Git

Comprehensive guide for git operations, GitHub CLI usage, commit practices, and version control workflows.

Git CLI Essentials

Status & Information

# Current state
git status                    # Working tree status
git status -sb                # Short format with branch info

# View changes
git diff                      # Unstaged changes
git diff --staged             # Staged changes
git diff HEAD~3               # Last 3 commits
git diff main...HEAD          # Changes since branching from main

# History
git log --oneline -20         # Last 20 commits, compact
git log --graph --oneline     # Visual branch history
git log --stat                # With file change stats
git log -p path/to/file       # History of specific file
git log --author="name"       # Filter by author

# Blame & inspection
git blame path/to/file        # Line-by-line attribution
git show <commit>             # Show commit details
git show <commit>:path/file   # Show file at specific commit

Staging & Committing

# Stage changes
git add <file>                # Stage specific file
git add .                     # Stage all changes
git add -p                    # Interactive staging (patch mode)
git add -u                    # Stage modified/deleted, not new

# Unstage
git restore --staged <file>   # Unstage file (keep changes)
git reset HEAD <file>         # Alternative unstage

# Commit
git commit -m "message"       # Commit with message
git commit                    # Open editor for message
git commit -am "message"      # Stage tracked + commit
git commit --amend            # Amend last commit (CAUTION)
git commit --amend --no-edit  # Amend without changing message

Branches

# List & info
git branch                    # List local branches
git branch -a                 # List all (local + remote)
git branch -vv                # With tracking info

# Create & switch
git branch <name>             # Create branch
git switch <name>             # Switch to branch
git switch -c <name>          # Create and switch
git checkout -b <name>        # Alternative create+switch

# Delete
git branch -d <name>          # Delete (safe - checks merged)
git branch -D <name>          # Force delete (CAUTION)

# Rename
git branch -m <old> <new>     # Rename branch

Remote Operations

# Fetch & pull
git fetch                     # Fetch all remotes
git fetch origin              # Fetch specific remote
git pull                      # Fetch + merge
git pull --rebase             # Fetch + rebase (cleaner history)

# Push
git push                      # Push current branch
git push -u origin <branch>   # Push and set upstream
git push --force-with-lease   # Safe force push (CAUTION)
git push --force              # Force push (DANGER)

# Remote management
git remote -v                 # List remotes
git remote add <name> <url>   # Add remote
git remote set-url origin <url>  # Change remote URL

Merging & Rebasing

# Merge
git merge <branch>            # Merge branch into current
git merge --no-ff <branch>    # Merge with merge commit
git merge --abort             # Abort failed merge

# Rebase
git rebase main               # Rebase onto main
git rebase -i HEAD~3          # Interactive rebase last 3
git rebase --abort            # Abort failed rebase
git rebase --continue         # Continue after fixing conflicts

# Cherry-pick
git cherry-pick <commit>      # Apply specific commit
git cherry-pick --abort       # Abort cherry-pick

Undoing Changes

# Discard working changes
git restore <file>            # Discard file changes
git restore .                 # Discard all changes
git checkout -- <file>        # Alternative discard

# Reset commits
git reset --soft HEAD~1       # Undo commit, keep staged
git reset --mixed HEAD~1      # Undo commit, keep unstaged (default)
git reset --hard HEAD~1       # Undo commit, discard changes (DANGER)

# Revert (safe undo)
git revert <commit>           # Create commit that undoes changes
git revert HEAD               # Revert last commit

# Recovery
git reflog                    # View all HEAD movements
git reset --hard <reflog-ref> # Recover lost commits

Stashing

git stash                     # Stash changes
git stash -m "message"        # Stash with message
git stash list                # List stashes
git stash pop                 # Apply and remove latest
git stash apply               # Apply without removing
git stash drop                # Remove latest stash
git stash clear               # Remove all stashes

GitHub CLI (gh)

Authentication

gh auth login                 # Interactive login
gh auth status                # Check auth status
gh auth logout                # Logout

Pull Requests

# Create
gh pr create                  # Interactive PR creation
gh pr create --title "..." --body "..."
gh pr create --draft          # Create as draft
gh pr create --base main      # Specify base branch

# List & view
gh pr list                    # List open PRs
gh pr list --state all        # All PRs
gh pr view                    # View current branch's PR
gh pr view <number>           # View specific PR
gh pr view --web              # Open in browser

