Viewing commit history with git log - Mini Project: Build & Apply

Viewing commit history with git log

📖 Scenario: You are working on a small project and want to see the history of changes made to your files. This helps you understand what was changed and when.

🎯 Goal: Learn how to use the git log command to view the commit history of a Git repository.

📋 What You'll Learn

Initialize a Git repository

Make at least two commits

Use git log to view commit history

💡 Why This Matters

🌍 Real World

Viewing commit history helps developers track changes, find bugs, and understand project progress.

💼 Career

Knowing how to use <code>git log</code> is essential for software developers, DevOps engineers, and anyone working with version control.

1

Initialize a Git repository and create commits

Run git init to create a new Git repository. Then create a file named file.txt with the content Hello. Add the file with git add file.txt and commit it with the message First commit. Next, change the content of file.txt to Hello, world!, add it again, and commit with the message Second commit.

Git

# Run the commands to initialize git and create two commits
# Your code here

Hint

Use git init to start the repository. Use echo to write text to the file. Use git add and git commit -m to save changes.

2

Set up a configuration to limit log output

Create a variable called log_limit and set it to 1. This will be used to limit the number of commits shown in the log.

Git

git init

echo Hello > file.txt

git add file.txt

git commit -m "First commit"

echo Hello, world! > file.txt

git add file.txt

git commit -m "Second commit"

# Create a variable called log_limit and set it to 1
# Your code here

Hint

Use log_limit=1 to create the variable.

3

Use git log with the limit option

Run the command git log -n $log_limit to show only the most recent commit in the history.

Git

git init

echo Hello > file.txt

git add file.txt

git commit -m "First commit"

echo Hello, world! > file.txt

git add file.txt

git commit -m "Second commit"

log_limit=1

# Run git log with -n $log_limit to show limited commits
# Your code here

Hint

Use git log -n $log_limit to limit the number of commits shown.

4

Display the full commit history

Run git log without any limit to see all commits in the repository.

Git

git init

echo Hello > file.txt

git add file.txt

git commit -m "First commit"

echo Hello, world! > file.txt

git add file.txt

git commit -m "Second commit"

log_limit=1

git log -n $log_limit

# Run git log to show all commits
# Your code here

Hint

Simply run git log to see all commits.

Practice

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

easy

A. Deletes the last commit from the repository

B. Shows the history of commits made in the repository

C. Creates a new branch in the repository

D. Displays the current status of files in the repository

Solution

1. Step 1: Understand the purpose of git log

   The git log command is used to view the commit history in a Git repository.

2. Step 2: Compare with other Git commands

   Other commands like git status show file status, and git branch manages branches, but git log specifically shows commits.

3. Final Answer:

   Shows the history of commits made in the repository -> Option B

4. Quick Check:

   git log = commit history [OK]

Hint: Remember: log means history or record [OK]

Common Mistakes:

• Confusing git log with git status
• Thinking git log deletes commits
• Mixing git log with branch creation

2. Which of the following is the correct command to show a simplified one-line summary of each commit in Git?

easy

A. git log --oneline

B. git log --summary

C. git log --details

D. git log --short

Solution

1. Step 1: Identify the option for one-line commit summary

   The --oneline option condenses each commit to a single line showing the commit hash and message.

2. Step 2: Verify other options

   Options like --summary, --details, and --short are not valid git log options for this purpose.

3. Final Answer:

   git log --oneline -> Option A

4. Quick Check:

   --oneline = short commit list [OK]

Hint: Use --oneline for brief commit history [OK]

Common Mistakes:

• Using non-existent options like --summary
• Confusing --oneline with --short
• Forgetting the double dash before options

3. Given the command git log -2 --oneline, what will be the output?

medium

A. Shows the last two commits in a detailed multi-line format

B. Shows all commits except the last two

C. Shows the last two commits each summarized in one line

D. Shows the first two commits in the repository

Solution

1. Step 1: Understand the -2 option

   The -2 option limits the output to the last two commits only.

2. Step 2: Understand the --oneline option

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

3. Final Answer:

   Shows the last two commits each summarized in one line -> Option C

4. Quick Check:

   -2 + --oneline = last two commits short [OK]

Hint: Combine -n with --oneline for short recent commits [OK]

Common Mistakes:

• Thinking -2 shows first two commits
• Expecting detailed multi-line output with --oneline
• Confusing exclusion of commits with limiting output

4. You ran git log --oneline -p but got an error. What is the likely cause?

medium

A. The options --oneline and -p cannot be used together

B. You need to specify a branch name with the command

C. You must run git fetch before using git log

D. The repository has no commits yet

Solution

1. Step 1: Understand the options --oneline and -p

   --oneline shows a brief summary, while -p shows patch (diff) details.

2. Step 2: Check compatibility of options

   These two options conflict because one shows a short summary and the other shows detailed changes, so Git throws an error.

3. Final Answer:

   The options --oneline and -p cannot be used together -> Option A

4. Quick Check:

   --oneline + -p conflict = error [OK]

Hint: Avoid combining --oneline with -p; they conflict [OK]

Common Mistakes:

• Assuming branch name is required for git log
• Thinking git fetch fixes git log errors
• Ignoring that empty repo causes no output, not error

5. You want to see the commit history with each commit showing the author, date, and a one-line message, all in a compact format. Which command should you use?

hard

A. git log --graph --decorate

B. git log --oneline --author-date-order

C. git log -p --stat

D. git log --pretty=format:"%h - %an, %ar : %s"

Solution

1. Step 1: Understand the requirement for custom format

   You want author, date, and message in one line, so a custom format with --pretty=format: is needed.

2. Step 2: Analyze the format string

   %h is short commit hash, %an is author name, %ar is relative date, and %s is commit message. This matches the requirement.

3. Step 3: Check other options

   --oneline --author-date-order does not show author or date explicitly. -p --stat shows diffs and stats, not compact. --graph --decorate shows branch graph and refs, not author/date/message in one line.

4. Final Answer:

   git log --pretty=format:"%h - %an, %ar : %s" -> Option D

5. Quick Check:

   Custom format = author, date, message [OK]

Hint: Use --pretty=format for custom commit info display [OK]

Common Mistakes:

• Using --oneline without author or date info
• Expecting -p to show summary info
• Confusing --graph with formatting output