📘 Git Summary Guide

 📘 Git Summary Guide

I. What is Git?

Git is a distributed version control system used to track changes in source code. It enables multiple developers to collaborate, manage versions, and maintain a history of code changes.

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II. Core Concepts

Concept	Description
Repository	A directory that contains your project and Git metadata.
Commit	A snapshot of changes with a message.
Branch	A movable pointer to a commit; enables isolated development.
Merge	Combines changes from one branch into another.
Clone	Creates a local copy of a remote repository.
Pull	Fetches and merges changes from remote to local.
Push	Sends local commits to the remote repository.

III. Git Architecture

1. Working Directory
   The local directory where you're actively working.

2. Staging Area (Index)
   Temporary area to prepare changes before committing.

3. .git Directory (Repository)
   Internal database storing all history and config for the repo.

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IV. Common Git Commands

A. Setup

bash

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

B. Repository Management

bash

git init                       # Initialize a new repo
git clone <url>                # Clone a repo
git remote add origin <url>    # Add a remote

C. Stage and Commit

bash

git add <file>                # Stage file(s)
git add .                     # Stage all files
git commit -m "Message"       # Commit staged changes

D. Branching

bash

git branch                    # List branches
git branch <name>             # Create branch
git checkout <name>           # Switch branch
git switch <name>             # (Newer alternative)

E. Merging and Rebasing

bash

git merge <branch>            # Merge changes
git rebase <branch>           # Reapply commits on top of another base

F. Synchronizing

bash

git fetch                     # Fetch from remote (no merge)
git pull                      # Fetch + merge
git push                      # Push to remote

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V. Git Branching Model

1. Main/Master – Main production branch.

2. Feature Branches – For developing new features.

3. Develop Branch – Integration branch for features (optional).

4. Release Branch – Used to stabilize a release.

5. Hotfix Branch – Quick fixes to production.

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VI. Undo & Reset

Command	Description
git checkout -- <file>	Discard changes in a file
git reset HEAD <file>	Unstage a file
git revert <commit>	Create a new commit that undoes a previous one
git reset --hard	Reset working dir and index (dangerous)

VII. Tags

Used to mark specific points in history as important (e.g., releases).

bash

git tag v1.0.0
git push origin v1.0.0

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VIII. Git Log and Diff

bash

git log                      # View commit history
git log --oneline --graph    # Compact history
git diff                     # Show file changes
git status                   # See file state

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IX. Git Ignore

Use .gitignore to prevent files from being tracked.

bash

*.log
node_modules/
.env

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X. Git in CI/CD & DevOps

• Git repositories serve as the source of truth for automation (e.g., Jenkins, GitLab CI).

• GitOps is the practice of using Git as the single source of truth for infrastructure and deployments.

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XI. Git Best Practices

1. Use meaningful commit messages.

2. Make small, frequent commits.

3. Use branches for features/fixes.

4. Keep your main branch clean (always deployable).

5. Use Pull Requests/Merge Requests with peer review.

6. Never rebase/push force to shared branches unless coordinated.