🚀 Complete Linux, Git & GitHub Reference Guide

A comprehensive, organized reference for command-line tools, version control, and collaboration

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📋 Table of Contents

1. Linux Command Line Essentials
2. Git Version Control
3. GitHub Workflows
4. Quick Reference Cheat Sheet
5. Visual Mind Map

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🐧 Linux Command Line Essentials

📁 File and Directory Operations

Navigation Commands

pwd                    # Print working directory
ls                     # List directory contents
ls -la                 # List with details and hidden files
ls -lh                 # List with human-readable file sizes
cd /path/to/directory  # Change directory
cd ~                   # Go to home directory
cd ..                  # Go up one directory
cd -                   # Go to previous directory

File Creation and Manipulation

touch filename         # Create empty file
mkdir dirname          # Create directory
mkdir -p path/to/dir   # Create nested directories
cp source dest         # Copy file
cp -r source dest      # Copy directory recursively
mv source dest         # Move/rename file or directory
rm filename            # Remove file
rm -r dirname          # Remove directory recursively
rm -rf dirname         # Force remove directory
rmdir dirname          # Remove empty directory

File Content Operations

cat filename           # Display file content
head filename          # Show first 10 lines
head -n 20 filename    # Show first 20 lines
tail filename          # Show last 10 lines
tail -f filename       # Follow file changes in real-time
less filename          # View file with pagination
more filename          # View file page by page
wc filename            # Word, line, character count
wc -l filename         # Line count only

🔍 Search and Text Processing

Finding Files and Content

find /path -name "pattern"     # Find files by name
find . -type f -name "*.txt"   # Find all .txt files
find . -type d -name "docs"    # Find directories named "docs"
locate filename                # Quick file location search
which command                  # Find command location
whereis command                # Find command and manual pages

Text Search and Processing

grep "pattern" filename        # Search for pattern in file
grep -r "pattern" directory    # Recursive search in directory
grep -i "pattern" filename     # Case-insensitive search
grep -n "pattern" filename     # Show line numbers
grep -v "pattern" filename     # Show lines NOT matching pattern
awk '{print $1}' filename      # Print first column
sed 's/old/new/g' filename     # Replace text
sort filename                  # Sort file contents
uniq filename                  # Remove duplicate lines
cut -d',' -f1 filename         # Extract first column (CSV)

🔐 Permissions and User Management

File Permissions

chmod 755 filename             # Set permissions (rwxr-xr-x)
chmod +x filename              # Add execute permission
chmod u+w filename             # Add write permission for user
chmod g-r filename             # Remove read permission for group
chmod o+r filename             # Add read permission for others
chown user:group filename      # Change file ownership
chown -R user:group directory  # Change ownership recursively

Permission Values

Permission	Binary	Decimal
---	000	0
--x	001	1
-w-	010	2
-wx	011	3
r--	100	4
r-x	101	5
rw-	110	6
rwx	111	7

User Information

whoami                         # Current username
id                             # User and group IDs
groups                         # User's groups
w                              # Who is logged in
last                           # Last login history
su username                    # Switch user
sudo command                   # Run command as superuser

⚙️ System Information and Process Management

System Information

uname -a                       # System information
lsb_release -a                 # Linux distribution info
df -h                          # Disk space usage
du -sh directory               # Directory size
free -h                        # Memory usage
uptime                         # System uptime
date                           # Current date and time
cal                            # Calendar

Process Management

ps aux                         # List all processes
ps aux | grep process_name     # Find specific process
top                            # Real-time process monitor
htop                           # Enhanced process monitor
kill PID                       # Kill process by PID
killall process_name           # Kill process by name
jobs                           # List active jobs
bg                             # Send job to background
fg                             # Bring job to foreground
nohup command &                # Run command immune to hangups

Network Commands

ping hostname                  # Test network connectivity
wget URL                       # Download file from web
curl URL                       # Transfer data from/to server
ssh user@hostname              # Secure shell login
scp file user@host:/path       # Secure copy over network
netstat -tulpn                 # Network connections

