git-advanced-operations

Git Advanced Operations

Power-user Git workflows for rewriting history, recovery, automation, and large repo management.

Core Principles

1. Understand the object model - Commits are immutable snapshots; branches are movable pointers; HEAD tracks your current position
2. Reflog is your safety net - Every HEAD movement is recorded for 90 days; almost nothing in Git is truly lost
3. Non-destructive by default - Prefer operations that create new commits over those that destroy history
4. Never rewrite shared history - Only rebase or amend commits that have not been pushed to a shared branch
5. Automate repetitive checks - Use hooks to enforce standards before code leaves your machine

Interactive Rebase

Rewrite, reorder, squash, and clean up commit history before sharing

# Rebase last 5 commits interactively
git rebase -i HEAD~5

# In the editor, change pick to the desired action:
# pick   abc1234 Add user model
# squash abc1235 Fix typo in user model
# reword abc1236 Add auth middleware
# edit   abc1237 Add login endpoint
# drop   abc1238 WIP debugging

# Autosquash: auto-arrange fixup/squash commits
git commit --fixup=abc1234
git rebase -i --autosquash HEAD~5

# Rebase onto a different base branch
git rebase --onto main feature-base feature-branch

See interactive-rebase.md for:

• Squash vs fixup vs reword workflows
• Edit mode for splitting commits
• Autosquash with --fixup and --squash commits
• Rebase onto for transplanting branches
• Handling rebase conflicts

Reflog and Recovery

Recover lost commits and undo destructive operations

# View recent HEAD movements
git reflog --date=relative

# Recover a commit after accidental reset
git reflog
# abc1234 HEAD@{2}: commit: important work
git checkout -b recovery-branch abc1234

# Undo a rebase by resetting to pre-rebase state
git reflog
# abc1234 HEAD@{5}: rebase (start): checkout main
git reset --hard HEAD@{5}

# Recover a deleted branch
git reflog | grep "checkout: moving from deleted-branch"
git checkout -b restored-branch abc1234