# Review & merge
gh pr review                  # Start review
gh pr review --approve        # Approve PR
gh pr review --request-changes -b "feedback"
gh pr merge                   # Merge PR
gh pr merge --squash          # Squash merge
gh pr merge --rebase          # Rebase merge
gh pr merge --delete-branch   # Delete branch after merge

# Checkout
gh pr checkout <number>       # Checkout PR locally

Issues

# Create & list
gh issue create               # Interactive issue creation
gh issue create --title "..." --body "..."
gh issue list                 # List open issues
gh issue view <number>        # View issue

# Manage
gh issue close <number>       # Close issue
gh issue reopen <number>      # Reopen issue
gh issue comment <number> -b "..."  # Add comment

Repository

gh repo view                  # View current repo
gh repo clone <owner/repo>    # Clone repository
gh repo fork                  # Fork current repo
gh repo create                # Create new repo

Workflows & Actions

gh run list                   # List workflow runs
gh run view <id>              # View run details
gh run watch <id>             # Watch run in progress
gh run rerun <id>             # Rerun workflow

gh workflow list              # List workflows
gh workflow run <name>        # Trigger workflow

API Access

gh api repos/{owner}/{repo}/pulls
gh api repos/{owner}/{repo}/issues
gh api repos/{owner}/{repo}/pulls/<n>/comments

Conventional Commits

Format

<type>(<scope>): <description>

[optional body]

[optional footer(s)]

Types

Examples

# Feature
git commit -m "feat(auth): add JWT refresh token support"

# Bug fix
git commit -m "fix(api): handle null response in user endpoint"

# Breaking change
git commit -m "feat(api)!: remove deprecated v1 endpoints

BREAKING CHANGE: v1 API endpoints are no longer available"

# With issue reference
git commit -m "fix(cart): prevent negative quantities

Closes #123"

# Multi-line (use editor)
git commit
# Opens editor:
# feat(dashboard): add real-time notifications
#
# - Implement WebSocket connection
# - Add notification bell component
# - Store notifications in local state
#
# Closes #456

Scopes (Project-Specific)

Common scopes:

• api, auth, ui, db, config
• deps, ci, docs, test
• Feature names: cart, checkout, profile

Branching Strategies

Trunk-Based Development (Recommended)

main ─────●─────●─────●─────●─────●─────
           \   /       \   /
            ●─●         ●─●
         (short-lived feature branches)

Rules:

• Main is always deployable
• Feature branches SHOULD live < 2 days
• MUST merge via PR with CI checks
• MUST delete branches after merge

Workflow:

git switch -c feat/add-login
# ... make changes ...
git push -u origin feat/add-login
gh pr create --base main
# After approval:
gh pr merge --squash --delete-branch

GitHub Flow

main ─────●─────●─────●─────●─────●─────
           \       /
            ●─────●
          (feature branch)

Workflow:

1. Create branch from main
2. Add commits
3. Open PR
4. Review & discuss
5. Merge to main
6. Deploy

Git Flow (Complex Projects)

main     ─────●───────────────●─────────
              │               │
develop  ─────●─────●─────●───●─────●───
               \   /       \     /
feature         ●─●         \   /
                         release─●

Branches:

• main - production releases
• develop - integration branch
• feature/* - new features
• release/* - release prep
• hotfix/* - production fixes

Common Workflows

Feature Development

# 1. Start fresh
git switch main
git pull

# 2. Create feature branch
git switch -c feat/user-profile

# 3. Work in small commits
git add -p                    # Stage selectively
git commit -m "feat(profile): add avatar upload"
# ... more work ...
git commit -m "feat(profile): add bio field"

# 4. Keep up with main
git fetch origin
git rebase origin/main        # Or merge

# 5. Push and create PR
git push -u origin feat/user-profile
gh pr create --title "feat(profile): add user profile page" --body "$(cat <<'EOF'
## Summary
- Add avatar upload with S3
- Add bio field with markdown support

## Testing
- [ ] Upload various image formats
- [ ] Test bio with special characters
EOF
)"

# 6. After approval
gh pr merge --squash --delete-branch
git switch main
git pull

Hotfix

# 1. Branch from main
git switch main
git pull
git switch -c hotfix/fix-login-crash

# 2. Fix and commit
git commit -m "fix(auth): handle null session token"

# 3. Push immediately
git push -u origin hotfix/fix-login-crash
gh pr create --title "fix(auth): critical login crash" --body "..."