🎯 Git Version Control

🏁 Git Setup and Configuration

Initial Setup

# Set up user identity
git config --global user.name "Your Name"
git config --global user.email "your.email@example.com"

# Set default editor
git config --global core.editor "nano"  # or vim, code, etc.

# View all configurations
git config --list

# View specific configuration
git config user.name

Repository Initialization

git init                       # Initialize new repository
git clone <repository-url>     # Clone existing repository
git clone <url> <folder-name>  # Clone to specific folder

📦 Basic Git Workflow

Staging and Committing

# Check status
git status                     # Check repository status
git status -s                  # Short status format

# Add files to staging
git add filename               # Add specific file
git add .                      # Add all files in current directory
git add -A                     # Add all files (including deletions)
git add *.txt                  # Add all .txt files

# Commit changes
git commit -m "Commit message" # Commit with message
git commit -am "Message"       # Add and commit tracked files
git commit                     # Open editor for commit message
git commit --amend             # Modify last commit

Viewing Changes and History

# View differences
git diff                       # Show unstaged changes
git diff --staged              # Show staged changes
git diff HEAD~1                # Compare with previous commit
git diff commit1..commit2      # Compare two commits

# View commit history
git log                        # Show commit history
git log --oneline              # Compact log format
git log --graph                # Show branch graph
git log --oneline --decorate --graph --all  # Detailed graph
git show <commit-hash>         # Show specific commit details

File Operations

git ls-files                   # List tracked files
git rm filename                # Remove file from git and filesystem
git rm --cached filename       # Remove from git but keep file
git mv oldname newname         # Rename/move file

🌿 Branching and Merging

Branch Management

# Create and manage branches
git branch                     # List local branches
git branch -a                  # List all branches (local + remote)
git branch branch-name         # Create new branch
git branch -d branch-name      # Delete branch (safe)
git branch -D branch-name      # Force delete branch
git branch -m old-name new-name # Rename branch

# Switch branches
git switch branch-name         # Switch to branch (Git 2.23+)
git checkout branch-name       # Switch to branch (older method)
git checkout -b branch-name    # Create and switch to branch
git switch -c branch-name      # Create and switch to branch (Git 2.23+)

Merging

# Merge branches
git merge branch-name          # Merge branch into current branch
git merge --no-ff branch-name  # Force merge commit
git merge --squash branch-name # Squash merge

# Check merge status
git branch --merged            # Show merged branches
git branch --no-merged         # Show unmerged branches

Rebasing

git rebase branch-name         # Rebase current branch onto branch-name
git rebase -i HEAD~3           # Interactive rebase (last 3 commits)
git rebase --continue          # Continue rebase after resolving conflicts
git rebase --abort             # Abort rebase operation

🔄 Undoing Changes

Unstaging and Reverting

# Unstage files
git reset filename             # Unstage specific file
git reset                      # Unstage all files
git reset --hard               # Reset to last commit (lose changes)
git reset --soft HEAD~1        # Undo last commit, keep changes staged
git reset --mixed HEAD~1       # Undo last commit, unstage changes
git reset --hard HEAD~1        # Undo last commit, lose changes

# Revert commits
git revert commit-hash         # Create new commit that undoes changes
git revert HEAD                # Revert last commit

# Restore files
git restore filename           # Restore file to last committed state
git restore --staged filename  # Unstage file (Git 2.23+)
git checkout -- filename      # Restore file (older method)

Stashing Changes

git stash                      # Stash current changes
git stash push -m "message"    # Stash with message
git stash list                 # List all stashes
git stash pop                  # Apply and remove latest stash
git stash apply                # Apply latest stash without removing
git stash apply stash@{2}      # Apply specific stash
git stash drop stash@{2}       # Delete specific stash
git stash clear                # Delete all stashes

🐙 GitHub Workflows

🌐 Remote Repository Management

Working with Remotes

# View remotes
git remote                     # List remote names
git remote -v                  # List remotes with URLs
git remote show origin         # Show remote details

# Add and manage remotes
git remote add origin <url>    # Add remote repository
git remote rename origin upstream # Rename remote
git remote remove origin       # Remove remote
git remote set-url origin <new-url> # Change remote URL

