Reflog for finding lost commits in Git - Step-by-Step Execution

Process Flow - Reflog for finding lost commits

Commit made

↓

HEAD moves to new commit

↓

Commit lost by reset/rebase

↓

Use git reflog

↓

Find lost commit SHA

↓

Recover commit with git checkout or git reset

This flow shows how commits move HEAD, how commits can be lost by reset or rebase, and how reflog helps find and recover them.

Execution Sample

Git

git commit -m "Add feature"
git reset --hard HEAD~1
git reflog
# find lost commit SHA
git checkout <SHA>

This sequence creates a commit, resets HEAD to previous commit losing the new one, then uses reflog to find and recover the lost commit.

Process Table

Step	Command	HEAD Position	Action	Result
1	git commit -m "Add feature"	commit1	Create new commit	HEAD points to commit1
2	git reset --hard HEAD~1	commit0	Move HEAD back one commit	commit1 becomes unreachable (lost)
3	git reflog	commit0	Show HEAD history	Lists commit1 as recent HEAD position
4	git checkout <commit1 SHA>	commit1	Checkout lost commit	HEAD points to recovered commit1

💡 Lost commit found in reflog and recovered by checkout

Status Tracker

Variable	Start	After Step 1	After Step 2	After Step 4
HEAD	commit0	commit1	commit0	commit1
commit1	does not exist	exists and pointed by HEAD	unreachable (lost)	checked out and reachable

Key Moments - 3 Insights

Why does the lost commit still appear in reflog after reset?

Because reflog records all HEAD movements including resets, so even unreachable commits are listed (see execution_table step 3).

Can I recover a lost commit if it is not in reflog?

No, reflog only tracks recent HEAD changes. If the commit is too old and reflog expired, recovery is not possible.

What does git reset --hard do to the commit?

It moves HEAD and updates working files, making the newer commit unreachable but still in reflog temporarily (see step 2).

Visual Quiz - 3 Questions

Look at the execution table, what is HEAD pointing to after step 2?

A commit0

B commit1

C commit2

D No commit

💡 Hint

Check the 'HEAD Position' column for step 2 in the execution_table.

At which step does the lost commit become reachable again?

A Step 1

B Step 4

C Step 2

D Step 3

💡 Hint

Look for when HEAD points back to commit1 in the execution_table.

If you did not run git reflog, how would the recovery process change?

A The commit would be deleted immediately

B You could still recover the commit easily

C You would not know the lost commit SHA to recover

D HEAD would automatically point to the lost commit

💡 Hint

Refer to the importance of reflog in finding lost commit SHA in the concept_flow.

Concept Snapshot

git reflog records all HEAD movements including resets.
Lost commits become unreachable but are listed in reflog.
Use 'git reflog' to find lost commit SHA.
Recover lost commits with 'git checkout <SHA>' or 'git reset <SHA>'.
Reflog entries expire after some time, so recover quickly.

Full Transcript

This lesson shows how git commits move HEAD pointer and how commands like reset can make commits unreachable or lost. The git reflog command records all HEAD movements, including resets and rebases, so it helps find lost commits by showing their SHA hashes. By running git reflog, you can see the history of HEAD positions and find the SHA of a lost commit. Then you can recover it by checking it out or resetting HEAD to it. The execution table traces these steps: making a commit, resetting HEAD back, listing reflog, and recovering the commit. Variables like HEAD and commit1 change state accordingly. Key moments clarify why reflog still shows lost commits and the limits of recovery. The quiz tests understanding of HEAD positions and recovery steps. Remember, reflog is a safety net for recent lost commits but entries expire over time.

Practice

1. What is the primary purpose of git reflog?

easy

A. To list all remote branches

B. To permanently delete commits from the repository

C. To record where HEAD and branches have pointed recently

D. To merge two branches automatically

Solution

1. Step 1: Understand what reflog tracks

   Reflog records the history of where HEAD and branch references have pointed, including commits that might be lost after resets or rebases.

