GitHub has become the go-to platform for version control and collaboration on software projects. Whether you are a beginner or an experienced developer, mastering GitHub is essential. This guide will cover the fundamental concepts and commands you need to become proficient with GitHub.

1. Introduction to Git and GitHub

Git is a distributed version control system that tracks changes in source code during software development. It allows multiple developers to work on a project simultaneously without overwriting each other's work.

GitHub is a web-based platform that uses Git for version control and provides a collaborative environment for developers to work on projects together.

Key Concepts

• Repository: A directory that contains your project's files and the entire revision history.

• Commit: A snapshot of changes made to the repository.

• Branch: A parallel version of the repository that diverges from the main line of development.

• Merge: The process of combining changes from different branches.

2. Setting Up Git and GitHub

Install Git

• Windows: Download the installer from git-scm.com and follow the setup instructions.

• macOS: Use Homebrew: brew install git.

• Linux: Use the package manager: sudo apt-get install git.

Configure Git

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

Create a GitHub Account

Sign up for an account at github.com.

Set Up SSH Key (Optional)

This step allows you to interact with GitHub securely.

ssh-keygen -t rsa -b 4096 -C "your.email@example.com"

Add the generated SSH key to your GitHub account.

3. Basic Git Commands

Initializing a Repository

• Purpose: Initializes a new Git repository in your project directory.

• Usage: Run this command in the root directory of your project to start versioning your files.

git init

Cloning a Repository

• Purpose: Creates a local copy of a remote repository.

• Usage: Use this command to download an existing repository from a URL (e.g., GitHub) to your local machine.

git clone <repository-url>

Adding Files

• Purpose: Stages changes for the next commit.

• Usage: git add <file> stages a specific file, while git add . stages all changes in the current directory.

git add <file>
git add .

Committing Changes

• Purpose: Records changes to the repository with a descriptive message.

• Usage: After staging changes, use this command to commit them. The message should describe what changes were made.

git commit -m "Commit message"

Checking Status

• Purpose: Displays the state of the working directory and the staging area.

• Usage: Use this command to see which changes have been staged, which haven’t, and which files aren’t being tracked by Git.

git status

Viewing Commit History

• Purpose: Shows the commit history for the repository.

• Usage: Use this command to view the list of commits made to the repository.

git log

Pushing Changes

• Purpose: Uploads local branch commits to the remote repository.

• Usage: Use this command to push your changes to a specific branch on the remote repository.

git push origin <branch>

Pulling Changes

• Purpose: Fetches and merges changes from the remote repository to your local branch.

• Usage: Use this command to update your local branch with the latest changes from the remote repository.

git pull origin <branch>

4. Branching and Merging

Creating a Branch

• Purpose: Creates a new branch.

• Usage: Use this command to create a new branch for developing new features or fixes.

git branch <branch-name>

Switching to a Branch (If branch already exists)

• Purpose: Switches to the specified branch.

• Usage: Use this command to change your working directory to the specified branch.

git checkout <branch-name>

Creating and Switching to a Branch (If branch doesn't exists)

• Purpose: Creates a new branch and switches to it.

• Usage: Use this command to create and move to a new branch in one step.

git checkout -b <branch-name>

Merging Branches

• Purpose: Combines changes from the source branch into the current branch.

• Usage: Use this command after switching to the target branch to merge changes from another branch.

git checkout <target-branch>
git merge <source-branch>

Deleting a Branch

• Purpose: Combines changes from the source branch into the current branch.

• Usage: Use this command after switching to the target branch to merge changes from another branch.

git branch -d <branch-name>

5. Collaboration on GitHub

Forking a Repository

• Purpose: Creates a personal copy of someone else's repository on GitHub.

• Usage: Use the "Fork" button on GitHub to create your own copy of the repository.

How to Fork a Repository?

1. Navigate to the repository on GitHub.

2. Click the "Fork" button.

Pull Request

• Purpose: Proposes changes you've made to be merged into another repository.

• Usage: Use GitHub's interface to compare your branch and submit a pull request to the original repository.

How to create a pull request?

1. Push your changes to your forked repository.

2. Go to the original repository on GitHub.

3. Click "Compare & pull request".

4. Add a description and submit the pull request.

Reviewing and Merging Pull Requests

1. Go to the "Pull Requests" tab in the repository.

2. Review the changes.

3. Click "Merge pull request".

6. Advanced Git Commands

Stashing Changes

• Purpose: Temporarily saves changes that are not ready to be committed.

• Usage: Use this command to save your changes and clean your working directory without committing.

git stash

Applying Stashed Changes

• Purpose: Restores the most recently stashed changes.

• Usage: Use this command to apply stashed changes back to your working directory.

git stash apply

Viewing Stashes

• Purpose: Lists all stashed changes.

• Usage: Use this command to view the list of stashes you have saved.

git stash list

Rebasing Branches

• Purpose: Reapplies commits on top of another base tip.

• Usage: Use this command to move or combine a sequence of commits to a new base commit.

git checkout <feature-branch>
git rebase <main-branch>

Cherry-Picking Commits

• Purpose: Applies the changes from a specific commit to the current branch.

• Usage: Use this command to apply changes from one commit to another branch.

git cherry-pick <commit-hash>

Resetting to a Previous Commit

• Purpose: Resets the current branch to the specified commit, discarding all changes after that commit.

• Usage: Use this command to revert your branch to a previous state, losing all changes made after the specified commit.

git reset --hard <commit-hash>

7. Best Practices

• Commit Often: Make frequent commits with meaningful messages.

• Use Branches: Create branches for new features and bug fixes.

• Pull Regularly: Regularly pull changes from the main branch to stay up-to-date.

• Review Code: Review and test changes before merging pull requests.

• Write Good Commit Messages: Clearly describe what changes were made and why.

8. Extras

• Purpose: Sets the name that will be attached to your commits.

• Usage: Use this command to configure your Git identity.

git config --global user.name "Your Name"

• Purpose: Sets the email that will be attached to your commits.

• Usage: Use this command to configure your Git email.

git config --global user.email "your.email@example.com"