Split View: Git 마스터 가이드 — 기초부터 rebase, cherry-pick, bisect, worktree까지

# Check object type
git cat-file -t HEAD

# View commit object contents
git cat-file -p HEAD

# Explore the tree object
git ls-tree HEAD

# File movement flow between the three areas
# Working -> Staging
git add file.txt

# Staging -> Repository
git commit -m "feat: add file"

# Repository -> Working (restore a specific file)
git checkout HEAD -- file.txt

# Check where HEAD points
cat .git/HEAD
# ref: refs/heads/main

# Check which commit a branch points to
cat .git/refs/heads/main

# Enter detached HEAD state
git checkout HEAD~2

# Initialize / clone a repository
git init
git clone https://github.com/user/repo.git

# Check changes
git status
git diff                    # unstaged changes
git diff --staged           # staged changes
git diff HEAD               # all changes

# Stage & commit
git add -p                  # interactive partial staging
git commit -m "feat: login" # commit
git commit --amend          # amend last commit

# Remote sync
git fetch origin            # fetch remote changes only
git pull --rebase origin main  # fetch + rebase
git push origin feature/login  # push

# Create & switch branches
git branch feature/auth
git checkout -b feature/auth  # create + switch
git switch -c feature/auth    # recommended (Git 2.23+)

# List branches
git branch -a               # local + remote
git branch --merged          # fully merged branches
git branch -d feature/old    # safe delete
git branch -D feature/old    # force delete

# Clean up remote branches
git remote prune origin
git fetch -p

# Save current changes
git stash
git stash push -m "WIP: login form"

# List stashes
git stash list

# Restore
git stash pop               # pop and remove
git stash apply stash@{0}  # apply but keep

# Stash specific files only
git stash push -m "partial" -- src/auth.ts

# Convert a stash to a branch
git stash branch new-branch stash@{0}

# Merge feature branch into main
git checkout main
git merge feature/auth

# Rebase feature branch onto latest main
git checkout feature/auth
git rebase main

# Clean up the last 5 commits
git rebase -i HEAD~5

# Practical example: clean up before PR
# In the editor, modify like this:
# pick abc1234 feat: add login page
# squash def5678 fix: typo in login
# squash ghi9012 style: adjust padding
# -> 3 commits become 1

# Pick a specific commit
git cherry-pick abc1234

# Pick multiple commits at once
git cherry-pick abc1234 def5678

# Pick a range (abc excluded, def included)
git cherry-pick abc1234..def5678

# Apply changes without committing
git cherry-pick --no-commit abc1234

# Start bisect
git bisect start

# Mark current (buggy) as bad
git bisect bad

# Mark a known good commit
git bisect good v2.0.0

# Git checks out a midpoint commit -> test -> mark
git bisect good  # or git bisect bad

# Once found, reset
git bisect reset

# Automated bisect with a test script
git bisect start HEAD v2.0.0
git bisect run npm test

# Create a new worktree
git worktree add ../project-hotfix hotfix/critical-bug

# List worktrees
git worktree list

# Remove a worktree
git worktree remove ../project-hotfix

# Create a new branch while adding a worktree
git worktree add -b feature/new-ui ../project-ui

# View reflog
git reflog

# Recover after accidental reset --hard
git reflog
# Find: HEAD@{2}: commit: important feature
git reset --hard HEAD@{2}

# Recover a deleted branch
git reflog
git checkout -b recovered-branch HEAD@{5}

# View records within a time range
git reflog --since="2 days ago"

[alias]
    # Status & log
    st = status -sb
    lg = log --oneline --graph --decorate --all
    last = log -1 HEAD --stat

    # Branch
    co = checkout
    sw = switch
    br = branch -vv
    brd = branch -d

    # Commit
    cm = commit -m
    ca = commit --amend --no-edit
    undo = reset HEAD~1 --mixed

    # Diff
    df = diff --stat
    dfc = diff --cached

    # Stash
    sl = stash list
    sp = stash pop
    ss = stash push -m

    # Cleanup
    cleanup = "!git branch --merged | grep -v '\\*\\|main\\|develop' | xargs -n 1 git branch -d"

[core]
    editor = code --wait
    autocrlf = input          # macOS/Linux
    ignorecase = false
    pager = delta              # use delta pager

[pull]
    rebase = true              # always rebase on pull

[push]
    default = current          # push only current branch
    autoSetupRemote = true     # auto set upstream on push

