git diff --staged for staged changes - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the command git diff --staged show?

It shows the differences between the files in the staging area and the last commit. In other words, it displays what changes are ready to be committed.

beginner

How is git diff --staged different from git diff?

git diff shows changes in your working directory that are not yet staged, while git diff --staged shows changes that have been staged and are ready to commit.

beginner

Can git diff --staged be used to see changes after committing?

No. It only shows staged changes that are not yet committed. After committing, the staging area is cleared, so no staged changes remain.

beginner

What is the purpose of staging changes in Git?

Staging lets you prepare and review changes before committing them. It acts like a 'ready to commit' basket where you collect changes you want to include in the next commit.

beginner

How do you stage a file for commit in Git?

Use git add <filename> to move changes from your working directory to the staging area.

What does git diff --staged compare?

A Last commit vs remote repository

B Unstaged changes vs last commit

C Staged changes vs last commit

D Working directory vs staging area

git diff --staged shows differences between the staged files and the last commit.

Which command shows changes not yet staged?

A git commit

B git diff --staged

C git status

D git diff

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

What must you do before git diff --staged shows any output?

A Make a commit

B Stage changes with <code>git add</code>

C Push to remote

D Create a new branch

You need to stage changes first using git add for git diff --staged to show differences.

If you run git diff --staged and see no output, what does it mean?

A No staged changes

B No commits yet

C No changes in working directory

D Repository is corrupted

No output means there are no changes staged for commit.

Which command stages a file named app.js?

A git add app.js

B git commit app.js

C git diff app.js

D git push app.js

git add app.js stages the file app.js for commit.

Explain what git diff --staged does and when you would use it.

Think about the staging area and what is ready to be saved in Git.

Describe the difference between git diff and git diff --staged.

Consider where the changes are: working directory or staging area.

Practice

1. What does the command git diff --staged show?

easy

A. Changes that are staged and ready to be committed

B. All changes in the working directory, staged or not

C. The commit history of the repository

D. Untracked files in the repository

Solution

1. Step 1: Understand what staging means in Git

   Staging means preparing changes to be saved in the next commit.

2. Step 2: Identify what git diff --staged compares

   This command compares the staged changes against the last commit, showing what will be committed.

3. Final Answer:

   Changes that are staged and ready to be committed -> Option A

4. Quick Check:

   Staged changes = git diff --staged output [OK]

Hint: Remember: --staged shows only prepared changes [OK]

Common Mistakes:

• Confusing staged changes with all changes
• Thinking it shows commit history
• Assuming it lists untracked files

2. Which of the following is the correct syntax to view staged changes using git?

easy

A. git diff staged

B. git diff --cached

C. git diff --stage

D. git diff --status

Solution

1. Step 1: Recall git diff options for staged changes

   Git uses --cached as the official option to show staged changes.

2. Step 2: Understand that --staged is an alias

   --staged is a common alias but --cached is the correct and original syntax.

3. Final Answer:

   git diff --cached -> Option B

4. Quick Check:

   Correct syntax for staged diff = git diff --cached [OK]

Hint: Use --cached to view staged changes reliably [OK]

Common Mistakes:

• Using incorrect flags like --stage
• Omitting the double dash before options
• Confusing staged with unstaged flags

3. Given the following commands executed in order:

echo 'Hello' > file.txt
git add file.txt
git diff --staged

What will git diff --staged display?

medium

A. No output, because the file is new and staged

B. An error because the file is not committed yet

C. The difference showing removal of 'Hello' in file.txt

D. The difference showing the addition of 'Hello' in file.txt

Solution

1. Step 1: Understand the state of file.txt after commands

   The file is new with content 'Hello' and has been staged with git add.

2. Step 2: What does git diff --staged show here?

   It shows the difference between the staged version and the last commit (which has no file.txt), so it shows the addition of 'Hello'.

3. Final Answer:

   The difference showing the addition of 'Hello' in file.txt -> Option D

4. Quick Check:

   New staged file diff shows added content [OK]

Hint: New staged files show additions in git diff --staged [OK]

Common Mistakes:

• Expecting no output for new files
• Thinking git diff --staged errors on new files
• Confusing removal with addition

4. You modified files in your editor, staged them with git add, ran git diff --staged but saw no output. What could be the problem?

medium

A. You staged the files but forgot to save changes in the editor

B. You used git diff instead of git diff --staged

C. You committed the changes already, so no staged changes remain

D. The repository has no commits yet

Solution

1. Step 1: Check if file changes are saved before staging

   If changes are not saved in the editor, staging old content means no visible diff.

2. Step 2: Understand why no output appears

   Since staged content matches last commit (or is empty), git diff --staged shows nothing.

3. Final Answer:

   You staged the files but forgot to save changes in the editor -> Option A

4. Quick Check:

   Unsaved edits cause empty staged diff [OK]

Hint: Always save files before staging to see diffs [OK]

Common Mistakes:

• Assuming git diff --staged shows unstaged changes
• Not realizing files were not saved
• Thinking commit status affects staged diff output

5. You have staged changes in two files: app.js and index.html. You want to see only the staged changes in app.js. Which command should you use?

hard

A. git diff --cached index.html

B. git diff app.js staged

C. git diff --staged app.js

D. git diff --staged --name-only app.js

Solution

1. Step 1: Understand how to limit git diff to a specific file

   You can specify the file path after the options to filter the diff output.

2. Step 2: Choose the correct syntax for staged changes and file filter

   git diff --staged app.js correctly shows staged changes only for app.js.

3. Final Answer:

   git diff --staged app.js -> Option C

4. Quick Check:

   File filter after --staged shows staged diff for that file [OK]

Hint: Put filename after --staged to filter staged diff [OK]

Common Mistakes:

• Placing filename before options
• Using --name-only which lists files, not diffs
• Mixing staged and unstaged file filters