Git Reflog Deep Dive: Recovering Lost Commits and Understanding Git’s Safety Net

Git Reflog Deep Dive: Recovering Lost Commits and Understanding Git’s Safety Net

Git’s reflog is a hidden gem that acts as a safety net, recording every action you take in your repository. Whether you’ve accidentally deleted a branch, reset to the wrong commit, or lost track of your HEAD, the reflog can help you recover. In this blog, we’ll explore the inner workings of reflog, how to use it effectively, and practical examples for recovering lost data.

Table of Contents

• What is Reflog?
• Viewing and Filtering Reflog Entries
• Recovering Lost Commits and Deleted Branches
• Advanced Reflog Techniques
• Exercise: Mastering Reflog

What is Reflog?

The reflog is a chronological record of all changes to the tip of branches and other references (e.g., HEAD). It tracks:

• Commit hashes.
• Actions like commit, checkout, reset, and rebase.
• Timestamps for each action.

Viewing and Filtering Reflog Entries

View the reflog for the current branch or HEAD:

  git reflog
          

Filter by specific actions or limit entries:

  # Filter by resets
  git reflog | grep "reset"
  
  # Limit to 10 entries
  git reflog -n 10
          

Recovering Lost Commits and Deleted Branches

To recover a lost commit:

  # Identify the commit hash in reflog
  git reflog
  
  # Restore the commit
  git checkout <commit-hash>
  git checkout -b recovered-branch <commit-hash>
          

To restore a deleted branch:

  # Find the last commit in reflog
  git reflog
  
  # Recreate the branch
  git checkout -b <branch-name> <commit-hash>
          

Advanced Reflog Techniques

Expire and clean up old reflog entries:

  # Expire entries older than 30 days
  git reflog expire --expire=30.days --all
  
  # Run garbage collection
  git gc --prune=now
          

Exercise: Mastering Reflog

Practice using reflog:

• Create a few commits, then reset to an earlier commit using git reset --hard. Use git reflog to identify and recover the lost commits.
• Delete a branch and recreate it using the reflog.
• Run git reflog expire and git gc to clean up unused entries.

Coming Up Next

In the next part of this series, we’ll explore disaster recovery techniques, including restoring corrupted repositories, recovering lost objects, and implementing backup strategies.