Recovering lost commits with reflog in Git - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the command to show the reflog history.

Git

git [1]

Drag options to blanks, or click blank then click option'

Astatus

Breflog

Clog

Dbranch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'git log' instead of 'git reflog' because 'log' shows commit history but not HEAD movements.

Using 'git status' which shows working directory status, not reflog.

Using 'git branch' which lists branches, not reflog.

The git reflog command shows the history of HEAD changes, which helps recover lost commits.

2fill in blank

medium

Complete the command to reset HEAD to a specific reflog entry.

Git

git reset --hard [1]

Drag options to blanks, or click blank then click option'

Aorigin/main

BHEAD~1

CHEAD@{1}

Dmaster

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'HEAD~1' which refers to the parent commit, not reflog entry.

Using branch names like 'master' or 'origin/main' which do not refer to reflog entries.

HEAD@{1} refers to the previous position of HEAD in the reflog, useful for recovering lost commits.

3fill in blank

hard

Fix the error in the command to recover a lost commit by checking out a reflog commit.

Git

git checkout [1]

Drag options to blanks, or click blank then click option'

AHEAD~2

Borigin/HEAD

Cmain

DHEAD@{2}

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'HEAD~2' which is a commit parent reference, not reflog.

Using branch names which do not point to lost commits.

HEAD@{2} correctly references a reflog commit. Using HEAD~2 references commit parents, not reflog.

4fill in blank

hard

Fill both blanks to create a new branch from a lost commit found in reflog.

Git

git branch [1] [2]

Drag options to blanks, or click blank then click option'

Arecovered-branch

BHEAD@{3}

Cmain

Dorigin/main

Attempts:

3 left

💡 Hint

Common Mistakes

Using existing branch names instead of a new branch name.

Using branch names instead of reflog references for the commit.

Create a new branch named recovered-branch at the reflog commit HEAD@{3} to save the lost commit.

5fill in blank

hard

Fill all three blanks to reset the current branch to a lost commit and clean working directory.

Git

git reset --[1] [2] && git clean -[3]

Drag options to blanks, or click blank then click option'

Ahard

BHEAD@{4}

Cf

Dsoft

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'soft' reset which keeps changes and does not fully recover state.

Using wrong reflog syntax or branch names.

Forgetting to force clean untracked files.

git reset --hard HEAD@{4} resets the branch to the lost commit, and git clean -f removes untracked files to clean the working directory.

Practice

1. What is the primary purpose of git reflog in Git?

easy

A. To show a log of where HEAD and branch references have been recently

B. To permanently delete commits from the repository

C. To merge two branches automatically

D. To push commits to a remote repository

Solution

1. Step 1: Understand what reflog tracks

   Git reflog records changes to HEAD and branch tips, showing recent commit movements.

2. Step 2: Identify reflog's main use

   It helps find lost commits by listing recent HEAD positions, not deleting or merging.

3. Final Answer:

   To show a log of where HEAD and branch references have been recently -> Option A

4. Quick Check:

   Reflog = recent HEAD changes [OK]

Hint: Reflog shows recent HEAD moves, not branch merges or deletions [OK]

Common Mistakes:

• Confusing reflog with git log
• Thinking reflog deletes commits
• Assuming reflog pushes commits

2. Which command correctly recovers a lost commit using its reflog hash abc1234 by creating a new branch named recovered?

easy

A. git branch recovered && git checkout abc1234

B. git reset --hard recovered abc1234

C. git reflog checkout abc1234 recovered

D. git checkout -b recovered abc1234

Solution

1. Step 1: Understand how to create a branch from a commit hash

   The command git checkout -b <branch> <commit> creates and switches to a new branch at that commit.

2. Step 2: Check each option's correctness

   git checkout -b recovered abc1234 uses correct syntax. git branch recovered && git checkout abc1234 creates branch but checks out commit separately (detached HEAD). git reflog checkout abc1234 recovered is invalid syntax. git reset --hard recovered abc1234 misuses reset.

3. Final Answer:

   git checkout -b recovered abc1234 -> Option D

4. Quick Check:

   Create branch from commit: checkout -b [OK]

Hint: Use 'git checkout -b branch commit' to recover lost commit [OK]

Common Mistakes:

• Using git reflog checkout (invalid command)
• Creating branch and checkout separately causing detached HEAD
• Misusing git reset syntax

3. Given the following reflog output snippet:

abc1234 HEAD@{0}: commit: Fix typo
def5678 HEAD@{1}: commit: Add feature
789abcd HEAD@{2}: commit: Initial commit

What command will restore the commit with message 'Add feature'?

medium

A. git checkout HEAD@{2}

B. git checkout 789abcd

C. git checkout def5678

D. git checkout abc1234

Solution

1. Step 1: Identify the commit hash for 'Add feature'

   From reflog, 'Add feature' commit hash is def5678 at HEAD@{1}.

2. Step 2: Use git checkout with the correct hash

   Checking out def5678 restores that commit state.

3. Final Answer:

   git checkout def5678 -> Option C

4. Quick Check:

   Checkout commit by hash = def5678 [OK]

Hint: Match commit message to hash, then checkout that hash [OK]

Common Mistakes:

• Choosing wrong commit hash
• Using HEAD@{2} which is 'Initial commit'
• Confusing latest commit with target commit

4. You ran git reflog and found a lost commit hash abc1234. You tried git checkout abc1234 but got a detached HEAD warning. How do you fix this to recover the commit safely?

medium

A. Create a new branch at that commit using git checkout -b recovered abc1234

B. Run git reset --hard abc1234 immediately

C. Delete the reflog entry and try again

D. Push the commit hash to remote

Solution

1. Step 1: Understand detached HEAD state

   Checking out a commit hash puts you in detached HEAD, which is risky for new work.

2. Step 2: Create a branch to save the commit safely

   Use git checkout -b recovered abc1234 to create a branch and avoid losing commits.

3. Final Answer:

   Create a new branch at that commit using git checkout -b recovered abc1234 -> Option A

4. Quick Check:

   Fix detached HEAD by creating branch [OK]

Hint: Always create a branch from lost commit to avoid detached HEAD [OK]

Common Mistakes:

• Ignoring detached HEAD and continuing work
• Deleting reflog entries mistakenly
• Trying to push without branch

5. You accidentally reset your branch to an older commit, losing recent commits. You run git reflog and see:

abc1234 HEAD@{0}: reset: moving to abc1234
def5678 HEAD@{1}: commit: Add new feature
789abcd HEAD@{2}: commit: Fix bug

How do you restore your branch to include the lost 'Add new feature' commit?

hard

A. Delete reflog entries before abc1234

B. Run git reset --hard def5678 to move branch back to lost commit

C. Run git checkout abc1234 to stay at reset point

D. Run git merge def5678 from abc1234

Solution

1. Step 1: Identify lost commit hash from reflog

   The lost commit 'Add new feature' is at def5678 (HEAD@{1}).

2. Step 2: Use git reset to move branch pointer back

   Running git reset --hard def5678 restores branch to that commit, recovering lost work.

3. Final Answer:

   Run git reset --hard def5678 to move branch back to lost commit -> Option B

4. Quick Check:

   Reset branch to lost commit hash [OK]

Hint: Use git reset --hard with reflog hash to recover lost commits [OK]

Common Mistakes:

• Checking out reset commit instead of resetting branch
• Deleting reflog entries unnecessarily
• Trying to merge without branch pointer