Repository (committed history) in Git - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a repository in Git?

A repository is a storage space where your project files and their entire history of changes are saved. It keeps track of all versions of your files.

beginner

What does git commit do?

It saves a snapshot of your current changes to the repository's history. Think of it like taking a photo of your project at a moment in time.

beginner

Why is committed history important?

Committed history lets you see what changed, when, and who changed it. It helps you fix mistakes by going back to earlier versions.

intermediate

What is a commit hash?

A commit hash is a unique ID for each commit. It looks like a long string of letters and numbers and helps you find that exact snapshot later.

beginner

How can you view the committed history in Git?

Use the command git log to see a list of commits with details like author, date, and message.

What command saves your changes to the Git repository history?

A git clone

B git push

C git commit

D git status

git commit saves your changes as a snapshot in the repository history.

What does the commit hash represent?

A A unique ID for each commit

B The size of the repository

C The name of the branch

D The current working directory

The commit hash uniquely identifies each commit snapshot.

Which command shows the list of past commits?

A git branch

B git log

C git add

D git init

git log displays the commit history.

Why is committed history useful?

A To track changes and fix mistakes

B To delete files permanently

C To speed up your computer

D To create new files automatically

Committed history helps track changes and revert to earlier versions if needed.

What happens if you don’t commit your changes?

A Repository is deleted

B Changes are automatically saved

C Git creates a new branch

D Changes are not saved in history

Without committing, changes remain only in your working area and are not saved in the repository history.

Explain what a Git repository's committed history is and why it matters.

Think about how saving versions of a document helps you go back if needed.

Describe the role of the git commit command in managing repository history.

Imagine taking a photo of your project to remember its state.

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