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# Git Reference and Guide
#
# ReferenceCollection.com
# Licensed under CC BY-SA
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# TABLE OF CONTENTS
# -----------------
# 1. Introduction to Git
# 2. Core Concepts and Architecture
# 3. Installation and Basic Setup
# 4. Basic Commands and Workflow
# 5. Branching and Merging
# 6. Remote Operations
# 7. Advanced Git Operations
# 8. Git Workflows
# 9. Hooks and Automation
# 10. Troubleshooting and Maintenance
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# 1. Introduction to Git
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# Git is a free and open source distributed version control system (DVCS). Created
# by Linus Torvalds in 2005, it has become the standard in software development.
# Key Features:
# - Distributed System: Every developer has a full copy of the repository
# - Branching: Lightweight and powerful branching capabilities
# - Data Integrity: SHA-1 hash ensures content integrity
# - Staging Area: Intermediate area between working directory and repository
# - Speed: Most operations are local, making it very fast
# - Free and Open Source: Available under GNU General Public License version 2.0
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# 2. Core Concepts and Architecture
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# Repository Structure:
# - Working Directory: Your active workspace with current files
# - Staging Area (Index): Temporary area where changes are prepared before committing
# - Local Repository (.git): Complete version history stored on your machine
# - Remote Repository: Shared version of the repository hosted on a server
# Key Concepts:
# - Commit: Immutable snapshot of changes at a specific point in time
# - Branch: Independent line of development
# - Tag: Named reference to specific commit (usually versions)
# - Merge: Combining different branches of development
# - Remote: Connection to external repository
# - Fork: Server-side repository copy
# - Clone: Copy of an existing Git repository
# - HEAD: Pointer to the latest commit in current branch
# - HEAD~1: First parent commit
# File States:
# - Untracked: New files Git doesn't track
# - Modified: Changed but not staged
# - Staged: Marked for next commit
# - Committed: Safely stored in Git database
# - Ignored: Files not tracked by Git
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# 3. Installation and Basic Setup
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# Installation Methods:
sudo apt install git # Debian/Ubuntu
sudo yum install git # Red Hat/CentOS
brew install git # macOS
# Windows:
# Download from https://git-scm.com/download/win
# Verify installation:
git --version
# Initial Configuration:
git config --global user.name "username"
git config --global user.email "[email protected]"
# Set default branch name:
git config --global init.defaultBranch main
# Set default editor:
git config --global core.editor "nano"
# Configure line ending behavior:
git config --global core.autocrlf input # On Unix/Mac
git config --global core.autocrlf true # On Windows
# Configuration levels:
# --system: Affects all users on system
# --global: Affects all repositories for current user
# --local: Affects only current repository (default)
# View all configurations:
git config --list
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# 4. Basic Commands and Workflow
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# Repository Creation:
git init # Initialize new repository
git clone <url> # Clone existing repository
git clone <url> <directory> # Clone existing repository into specific folder
# Staging Changes:
git status # Check repository status
git add <file> # Stage specific file
git add . # Stage all changes
git add -p # Interactive staging
# Committing:
git commit -m "message" # Commit with message
git commit -am "message" # Automatically stages changes and commit
git commit --amend # Modify last commit
# History and Differences:
git log # View commit history
git log --oneline # Compact view
git log --graph # Visual representation
git show <commit> # View specific commit
git diff # Show unstaged changes
git diff --staged # Show staged changes
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# 5. Branching and Merging
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# Branch Operations:
git branch # List branches
git branch <name> # Create branch
git checkout <name> # Switch branches
git checkout -b <name> # Create and switch
git switch <branch> # Switch branches (preferred)
git switch -c <branch> # Create and switch (preferred)
git branch -d <name> # Delete branch
git branch -m <name> # Rename branch
# Merging:
git merge <branch> # Merge branch into current
