🧱 Git Fundamentals & Workflow (Deep Dive)

This section explains core Git concepts, commands, and real-time usage with practical examples.

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🧠 Stages of Git (Core Concept)

Working Directory → Staging Area → Local Repository → Remote Repository
     (edit)            (add)            (commit)            (push)

📌 Explanation

Stage	Description
📝 Working Directory	Where you write/edit code
📦 Staging Area	Where changes are prepared (git add)
🗂 Local Repository	Stored in .git folder (commit history)
☁️ Remote Repository	GitHub / remote storage

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⚙️ Setup Git Environment (RHEL / Linux)

sudo -s
mkdir gitproject
cd gitproject

yum install git -y
git --version

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🚀 Initialize Repository

git init

👉 Creates .git directory (stores history + metadata)

git status

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📂 First File Workflow

touch index.html
vi index.html

git status

🔴 Untracked → not added yet

git add index.html

🟢 Tracked (staged)

git commit -m "my first commit"

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🧩 Git Flow Diagram

index.html
   ↓
Working Directory
   ↓ git add
Staging Area
   ↓ git commit
Local Repository (.git)

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📄 Multiple File Commits

touch hello.txt
git add hello.txt
git commit -m "second commit"

touch test.txt
git add test.txt
git commit -m "third commit"

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📌 File Modes in Git

100644 → Normal file
100755 → Executable file

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📜 Git Logs & History

git log
git log --oneline
git log --oneline -2
git log -p -2
git log --stat

Custom Format

git log --pretty=format:"%h - %an, %ar : %s"

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🔍 Inspect Changes

git show
git show <commit-id>

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🧾 Git Blame (Line Tracking)

git blame index.html

👉 Shows who changed each line

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🔄 Git Diff (Compare Changes)

Working vs Staging

git diff

Staging vs Repository

git diff --staged

Working vs Last Commit

git diff HEAD

Between Commits

git diff <commit1>..<commit2>

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🧩 Diff Visual

Working Dir ≠ Staging → git diff
Staging ≠ Repo       → git diff --staged
Working ≠ Repo       → git diff HEAD

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👤 Git User Configuration

git config user.name "your-name"
git config user.email "your-email"

Check:

git config --list

Global config:

git config --global --edit

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🔍 Filter Logs by Author

git log --author="User"

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📦 Add Multiple Files

touch python{1..5}
git add .
git commit -m "multiple files"

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🧠 Important Observations

• .git folder stores entire history
• git add = move to staging
• git commit = save snapshot
• git status = current state
• git diff = compare changes

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🎯 Summary

git init      → initialize repo
git add       → stage changes
git commit    → save snapshot
git log       → view history
git diff      → compare changes
git blame     → track line changes

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⭐ Pro Tips

• Always check git status before commit
• Use git diff to avoid mistakes
• Configure username before committing
• Keep commits small and meaningful

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🚀 Git Learning Notes (Hands-on + Visual Guide)

Welcome to my Git Practical Learning Repository 📘 This guide includes real-world Git commands with clear explanations and diagrams.

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🧠 Git Basics (How Git Works)

Working Directory  →  Staging Area  →  Repository
     (edit)            (git add)         (commit)

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📂 1. Basic Workflow

vi index.html
git add index.html
git commit -m "1st commit"

👉 Repeat changes and commits multiple times to build history.

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✏️ 2. Git Amend (Modify Last Commit)

git commit --amend -m "updated message"

🧩 Diagram

Before:
A → B → C (HEAD)

After:
A → B → C' (HEAD)

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🔁 3. Git Rebase (Modify Multiple Commits)

git rebase -i HEAD~3

• Opens interactive mode
• Replace pick with reword
• Modify commit messages

🧩 Diagram

Before:
A → B → C → D (HEAD)

After:
A → B' → C' → D' (HEAD)

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🧩 4. Squashing Commits

git rebase -i HEAD~3

🧩 Before

A → B → C → D (HEAD)

🧩 After (Squash)

A → B → D' (HEAD)

👉 Multiple commits → One clean commit

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⚠️ 5. Git Reset (Move HEAD)

Soft Reset

git reset --soft HEAD^

A → B → C (HEAD)

After:
A → B (HEAD)
Changes still in staging

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Hard Reset

git reset --hard HEAD^

A → B → C (HEAD)

After:
A → B (HEAD)
Changes ❌ deleted

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🔄 6. Git Checkout (Restore Files)

git show <commit-id>:index.html
git checkout <commit-id> -- index.html

Restore all files:

git checkout <commit-id> -- *

Return to latest:

git checkout master -- index.html

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🆕 7. Git Restore (Modern Alternative)

Undo local changes

git restore file.txt

Unstage file

git restore --staged file.txt

OR

git rm --cached file.txt

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📊 Restore vs Reset

Feature	git restore	git reset
Scope	Working dir / staging	Full repo
Affects history	❌ No	✅ Yes
Use case	Undo changes	Move HEAD
Safety	Safe	Risky

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🧠 8. HEAD Explained

HEAD → current branch → latest commit

Example

HEAD → master → A → B → C

Detached HEAD

HEAD → C
master → B

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📦 9. Git Stash (Temporary Work Save)

Flow Diagram

Working Directory
     ↓
 git stash
     ↓
[ Saved in stash ]
     ↓
Working Directory Clean

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🧪 Real Scenario

Step 1: Work on Story1

vi story1
git add story1
git stash

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Step 2: Work on Story2

vi story2
git add story2
git commit -m "story2"

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Step 3: Restore Story1

git stash apply

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📋 Useful Commands

git stash list
git stash apply
git stash clear

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Stash Specific Files

git stash push -m "message" -- story1 story2

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🧹 10. Cleanup Repo

rm -rf *
git add .
git commit -m "clean"

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🎯 Summary Cheat Sheet

git add        → stage changes
git commit     → save changes
git amend      → fix last commit
git rebase     → edit history
git reset      → move HEAD
git restore    → undo changes
git stash      → temporary save

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⭐ Pro Tips

• ✅ Use git restore instead of checkout
• ⚠️ Avoid git reset --hard unless sure
• 🧠 Understand HEAD before using rebase
• 🚀 Keep commit history clean using squash

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🧑‍💻 Author

Git Practice & Learning Notes Built for DevOps & Interview Preparation 🚀