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Git 101
2/22/2025·5 min read·20 views

Introduction to Git

What is Git?

  • A checkpoint system that tracks changes in files.
  • A Version Control System (VCS) created by Linus Torvalds.
  • Runs locally on a machine.

What is GitHub?

  • A cloud-based service for hosting Git repositories.
  • Facilitates collaboration and version control.

Command-Line Interfaces

  • Bash: Unix-based command-line interface (default shell for Linux and macOS).
  • Git Bash: Emulates Bash on Windows for a Unix-like experience.
  • Command Prompt: Default shell for Windows.

Configuring Git

git config --global user.name "Son Dao"
git config --global user.email "sondao@gmail.com"
  • Use --global to apply settings system-wide.
  • Use --local for per-repository configuration.

Basic Unix Commands

ls         # List files
ls -a      # Show hidden files
pwd        # Print working directory
cd <dir>   # Change directory
cd ..      # Move up one directory
mkdir <dir> # Create directory
rm <file>  # Remove file
rm -rf <dir> # Remove directory recursively

Git Workflow

  • Working Directory → git add → Staging Area → git commit → Repository
  • Always run git status to check the state of your repo.
  • Avoid nesting repositories inside each other.

Adding & Committing Changes

git init           # Initialize a new repo
git status        # Check status
git log           # View commit history
git add <file>    # Stage a file
git add .         # Stage all changes
git commit -m "Commit message" # Commit changes

Atomic Commits

  • Each commit should represent a single logical change.
  • Use imperative mood for commit messages: "Fix bug", not "Fixed bug".

Amending Commits

git commit --amend  # Modify last commit message or add files

Working with Branches

git branch             # List branches
git branch <name>      # Create a new branch
git switch <name>      # Switch branches
git switch -c <name>   # Create & switch branch
git switch -           # Switch to last branch
  • HEAD points to the current commit/branch.
  • git commit -a -m "msg" combines add and commit (excludes untracked files).

Undoing Changes & Time Travel

Checkout

git checkout <commit>    # View previous commit
git checkout <branch>    # Switch branches
git checkout -- <file>   # Discard changes to file

Restore (Newer Alternative)

git restore <file>       # Restore to last committed state
git restore --staged <file> # Unstage file

Reset (Moving HEAD)

git reset <commit>        # Reset to commit, keep changes
git reset --hard <commit> # Reset and discard changes

Revert (Safe Alternative)

git revert <commit> # Create a commit that undoes a previous commit

Working with Remote Repositories

git clone <url>                     # Clone repo
git remote -v                        # List remotes
git remote add <name> <url>          # Add a new remote
git remote rename <old> <new>        # Rename remote
git push <remote> <branch>           # Push changes
git push -u origin master            # Set upstream branch

Fetching & Pulling Updates

git fetch <remote>                   # Get latest changes (no merge)
git pull <remote> <branch>            # Fetch and merge

Remote Tracking Branches

  • origin/master tracks the remote master branch.
  • git switch <remote-branch> creates a local branch from a remote branch.

Git Workflows

Centralized Workflow

  • Everyone works directly on main.

Feature Branch Workflow

  • Developers work on separate branches, then merge into main.

Fork & Clone Workflow

  • Each developer maintains their own repository.

Merging & Rebasing

Merge (Default Method)

git merge <branch>

Rebase (Alternative to Merge)

git rebase <branch>
  • Moves branch commits to start at the latest main.
  • Do not rebase commits that have been pushed to a shared repository.

Interactive Rebase

git rebase -i HEAD~4  # Modify last 4 commits

Stashing (Saving Temporary Work)

git stash             # Save uncommitted changes temporarily
git stash list        # Show list of stashed changes
git stash apply       # Apply the most recent stash
git stash pop         # Apply and remove the most recent stash
git stash drop        # Delete the most recent stash
git stash clear       # Remove all stashes

Cherry-Picking (Picking Specific Commits)

git cherry-pick <commit-hash>

Diff (Comparing Changes)

git diff                  # Show unstaged changes
git diff --staged         # Show staged changes
git diff <commit1> <commit2> # Compare two commits

Blame (Tracking Who Changed What)

git blame <file>

Clean (Removing Untracked Files)

git clean -n   # Show untracked files to delete
git clean -f   # Force delete untracked files
git clean -fd  # Remove both untracked files and directories

Reflog (History of HEAD Movements)

git reflog               # View history of HEAD changes
git reset --hard HEAD@{n}  # Restore repo to a previous state

Squashing Commits (Combining Multiple Commits)

git rebase -i HEAD~3  # Squash last 3 commits interactively

Git Tags

git tag                    # List tags
git tag -l "*beta*"         # Filter tags