git diff for working directory changes - Step-by-Step Execution

Process Flow - git diff for working directory changes

Make changes in files

↓

Run 'git diff'

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Git compares working directory vs staging area

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Show line-by-line differences

↓

User sees what changed before staging

Shows how git diff compares your current file changes against the staging area to display differences.

Execution Sample

Git

git diff

# Shows changes in working directory not yet staged

This command shows line differences between your current files and the staging area.

Process Table

Step	Action	Comparison	Output
1	Modify file 'app.txt'	Working directory changed	No output yet
2	Run 'git diff'	Compare 'app.txt' in working directory vs staging area	Shows lines removed (-) and added (+)
3	Review output	See what lines changed before staging	Diff output with line numbers and +/- signs
4	No changes left	Working directory matches staging area	No output (empty)

💡 Stops when all changes are reviewed or no differences exist

Status Tracker

Variable	Start	After 1	After 2	Final
app.txt content	Original commit content	Modified content with changes	Same as After 1	Same as After 1

Key Moments - 2 Insights

Why does 'git diff' show nothing after staging changes?

Because 'git diff' compares working directory to the staging area (index), and staging copies changes from working directory to index, so working directory matches staging area content.

What do the '+' and '-' signs mean in the diff output?

'-' means a line was removed from the working directory version, '+' means a line was added in the working directory version, as shown in step 2 of the execution_table.

Visual Quiz - 3 Questions

Look at the execution table, what does step 2 output show?

A Lines added and removed between working directory and staging area

B List of staged files

C Commit history

D Untracked files

💡 Hint

Check the 'Output' column in step 2 of the execution_table

At which step does 'git diff' show no output?

A Step 1

B Step 2

C Step 4

D Step 3

💡 Hint

Look at the 'Output' column for step 4 in the execution_table

If you modify a file but do not run 'git diff', what will the output be?

A Shows line differences

B No output

C Shows staged changes

D Shows commit logs

💡 Hint

Refer to step 1 in the execution_table where changes are made but no command run yet

Concept Snapshot

git diff
- Shows line-by-line changes in working directory vs staging area
- '+' lines added, '-' lines removed
- Useful to review changes before staging
- No output means no differences
- Only compares unstaged changes

Full Transcript

When you change files in your project, git diff helps you see what exactly changed compared to the staging area. You run 'git diff' and git compares your current files to the staging area. It shows lines removed with a minus sign and lines added with a plus sign. This helps you review your work before saving it permanently. If you stage changes, 'git diff' no longer shows them because it only compares unstaged changes. When there are no differences, 'git diff' outputs nothing.

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