2. Step 2: Compare options with reflog purpose

   Only To record where HEAD and branches have pointed recently correctly describes reflog's role. Options B, C, and D describe unrelated git functions.

3. Final Answer:

   To record where HEAD and branches have pointed recently -> Option C

4. Quick Check:

   Reflog tracks HEAD history = A [OK]

Hint: Reflog shows recent HEAD moves, like a safety net [OK]

Common Mistakes:

• Confusing reflog with git log
• Thinking reflog deletes commits
• Assuming reflog lists remote branches

2. Which command correctly shows the reflog entries?

easy

A. git reflog

B. git reflog list

C. git reflog -a

D. git reflog --show

Solution

1. Step 1: Recall the basic reflog command

   The simplest and correct command to show reflog entries is git reflog.

2. Step 2: Evaluate other options

   git reflog --show is invalid; git reflog list and git reflog -a are invalid commands.

3. Final Answer:

   git reflog -> Option A

4. Quick Check:

   Basic reflog command = git reflog [OK]

Hint: Use just 'git reflog' to see recent HEAD moves [OK]

Common Mistakes:

• Adding unnecessary subcommands like 'list'
• Using invalid flags like '-a'
• Confusing reflog with git log

3. After running git reset --hard HEAD~1, you realize you lost a commit. Which command helps you find the lost commit's hash?

medium

A. git reflog

B. git status

C. git branch

D. git log --oneline

Solution

1. Step 1: Understand what happens after reset

   git reset --hard HEAD~1 moves HEAD back one commit, making the latest commit unreachable but still in reflog.

2. Step 2: Identify command to find lost commit

   git reflog shows recent HEAD positions including the lost commit's hash. Other commands won't show unreachable commits.

3. Final Answer:

   git reflog -> Option A

4. Quick Check:

   Reflog shows lost commits after reset = C [OK]

Hint: Use reflog to find commits lost by reset [OK]

Common Mistakes:

• Using git status which shows working tree only
• Using git branch which lists branches, not commits
• Using git log which hides unreachable commits

4. You ran git reset --hard HEAD~2 but want to restore the latest commit. Which command correctly resets to the lost commit using reflog?

medium

A. git reset --hard HEAD@{2}

B. git reset --hard origin/main

C. git reset --hard HEAD~1

D. git reset --hard HEAD@{1}

Solution

1. Step 1: Understand reflog indexing

   After resetting HEAD back two commits, reflog entries show HEAD@{0} as current, HEAD@{1} as previous position (the lost commit), and HEAD@{2} as older.

2. Step 2: Choose correct reflog entry to restore

   To restore the latest lost commit, reset to HEAD@{1} which points to it. HEAD@{2} is older, HEAD~1 is relative to current HEAD, and origin/main may differ.

3. Final Answer:

   git reset --hard HEAD@{1} -> Option D

4. Quick Check:

   Use HEAD@{1} to restore last HEAD position [OK]

Hint: Reset to HEAD@{1} to undo last reset [OK]

Common Mistakes:

• Using HEAD@{2} which is older than needed
• Using HEAD~1 which is relative to current HEAD
• Resetting to origin/main which may differ

5. You accidentally deleted a branch with important commits. How can you recover the lost commits using reflog?

hard

A. Run git branch -d to restore the branch

B. Find the commit hash in git reflog and create a new branch at that hash

C. Use git reset --hard origin/branch-name to recover commits

D. Re-clone the repository to get the branch back

Solution

1. Step 1: Locate lost commits in reflog

   Deleted branch commits remain in reflog as recent HEAD positions or branch references before deletion.

2. Step 2: Create a new branch at the lost commit hash

   After finding the commit hash in reflog, use git branch new-branch-name <commit-hash> to restore the branch with lost commits.

3. Final Answer:

   Find the commit hash in git reflog and create a new branch at that hash -> Option B

4. Quick Check:

   Reflog + new branch recovers deleted commits [OK]

Hint: Use reflog hash to recreate deleted branch [OK]

Common Mistakes:

• Trying to delete branch again to restore it
• Resetting to origin which may not have deleted commits
• Re-cloning loses local lost commits