# 4. Fast-track review and merge
gh pr merge --merge --delete-branch

Conflict Resolution

# During merge/rebase, if conflicts occur:

# 1. See conflicted files
git status

# 2. Open conflicted file - look for markers:
# <<<<<<< HEAD
# your changes
# =======
# their changes
# >>>>>>> branch-name

# 3. Edit to resolve (remove markers, keep correct code)

# 4. Mark resolved
git add <resolved-file>

# 5. Continue
git merge --continue          # If merging
git rebase --continue         # If rebasing

# Or abort
git merge --abort
git rebase --abort

Squashing Commits

# Before pushing (interactive rebase)
git rebase -i HEAD~5          # Last 5 commits

# In editor, change 'pick' to 'squash' or 's':
# pick abc1234 First commit
# squash def5678 WIP
# squash ghi9012 More WIP
# squash jkl3456 Fix typo
# squash mno7890 Final touches

# Save, then edit combined commit message

# Alternative: squash merge in PR
gh pr merge --squash

Safety Practices

MUST NOT Do (Without Explicit Permission)

# Force push to shared branches
git push --force origin main     # DANGER
git push --force origin develop  # DANGER

# Hard reset shared branches
git reset --hard origin/main     # On shared branch = DANGER

# Delete remote branches others use
git push origin --delete <shared-branch>

MUST Ask Before

git push --force-with-lease      # Safer force push, but still ask
git rebase                       # On shared branches
git reset --hard                 # Destructive
git clean -fd                    # Removes untracked files

Safe Practices

# SHOULD use --force-with-lease instead of --force
git push --force-with-lease origin feat/my-branch

# MUST check before destructive operations
git status
git log --oneline -5
git diff

# SHOULD stash before switching with changes
git stash
git switch other-branch
git switch -
git stash pop

# MAY use reflog for recovery
git reflog                       # Find lost commits
git reset --hard HEAD@{2}        # Recover

Commit Message Best Practices

MUST

• Use imperative mood: "add feature" not "added feature"
• Keep subject line < 72 characters
• Capitalize first letter of subject
• No period at end of subject
• Separate subject from body with blank line
• Explain "what" and "why" in body, not "how"
• Reference issues: "Closes #123" or "Fixes #456"

MUST NOT

• Use vague messages: "fix bug", "update code", "WIP"
• Combine unrelated changes in one commit
• Include generated files in commits
• Commit secrets, credentials, or .env files

Template

<type>(<scope>): <what changed>

<why this change was needed>

<any additional context>

<footer: issues, breaking changes>

Git Configuration

Recommended Settings

# Identity
git config --global user.name "Your Name"
git config --global user.email "you@example.com"

# Editor
git config --global core.editor "code --wait"

# Default branch
git config --global init.defaultBranch main

# Pull strategy
git config --global pull.rebase true

# Push default
git config --global push.default current

# Aliases
git config --global alias.co checkout
git config --global alias.br branch
git config --global alias.ci commit
git config --global alias.st status
git config --global alias.lg "log --oneline --graph --decorate"

Useful Aliases

# Add to ~/.gitconfig [alias] section:
[alias]
    # Short status
    s = status -sb
    
    # Pretty log
    lg = log --graph --pretty=format:'%Cred%h%Creset -%C(yellow)%d%Creset %s %Cgreen(%cr) %C(bold blue)<%an>%Creset' --abbrev-commit
    
    # Last commit
    last = log -1 HEAD --stat
    
    # Undo last commit (keep changes)
    undo = reset --soft HEAD~1
    
    # Amend without editing message
    amend = commit --amend --no-edit
    
    # List branches by recent
    recent = branch --sort=-committerdate --format='%(committerdate:relative)%09%(refname:short)'

Quick Reference

Daily Workflow

# Morning sync
git fetch && git status

# Before starting work
git switch main && git pull
git switch -c feat/new-thing

# During work
git add -p && git commit -m "..."

# Before pushing
git fetch origin
git rebase origin/main

# Push and PR
git push -u origin HEAD
gh pr create

Emergency Commands

# Undo last commit (keep changes)
git reset --soft HEAD~1

# Discard all local changes
git restore . && git clean -fd

# Recover deleted branch
git reflog
git checkout -b recovered-branch <sha>

# Abort everything
git merge --abort
git rebase --abort
git cherry-pick --abort