git diff shows changes in the working directory that are not staged.

2. Step 2: Analyze why no output appears despite edits

   If changes are already staged using git add, git diff will show nothing because working directory matches the staging area.

3. Final Answer:

   You already staged the changes with git add -> Option C

4. Quick Check:

   Staged changes hide from git diff output [OK]

Hint: No git diff output? Check if changes are staged [OK]

Common Mistakes:

• Thinking git diff shows staged changes
• Assuming untracked files appear in git diff
• Confusing detached HEAD with diff output

5. You want to review all your unstaged changes in the project but exclude changes in the docs/ folder. Which command will help you achieve this?

hard

A. git diff -- . ':!docs/'

B. git diff --exclude=docs/

C. git diff --ignore docs/

D. git diff --skip docs/

Solution

1. Step 1: Understand how to exclude paths in git diff

   Git supports pathspecs with negation using :!path syntax to exclude files or folders.

2. Step 2: Apply exclusion to docs/ folder

   The correct command uses git diff -- . ':!docs/' to show all changes except those in docs/.

3. Final Answer:

   git diff -- . ':!docs/' -> Option A

4. Quick Check:

   Use pathspec negation ':!folder/' to exclude [OK]

Hint: Use git diff with ':!folder/' to exclude paths [OK]

Common Mistakes:

• Using unsupported flags like --exclude or --ignore
• Trying --skip which is invalid
• Not using pathspec syntax for exclusion