Repository (committed history) in Git - Mini Project: Build & Apply

Explore Git Repository Committed History

📖 Scenario: You are working on a small project and want to understand the history of changes made to your files. Git keeps track of all changes in a repository as commits. Each commit has a unique ID and a message describing the change.Learning how to view this committed history helps you see what was changed, when, and by whom.

🎯 Goal: Learn how to check the committed history of a Git repository using basic Git commands.

📋 What You'll Learn

Use the git log command to view commit history

Use the git log --oneline command for a concise view

Understand commit IDs and messages

Practice reading commit history output

💡 Why This Matters

🌍 Real World

Developers use Git commit history to track changes, find bugs, and understand project progress.

💼 Career

Knowing how to read Git history is essential for collaboration and code review in software development jobs.

1

Initialize a Git repository

Run git init in your project folder to create a new Git repository.

Git

# Run the command to initialize a Git repository
# Your code here

Hint

Type git init exactly to start tracking your project with Git.

2

Create and commit a file

Create a file named README.md with the text Initial commit. Then run git add README.md and git commit -m "Add README file" to save this change.

Git

git init
# Create README.md with text 'Initial commit'
# Add and commit the file
# Your code here

Hint

Use echo to create the file, then add and commit it with the exact commands.

3

View the full commit history

Run git log to see the detailed commit history including commit ID, author, date, and message.

Git

git init

echo "Initial commit" > README.md

git add README.md

git commit -m "Add README file"
# Run git log to view commit history
# Your code here

Hint

Simply type git log to see the full commit details.

4

View a concise commit history

Run git log --oneline to see a short summary of commits with just the commit ID and message.

Git

git init

echo "Initial commit" > README.md

git add README.md

git commit -m "Add README file"

git log
# Run git log --oneline for a short summary
# Your code here

Hint

Use git log --oneline to get a brief view of your commit history.

Practice

1. What does the git log command show in a Git repository?

easy

A. A list of all commits made in the repository history

B. The current status of files in the working directory

C. The list of branches in the repository

D. The remote repository URLs configured

Solution

1. Step 1: Understand the purpose of git log

   The git log command is designed to show the commit history of the repository, listing all saved changes.

2. Step 2: Differentiate from other commands

   Commands like git status show file changes, git branch shows branches, and git remote -v shows remote URLs, not commit history.

3. Final Answer:

   A list of all commits made in the repository history -> Option A

4. Quick Check:

   Commit history = git log output [OK]

Hint: Remember: git log = commit history list [OK]

Common Mistakes:

• Confusing git log with git status
• Thinking git log shows branches
• Mixing git log with remote info commands

2. Which of the following commands correctly shows a short, one-line summary of each commit in the history?

easy

A. git log --short

B. git log --oneline

C. git show --summary

D. git status --oneline

Solution

1. Step 1: Identify the correct flag for short commit view

   The --oneline option with git log shows each commit in a single line summary.

2. Step 2: Verify other options are incorrect

   git log --short is invalid, git show --summary shows details of one commit, and git status --oneline is invalid syntax.

3. Final Answer:

   git log --oneline -> Option B

4. Quick Check:

   Short commit list = git log --oneline [OK]

Hint: Use --oneline with git log for brief commit list [OK]

Common Mistakes:

• Using invalid flags like --short
• Confusing git show with git log
• Trying to use git status for commit history

3. Given this command output from git log --oneline:

f3a1b2c Fix typo in README
9d8e7f6 Add new feature X
4b3c2d1 Initial commit

What is the hash of the commit that added the new feature?

medium

A. 9d8e7f6

B. f3a1b2c

C. 4b3c2d1

D. Cannot tell from this output

Solution

1. Step 1: Read the commit messages and hashes

   The commit message "Add new feature X" corresponds to the hash 9d8e7f6.

2. Step 2: Match the message to the correct hash

   Each line shows the hash first, then the message. So the hash for adding the feature is 9d8e7f6.

3. Final Answer:

   9d8e7f6 -> Option A

4. Quick Check:

   Commit message matches hash 9d8e7f6 [OK]

Hint: First word is hash, rest is message in git log --oneline [OK]

Common Mistakes:

• Picking the wrong hash for the message
• Thinking hashes are at the end
• Assuming output is incomplete

4. You ran git log --oneline but got an error: error: unknown option `--oneline'. What is the most likely cause?

medium

A. You typed the command in the wrong folder

B. You must run git fetch before using --oneline

C. You need to add git log --oneline --all to fix it

D. Your Git version is too old and does not support --oneline

Solution

1. Step 1: Understand the error message

   The error says the option --oneline is unknown, meaning Git does not recognize it.

2. Step 2: Identify the cause

   This usually happens if the Git version is old and does not support the --oneline flag.

3. Final Answer:

   Your Git version is too old and does not support --oneline -> Option D

4. Quick Check:

   Unknown option error = outdated Git version [OK]

Hint: Unknown option often means Git version is outdated [OK]

Common Mistakes:

• Assuming wrong folder causes option error
• Thinking fetch fixes option errors
• Adding unrelated flags to fix syntax

5. You want to see a quick summary of the last 3 commits in your repository, each on one line. Which command should you use?

hard

A. git log --oneline --last 3

B. git log --3 --oneline

C. git log --oneline -n 3

D. git log --limit=3 --oneline

Solution

1. Step 1: Identify the correct option to limit commits

   The -n 3 or --max-count=3 option limits the number of commits shown.

2. Step 2: Combine with --oneline for short output

   Using git log --oneline -n 3 shows the last 3 commits in one-line format.

3. Step 3: Check other options for correctness

   --3 is invalid, --last 3 and --limit=3 are not valid git log options.

4. Final Answer:

   git log --oneline -n 3 -> Option C

5. Quick Check:

   Limit commits with -n, short view with --oneline [OK]

Hint: Use -n with --oneline to limit commits shown [OK]

Common Mistakes:

• Using invalid flags like --last or --limit
• Trying --3 which is invalid
• Mixing order of options incorrectly