Git & GitHub Reference

Core concepts

• Git: version control system running on your machine.
• GitHub: remote platform for hosting Git repositories.
• Repository: project folder tracked by Git.
• Commit: snapshot of changes.
• Branch: parallel line of development.
• Remote: external repository (usually called origin).

Initial configuration (run once)

Set your identity for commits:

git config --global user.name "Your Name"
git config --global user.email "[email protected]"

Set default main branch:

git config --global init.defaultBranch main

Create or clone repositories

Initialize an existing project

git init

Creates a new Git repository in the current directory.

Clone from GitHub

git clone https://github.com/username/repository.git

Downloads a remote repository.

Status and history

git status

Shows modified files, staged files, and untracked files.

git log

Full commit history.

git log --oneline --graph --decorate

Compact history with branch visualization.

Staging and committing changes

Stage files

git add file.txt

Adds a file to the staging area.

git add .

Stages all changes.

Create a commit

git commit -m "Clear and meaningful message"

Saves staged changes into the repository history.

Tip: Keep commits small and messages descriptive.

Branches

git branch

Lists local branches.

git branch feature-name

Creates a new branch.

git checkout feature-name

Switches to another branch.

git checkout -b feature-name

Creates and switches to a new branch.

git merge feature-name

Merges a branch into the current one.

# Rename current branch
git branch -m new-name

# Delete local branch
git branch -d branch-name

# Delete remote branch
git push origin --delete branch-name

Remotes (GitHub)

git remote -v

Displays configured remotes.

git remote add origin https://github.com/username/repo.git

Links your local repo to GitHub.

git remote set-url origin https://github.com/username/new-repo.git

Push changes

git push

Uploads commits to the tracked remote branch.

git push origin main

Pushes the main branch.

git push -u origin feature-name

Pushes a new branch and sets upstream tracking.

Fetch vs Pull

git fetch

Downloads changes without merging.

git pull

Downloads and merges changes into the current branch.

Rule of thumb: fetch to inspect, pull to apply.

Diff and review

git diff

Shows unstaged differences.

git diff --staged

Shows staged differences.

Undoing changes (careful)

git restore file.txt

Discards local changes in a file.

git reset HEAD file.txt

Removes file from staging area.

git reset --hard

DANGER: Deletes all uncommitted local changes.

git revert <commit-hash>

Stash (temporary save)

git stash

Saves local changes temporarily.

git stash pop

Restores the last stash.

git stash list
git stash apply

Recommended workflow

git checkout main
git pull

git checkout -b feature-x
git add .
git commit -m "Add feature X"
git push -u origin feature-x

Create a Pull Request on GitHub to merge into main.

Best practices

• Do not work directly on main.
• Pull before starting work.
• Use clear, concise commit messages.
• One feature or fix per branch.

Common emergency commands

git status
git add .
git commit -m "Resolve merge conflicts"