🚀 GIT Essentials for Version Control

🎯 Purpose

Git is an open-source version control system that tracks changes to files over time, allowing multiple people to collaborate on a project without overwriting each other’s work.

🌱 Origin

Git has been created by Linus Torvalds, also the creator of the OS Linux. It´s a british slang term meaning a silly/unpleasant person. Torvalds jokingly called himself an “egotistical bastard” who names all his projects after himself. The first stable version was released on December 2005.

🧠 Essentials

⚙️ Ubuntu Installation

sudo apt update; sudo apt install git
git --version

🔁 Git Workflow

• Local vs Remote:
  • Local repo is stored on local computer
  • Remote repo is a copy of the project hosted on a server, used for collaboration and backups.
• Git stages: Edit → add → commit → push
  1. Working directory: make your local changes
  2. Staging area: select which changes to save locally
  3. Repository
  • local repo: save permanently your local changes with a commit
  • remote repo: save permanently your local changes on the remote repo with a push
• Branching:
  • Git branch: separate & independent line of development within a project
  • Allows you to work on new features or bug fixes without affecting the main codebase.
  • Merge after review & finish
• .gitignore Exclude files from version control. e.g. binaries, logs, tmp files…

🔧 Core Commands

• git init → Initialize a local folder as local repository (repo)

• git clone https://github.com/[user]/repo.git → Clone a remote repo to your machine.

• git add . → Stage all changes for commit.

• git commit -m "Add login feature" → Commit staged changes with a message.

• git push origin main → Push local commits to the main branch on remote.

• git fetch origin main → Download latest changes of the branch main from remote repo origin.

• git merge origin/main → merge latest changes of the branch main from remote repo origin to current local branch.

• git pull origin main → Download & merge latest changes of the branch main from remote repo origin to current local branch.

• git status → See which files have changed.

• git log @{u}..HEAD → View all commits on current local branch, that are not yet on its upstream remote branch

• git config --global --list → Display the global git configuration

🌿 Branching

• git checkout -b feature/login → Create & switch to a new feature branch.

• git switch main → Switch back to main branch.

• git merge feature/login → Merge feature branch feature/login into current local branch.

🧼 Undo & Fixes

• git restore index.html → Discard changes in index.html.

• git reset --soft HEAD~1 → Undo last commit but keep the file changes.

🌐 GitHub Integration

• Create local Repo & Push to GitHub Remote Repo

  1. Create local repo: Open terminal in local WS & run git init
  2. Stage Files: Run git add . to stage all files for the first commit.
  3. Set user metadata: (optional, only once)
     • git config --global user.email "you@example.com"
     • git config --global user.name "Your Name"
  4. Commit Changes: Run git commit -m "Initial WoF commit" to save a snapshot of current WS state.
  5. Create Remote Repo:
     • Login in to GitHub
     • Create create a new, empty repo
     • Authenticate (e.g. using build-in VS Code GitHub Extension or using PAT)
  6. Connect local & remote Repos: Run git remote add origin <Github´s remote repo URL>.
  7. Rename local main branch to (main) instead of master: Run git branch -M main
  8. Push to GitHub: Run git push -u origin main to push local files to the remote repo.

• Create a GitHub PAT (Personal Access Token) for Authentication

1. Why PAT instead of Passwords or SSH Keys:

• Granular Permissions
• Revocation & Expiration
• Auto Detection & Revocation on accidental commit
• High Entropy & Uniqueness

2. Log into GitHub & select Profile Picture → Settings → Developer settings → Personal access tokens → Tokens (classic)
3. Click Generate new token & select Generate new token (classic)
4. Configure Token
5. Click on Generate token → Important: Copy and save this now. You won’t be able to see it again..
6. Use PAT in Git CMDs (e.g. while cloning) → When Git asks for credentials: Username → GitHub username; Password → PAT

• Manage Pull Request (PR) via GitHub UI.

👨‍💻VS Code Integration

• VS Code Git Integration in Project Explorer

• GitHub Authentication with Build-In GitHub Extension

• Auto sign in using browser and store login token in VS Code’s storage
• Stores credentials in the OS Keychain using build-in linux app gnome-keyring

• Sign out VS Code from GitHub

1. In the VS Code Activity Bar (left, below), click on → Accounts → (GitHub) → Sign Out
2. Remove credentials from OS Keychain using GUI seahorse of gnome-keyring

• VS Code on Ubuntu uses gnome-keyring to store tokens, if no credential-helper.

# Open GUI
seahorse 
# In the `login` tab, remove entry of application `code`

3. Remove credentials from Git’s own config

git config --global --unset credential.helper
git credential-cache exit # clear any in-memory cache

🔒 **Security

• Git Credential Manager (GCM) is a superior choice for storing credentials:

• Use operating system’s native secure credential storage
• Support for modern Auth Protocols (OAuth, PAT…) & GUI for Login
• Full support of Multi-Factor Auth
• Cross-Platform Consistency

# Option 1 - use git-credential-manager to securely store credentials to OS Keychain
# Download installer and save to 
wget "https://github.com/git-ecosystem/git-credential-manager/releases/download/v2.6.1/gcm-linux_amd64.2.6.1.deb" -O /tmp/gcm.deb 
# Install
sudo dpkg -i /tmp/gcmcore.deb 
# (optinal) Update dependencies if errors occured during installation
sudo apt --fix-broken install -qq
# Configure credentials to be stored securely
git config --global credential.helper manager
git config --global credential.credentialStore secretservice

# Option 2 - store credentials in plain text in file ~/.git-credentials
git config --global credential.helper store`

• Remove credential storage method with following CMD → git config --global --unset credential.helper