Push and Pull Operations

# Push changes
git push origin branch-name    # Push branch to remote
git push -u origin branch-name # Push and set upstream
git push --all origin          # Push all branches
git push --tags                # Push all tags
git push --force               # Force push (dangerous!)
git push --force-with-lease    # Safer force push

# Pull changes
git pull                       # Fetch and merge from upstream
git pull origin branch-name    # Pull specific branch
git pull --rebase              # Pull with rebase instead of merge

# Fetch changes
git fetch                      # Download objects and refs
git fetch origin               # Fetch from specific remote
git fetch --all                # Fetch from all remotes

🏷️ Tags and Releases

Tagging

# Create tags
git tag v1.0.0                 # Create lightweight tag
git tag -a v1.0.0 -m "Version 1.0.0" # Create annotated tag
git tag -a v1.0.0 commit-hash  # Tag specific commit

# List and manage tags
git tag                        # List all tags
git tag -l "v1.*"              # List tags matching pattern
git show v1.0.0                # Show tag details
git tag -d v1.0.0              # Delete local tag
git push origin --delete v1.0.0 # Delete remote tag

# Push tags
git push origin v1.0.0         # Push specific tag
git push origin --tags         # Push all tags

GitHub Specific Operations

# Fork workflow
git remote add upstream <original-repo-url>
git fetch upstream
git checkout main
git merge upstream/main

# Branch management for PRs
git checkout -b feature/new-feature
# Make changes, commit
git push -u origin feature/new-feature
# Create PR on GitHub
# After PR merge:
git checkout main
git pull origin main
git branch -d feature/new-feature
git push origin --delete feature/new-feature

🔧 Advanced Git Features

Git Aliases

# Create useful aliases
git config --global alias.st status
git config --global alias.co checkout
git config --global alias.br branch
git config --global alias.ci commit
git config --global alias.unstage 'reset HEAD --'
git config --global alias.last 'log -1 HEAD'
git config --global alias.graph 'log --oneline --decorate --graph --all'

# Usage: git st instead of git status

Git Hooks

# Hook locations
ls .git/hooks/                 # View available hooks

# Common hooks:
# - pre-commit: Run before commit
# - post-commit: Run after commit
# - pre-push: Run before push
# - post-receive: Run after receiving push

Submodules

# Add submodule
git submodule add <repository-url> <path>

# Initialize and update submodules
git submodule init
git submodule update
git submodule update --recursive

# Clone repository with submodules
git clone --recursive <repository-url>

📄 Quick Reference Cheat Sheet

🚀 Most Used Commands

Category	Command	Description
Linux Basics	pwd	Show current directory
	ls -la	List files with details
	cd directory	Change directory
	mkdir dirname	Create directory
	rm -rf dirname	Remove directory
	chmod 755 file	Set file permissions
Git Basics	git status	Check repository status
	git add .	Stage all changes
	git commit -m "msg"	Commit with message
	git push origin main	Push to remote
	git pull	Pull latest changes
Git Branching	git branch	List branches
	git switch -c branch	Create and switch branch
	git merge branch	Merge branch
	git branch -d branch	Delete branch
Git Undo	git reset filename	Unstage file
	git restore filename	Restore file
	git revert HEAD	Revert last commit
	git stash	Temporarily save changes

