tools-git-advanced

# Advanced Git Operations ## Overview Advanced git commands for complex workflows, history manipulation, and debugging. Use this skill for rebasing, cherry-picking, finding bugs, and recovering from mistakes. ## When to Use - Rebasing branches and cleaning history - Cherry-picking specific commits - Finding which commit introduced a bug - Recovering lost commits - Complex merge scenarios - Stash management ## Interactive Rebase ### Start Rebase ```bash git rebase -i HEAD~5 # Last 5 commits git rebase -i main # Onto main git rebase -i --root # All commits ``` ### Rebase Commands | Command | Action | |---------|--------| | `pick` | Keep commit as-is | | `reword` | Change commit message | | `edit` | Stop to amend commit | | `squash` | Combine with previous | | `fixup` | Combine, discard message | | `drop` | Remove commit | | `exec` | Run shell command | ### Common Rebase Operations ```bash # Squash last 3 commits git rebase -i HEAD~3 # Change 'pick' to 'squash' for commits to combine # Reorder commits git rebase -i HEAD~5 # Reorder lines in editor # Edit commit message git rebase -i HEAD~3 # Change 'pick' to 'reword' # Split a commit git rebase -i HEAD~3 # Change 'pick' to 'edit' git reset HEAD~ git add -p && git commit git add -p && git commit git rebase --continue ``` ### Rebase onto Branch ```bash git rebase main # Rebase current onto main git rebase main feature # Rebase feature onto main git rebase --onto main A B # Rebase B onto main, starting from A ``` ### Abort/Continue ```bash git rebase --continue # After resolving conflicts git rebase --skip # Skip current commit git rebase --abort # Cancel rebase ``` ## Cherry-Pick ```bash git cherry-pick <commit> # Apply single commit git cherry-pick A B C # Multiple commits git cherry-pick A..B # Range (exclusive A) git cherry-pick A^..B # Range (inclusive A) git cherry-pick -n <commit> # No auto-commit git cherry-pick -x <commit> # Add source reference git cherry-pick --abort # Cancel git cherry-pick --continue # After conflict ``` ### Cherry-Pick from Another Branch ```bash git log other-branch --oneline # Find commit hash git cherry-pick abc123 # Apply it ``` ## Git Bisect (Find Bug) ### Basic Bisect ```bash git bisect start # Start bisecting git bisect bad # Current commit is bad git bisect good v1.0 # Known good commit # Git checks out middle commit # Test and mark: git bisect good # This commit is OK git bisect bad # This commit has bug # Repeat until found git bisect reset # End bisect ``` ### Automated Bisect ```bash git bisect start HEAD v1.0 git bisect run npm test # Auto-run test git bisect run ./test-script.sh # Custom script # Script: exit 0 = good, exit 1 = bad ``` ### Bisect Log ```bash git bisect log # Show bisect history git bisect log > bisect.log # Save for replay git bisect replay bisect.log # Replay session ``` ## Reflog (Recovery) ### View Reflog ```bash git reflog # HEAD history git reflog show main # Branch history git reflog --date=relative # With timestamps ``` ### Recover Lost Commits ```bash # After bad reset git reflog git reset --hard HEAD@{2} # Go back 2 moves # Recover deleted branch git reflog git checkout -b recovered HEAD@{5} # Find lost stash git fsck --unreachable | grep commit git show <commit> ``` ## Stash Management ### Basic Stash ```bash git stash # Stash changes git stash -u # Include untracked git stash -a # Include ignored git stash push -m "message" # With message git stash push path/to/file # Specific files ``` ### List & Apply ```bash git stash list # List stashes git stash show # Show latest diff git stash show -p stash@{1} # Full diff git stash apply # Apply latest git stash apply stash@{2} # Apply specific git stash pop # Apply and remove git stash drop stash@{1} # Remove stash git stash clear # Remove all ``` ### Branch from Stash ```bash git stash branch newbranch # Create branch from stash ``` ## Reset vs Revert ### Reset (Rewrite History) ```bash git reset --soft HEAD~1 # Undo commit, keep staged git reset --mixed HEAD~1 # Undo commit, unstage (default) git reset --hard HEAD~1 # Undo commit, discard changes git reset --hard origin/main # Match remote exactly ``` ### Revert (Safe, Creates Commit) ```bash git revert <commit> # Revert single commit git revert HEAD~3..HEAD # Revert range git revert -n <commit> # No auto-commit git revert -m 1 <merge-commit> # Revert merge ``` ## Amending ```bash git commit --amend # Edit last commit message git commit --amend -m "new msg" # Replace message git commit --amend --no-edit # Add staged, keep message git commit --amend --author="Name <email>" # Fix author ``` ## Clean & Prune ```bash git clean -n # Dry run git clean -f # Remove untracked files git clean -fd # Include directories git clean -fX # Only ignored files git gc # Garbage collect git prune # Remove unreachable objects ``` ## Worktrees ```bash git worktree list # List worktrees git worktree add ../feature feature-branch git worktree add ../hotfix -b hotfix git worktree remove ../feature # Remove worktree git worktree prune # Clean stale ``` ## Blame & Log ```bash git blame <file> # Who changed each line git blame -L 10,20 <file> # Lines 10-20 git log -p <file> # File history with diffs git log --follow <file> # Follow renames git log -S "searchterm" # Commits adding/removing text git log -G "regex" # Commits matching regex git log --all --oneline --graph # Visual history ``` ## Patches ```bash git format-patch HEAD~3 # Create patch files git format-patch main..feature # Branch patches git apply patch.patch # Apply patch git am patch.patch # Apply as commit ``` ## Troubleshooting | Scenario | Solution | |----------|----------| | Undo last commit | `git reset --soft HEAD~1` | | Undo pushed commit | `git revert <commit>` | | Wrong branch commit | Cherry-pick to correct branch | | Lost commits | `git reflog` to find and recover | | Bad rebase | `git rebase --abort` or reflog | | Merge conflict hell | `git merge --abort` and retry | | Detached HEAD | `git checkout -b newbranch` |