[init]
    defaultBranch = main

[diff]
    tool = vscode
    colorMoved = default

[merge]
    conflictstyle = diff3      # 3-way conflict display
    tool = vscode

[rerere]
    enabled = true             # remember conflict resolutions

# Install
brew install git-delta

# Add to .gitconfig

[core]
    pager = delta

[interactive]
    diffFilter = delta --color-only

[delta]
    navigate = true
    line-numbers = true
    side-by-side = true

## Changes
- What changed and why

## Testing
- [ ] Added/updated unit tests
- [ ] Verified locally
- [ ] Edge cases validated

## Screenshots (for UI changes)

## Related Issues
- closes #123

# .github/CODEOWNERS

# Entire codebase
* @team-lead

# Frontend
/src/components/ @frontend-team
/src/pages/ @frontend-team

# Backend API
/src/api/ @backend-team

# Infrastructure
/terraform/ @devops-team
/k8s/ @devops-team

# Security-sensitive files
/src/auth/ @security-team @team-lead

type(scope): description

body (optional)

footer (optional)

# Examples
git commit -m "feat(auth): add Google OAuth login"
git commit -m "fix(api): handle null response from payment gateway"
git commit -m "docs(readme): update installation instructions"

# Breaking Change
git commit -m "feat(api)!: change response format to JSON:API"

git commit -m ":sparkles: add user profile page"
git commit -m ":bug: fix login redirect loop"
git commit -m ":recycle: refactor database connection pool"
git commit -m ":white_check_mark: add unit tests for auth module"

# Install
npm install -D @commitlint/cli @commitlint/config-conventional

# commitlint.config.js

module.exports = {
  extends: ['@commitlint/config-conventional'],
  rules: {
    'type-enum': [2, 'always', [
      'feat', 'fix', 'docs', 'style',
      'refactor', 'perf', 'test', 'chore', 'ci'
    ]],
    'subject-max-length': [2, 'always', 72],
  },
};

# Enable sparse-checkout
git sparse-checkout init --cone

# Specify only needed directories
git sparse-checkout set packages/frontend packages/shared

# Add a directory
git sparse-checkout add packages/backend

# Check current configuration
git sparse-checkout list

# Restore full checkout
git sparse-checkout disable

# Add an external repository
git subtree add --prefix=libs/shared-utils \
  https://github.com/org/shared-utils.git main --squash

# Pull changes
git subtree pull --prefix=libs/shared-utils \
  https://github.com/org/shared-utils.git main --squash

# Push changes back
git subtree push --prefix=libs/shared-utils \
  https://github.com/org/shared-utils.git main

# Nx: test only affected projects
npx nx affected --target=test --base=main --head=HEAD

# Turborepo: build only changed packages
npx turbo run build --filter=...[HEAD~1]

# In GitHub Actions: detect changes
# Compare against main in CI to process only changed packages

# 1. Find the original commit in reflog
git reflog show origin/main

# 2. Restore to the original commit
git push origin HEAD@{1}:main --force

# 3. Notify the team
# "main branch has been restored. Please run git pull --rebase."

# Block force push on main (GitHub Settings)
# Settings -> Branches -> Branch protection rules
# Enable "Restrict force pushes"

# Install BFG
brew install bfg

# Completely remove a file from all history
bfg --delete-files secrets.env

# Replace specific text patterns
bfg --replace-text passwords.txt

# Clean up
git reflog expire --expire=now --all
git gc --prune=now --aggressive

# Force push
git push --force

# Install & initialize Git LFS
brew install git-lfs
git lfs install

# Specify file patterns to track
git lfs track "*.psd"
git lfs track "*.zip"
git lfs track "assets/videos/*"

# .gitattributes is auto-generated -- commit it
git add .gitattributes
git commit -m "chore: configure Git LFS tracking"

# List LFS-tracked files
git lfs ls-files

# Migrate already-committed large files to LFS
git lfs migrate import --include="*.psd" --everything

# Revert the merge commit itself
git revert -m 1 MERGE_COMMIT_SHA

# -m 1: revert relative to the first parent (main)
# -m 2: revert relative to the second parent (feature)

# 1. Check reflog (available for 90 days)
git reflog

# 2. Recover from dangling objects
git fsck --lost-found

# 3. Worst case: recover from a teammate's local repo
# Ask them to push, or receive a bundle
git bundle create backup.bundle --all