🎯 Git Workflow Pattern

# 1. Start new feature
git switch -c feature/new-feature

# 2. Make changes and commit
git add .
git commit -m "Add new feature"

# 3. Push to remote
git push -u origin feature/new-feature

# 4. Create Pull Request on GitHub

# 5. After merge, cleanup
git switch main
git pull origin main
git branch -d feature/new-feature

🧠 Visual Mind Map

🌳 Linux, Git & GitHub Knowledge Tree

📚 LINUX, GIT & GITHUB MASTERY
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├── 🐧 LINUX COMMAND LINE
│   ├── 📁 File Operations
│   │   ├── Navigation      (pwd, ls, cd)
│   │   ├── Creation        (touch, mkdir)
│   │   ├── Manipulation    (cp, mv, rm)
│   │   └── Content         (cat, head, tail, less)
|   |
│   ├── 🔍 Search & Text
│   │   ├── Find Files      (find, locate, which)
│   │   ├── Search Content  (grep, awk, sed)
│   │   └── Process Text    (sort, uniq, cut)
|   |
│   ├── 🔐 Permissions
│   │   ├── File Permission (chmod)
│   │   ├── Ownership       (chown)
│   │   └── User Management (whoami, su, sudo)
|   |
│   └── ⚙️ System
│       ├── Info            (uname, df, free, uptime)
│       ├── Processes       (ps, top, kill)
│       └── Network         (ping, wget, ssh)
│
├── 🎯 GIT VERSION CONTROL
│   ├── 🏁 Setup
│   │   ├── Config          (git config)
│   │   ├── Init            (git init)
│   │   └── Clone           (git clone)
|   |
│   ├── 📦 Basic Workflow
│   │   ├── Status          (git status)
│   │   ├── Staging         (git add)
│   │   ├── Committing      (git commit)
│   │   └── History         (git log, git diff)
|   |
│   ├── 🌿 Branching
│   │   ├── Create          (git branch, git switch)
│   │   ├── Merge           (git merge)
│   │   ├── Rebase          (git rebase)
│   │   └── Delete          (git branch -d)
|   |
│   ├── 🔄 Undoing
│   │   ├── Reset           (git reset)
│   │   ├── Revert          (git revert)
│   │   ├── Restore         (git restore)
│   │   └── Stash           (git stash)
|   |
│   └── 🔧 Advanced
│       ├── Aliases
│       ├── Hooks
│       └── Submodules
│
└── 🐙 GITHUB WORKFLOWS
    ├── 🌐 Remotes
    │   ├── Add/Manage (git remote)
    │   ├── Push            (git push)
    │   ├── Pull            (git pull)
    │   └── Fetch           (git fetch)
    |   
    ├── 🏷️ Tags & Releases
    │   ├── Create Tags     (git tag)
    │   ├── Push Tags
    │   └── GitHub Releases
    |   
    └── 🔄 Collaboration
        ├── Fork Workflow
        ├── Pull Requests
        ├── Code Review
        └── Issue Tracking

🛤️ Learning Roadmap

🎯 Beginner Path (1-2 weeks)

1. Linux Basics

   • Master navigation (pwd, ls, cd)
   • Learn file operations (touch, mkdir, cp, mv, rm)
   • Understand basic permissions (chmod, chown)

2. Git Fundamentals

   • Setup Git (git config)
   • Learn basic workflow (init, add, commit, status)
   • Understand history (git log, git diff)

3. GitHub Basics

   • Create account and first repository
   • Learn push/pull (git push, git pull)
   • Clone existing repositories

🚀 Intermediate Path (2-4 weeks)

1. Advanced Linux

   • Master text processing (grep, awk, sed)
   • Learn system monitoring (ps, top, netstat)
   • Understand pipes and redirection

2. Git Branching

   • Create and switch branches (git branch, git switch)
   • Merge strategies (git merge, git rebase)
   • Resolve conflicts

3. GitHub Collaboration

   • Fork repositories
   • Create Pull Requests
   • Code review process

🏆 Advanced Path (1-2 months)

1. Linux Mastery

   • Shell scripting
   • Process management
   • Network troubleshooting

2. Git Advanced

   • Interactive rebase
   • Git hooks
   • Submodules

3. GitHub Enterprise

   • GitHub Actions (CI/CD)
   • Issue tracking
   • Project management

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💡 Pro Tips

🔥 Linux Power Tips

• Use history | grep command to find previously used commands
• Create aliases for frequently used commands: alias ll='ls -la'
• Use ctrl+r for reverse search in command history
• Master tab completion for faster typing

⚡ Git Power Tips

• Use git commit --amend to fix the last commit message
• Create meaningful commit messages (what and why)
• Use git stash when switching contexts quickly
• Set up aliases for commonly used Git commands

🌟 GitHub Power Tips

• Use issue templates for consistent reporting
• Set up branch protection rules
• Use GitHub CLI (gh) for command-line GitHub operations
• Enable GitHub Pages for project documentation

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📚 Additional Resources

• Git Official Documentation
• GitHub Docs
• Linux Command Reference
• Interactive Git Tutorial

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🎉 Happy Learning! Remember: Practice makes perfect. Start with the basics and gradually build up your skills.