Viewing commit history with git log - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Understanding git log output with --oneline

What is the output of the command git log --oneline in a repository with three commits?

A Only the commit hashes without messages

B A detailed list of commits with author, date, and full commit message

C A list of commit hashes and their first line messages, one per line

D An error message saying the option is invalid

💡 Hint

The --oneline option shortens the output to one line per commit.

The git log --oneline command shows each commit as a short hash followed by the first line of the commit message, making it easy to scan commit history quickly.

💻 Command Output

intermediate

Effect of --graph option in git log

What does the git log --graph command add to the commit history output?

A A list of commits sorted by author name

B A summary of changed files per commit

C Only commits from the current branch

D A visual ASCII graph showing branch and merge history alongside commits

💡 Hint

Think about how git shows branching and merging visually.

The --graph option adds an ASCII art graph on the left side of the log output to visualize branches and merges.

❓ Configuration

advanced

Customizing git log output with pretty format

Which git log command produces output showing only the commit hash and author name separated by a dash?

A git log --format="%H %ae"

B git log --pretty=format:"%h - %an"

C git log --oneline --author

D git log --pretty=short

💡 Hint

Use the --pretty=format: option with placeholders for hash and author name.

The --pretty=format:"%h - %an" option formats each commit line to show the short hash (%h), a dash, and the author name (%an).

❓ Troubleshoot

advanced

Diagnosing empty git log output

You run git log but see no output. What is the most likely reason?

A The repository has no commits yet

B The git log command is deprecated

C You are not connected to the internet

D Your terminal does not support git commands

💡 Hint

Think about what git log shows and when it would be empty.

If there are no commits in the repository, git log will show no output because there is no history to display.

✅ Best Practice

expert

Efficiently viewing last 5 commits with concise info

Which command best shows the last 5 commits with short hashes and commit messages in a compact form?

A git log -5 --oneline

B git log --since=5

C git log -n 5 --pretty=full

D git log --limit=5 --short

💡 Hint

Use the option that limits number of commits and shortens output.

git log -5 --oneline shows the last 5 commits with short hashes and one-line messages, which is concise and efficient.

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