git merge --ff-only <branch> # Fast-forward only
git merge --no-ff --no-commit # Manual merge commit
git merge --abort # Abort troubled merge
git mergetool # Start merge tool
# Conflict Resolution:
# 1. Open conflicted files
# 2. Look for conflict markers (<<<<<<, =======, >>>>>>>)
# 3. Edit files to resolve conflicts
# 4. Stage resolved files
# 5. Complete the merge with commit
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# 6. Remote Operations
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# Remote Management:
git remote -v # List remotes
git remote add <name> <url> # Add remote repository(url)
git remote remove <name> # Remove remote
git remote rename <old> <new> # Rename remote
# Syncing:
git fetch <remote> # Download changes without merging
git pull <remote> <branch> # Pull changes from remote
git push <remote> <branch> # Push changes to remote repository
git push -u origin <branch> # Push to remote repository
# Remote Branches:
git branch -r # List remote branches
git checkout -t origin/<branch> # Track remote branch
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# 7. Advanced Git Operations
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# Stashing:
# Temporarily saves changes that are not yet ready to be committed
git stash # Save changes temporarily
git stash list # List stashes
git stash pop # Apply and remove last stash
git stash apply # Apply and keep last stash
git stash apply stash@{1} # Apply specific stash
git stash drop # Delete last stash
git stash clear # Remove all stashes
# Rebasing:
# Rewrites commit history by moving changes to a new base branch
git rebase <branch> # Rebase current branch
git rebase -i HEAD~3 # Interactive rebase
git rebase --abort # Abort rebase
# Tags:
# Used to mark specific points in Git history, often for releases
git tag # List tags
git tag -a v1.0.0 -m "Version 1.0.0" # Create annotated tag
git tag -d v1.0.0 # Delete tag
git push origin --tags # Push tags to remote
git checkout v1.0.0 # Checkout tag
# Submodules:
# Include other repositories within a Git repository
git submodule add <url> <path> # Add submodule
git submodule init # Initialize submodule
git submodule update # Update submodule
git submodule status # Show submodule status
# Aliases:
# Create shortcuts for frequently used commands
git config --global alias.br branch # Usage: git br
git config --global alias.st status
git config --global alias.ci commit
# Undoing Changes:
# Revert changes made to the repository
git reset --soft HEAD~1 # Undo commit, keep changes
git reset --mixed HEAD~1 # Undo commit and staging
git reset --hard HEAD~1 # Undo commit, discard changes
git revert <commit-hash> # Revert specific commit
git restore --staged filename # Unstage file without losing changes:
git restore filename # Discard local changes to file:
# Advanced Operations:
git cherry-pick <commit> # Apply specific commit
git bisect start # Binary search for bugs
git clean -n # Show what will be cleaned
git clean -f # Remove untracked files
git clean -fd # Remove files and directories
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# 8. Git Workflows
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# Feature Branch Workflow:
# 1. Create feature branch
git checkout -b feature/name
# 2. Stage changes and commit
git add .
git commit -m "Add feature"
# 3. Push to remote
git push origin feature/name
# 4. Create pull request (via web interface)
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# 9. Hooks and Automation
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# Git hooks are scripts that run automatically before or after certain Git commands.
# Hook Locations:
# .git/hooks/pre-push: Run before push
# .git/hooks/pre-commit: Run before commit
# .git/hooks/commit-msg: After commit message is entered
# .git/hooks/post-merge: Run after merge
# .git/hooks/post-checkout: Run after git checkout
# Example pre-commit hook:
cat > .git/hooks/pre-commit << 'EOF'
#!/bin/sh
git diff --cached --name-only | while read file; do
# Add your checks here
echo "Checking $file"
done
EOF
chmod +x .git/hooks/pre-commit
# Common Hook Uses:
# - Unit test execution
# - Commit message validation
# - Preventing sensitive data commits
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# 10. Troubleshooting and Maintenance
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# Repository Health:
git fsck # Check repository integrity
git gc # Clean up repository
git prune # Remove unreachable objects
# Recovery Tools:
git reflog # View reference history
git checkout HEAD@{1} # Go to previous state
git reset --hard ORIG_HEAD # Undo last major change
# Debugging:
git blame <file> # Show who changed what
git bisect start # Binary search for bugs
git verify-pack -v .git/objects/pack/pack-*.idx # Verify objects