Git and Version Control

Working Code

Example 1: Checking your Git installation and configuration

Check if Git is installed:

git --version

Expected output:

git version 2.43.0

Any version 2.x or higher will work. If Git is not installed:

# macOS
brew install git

# Verify
git --version

Initial setup (one-time only, applies to all projects):

git config --global user.name "John Doe"
git config --global user.email "john@example.com"

Example 2: Creating your first repository

mkdir my-project
cd my-project
git init

Output:

Initialized empty Git repository in /Users/dale/my-project/.git/

Example 3: Checking status with git status

git status

Output:

On branch main

No commits yet

nothing to commit (create/copy files and use "git add" to track)

Create a file and check again:

echo "# My First Project" > README.md
git status

Output:

On branch main

No commits yet

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	README.md

nothing added to commit but untracked files present

Untracked files are files Git is not yet tracking. They appear in red.

Try It Yourself

git status color meanings

git status

Output colors:

• Red: Untracked or modified but not staged
• Green: Staged files (waiting to be committed)

# Add files
echo "First file" > file1.txt
echo "Second file" > file2.txt
git status

Output:

Untracked files:
  (use "git add <file>..." to include in what will be committed)
	README.md
	file1.txt
	file2.txt

# Stage one file
git add README.md
git status

Output:

Changes to be committed:
  (use "git restore --staged <file>..." to unstage)
	new file:   README.md    <- green

Untracked files:
	file1.txt                <- red
	file2.txt

What is HEAD?

HEAD is a pointer to your current working position.

Commit A -> Commit B -> Commit C
                            ^
                           HEAD (current position)

Right now there are no commits, so HEAD has nothing to point to. It becomes active after the first commit.

"Why?" -- What if there were no version control?

Without version control, you end up with problems like these:

• project_final.zip, project_final_v2.zip, project_final_REALLY_FINAL.zip
• "It worked yesterday but broke today" -- no idea what changed
• A teammate edits the same file and someone's work gets overwritten

Git solves all of these:

Git's three areas

Working Directory -> (git add) -> Staging Area -> (git commit) -> Repository

• Working Directory: Where your actual files live
• Staging Area: A holding area for changes to include in the next commit
• Repository: Where commit history is stored (the .git directory)

Common Mistakes

Mistake 1: Forgetting git config

git commit   # Without setting up identity
# Author identity unknown
# Please tell me who you are.

Set your name and email first:

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

Mistake 2: Running git init inside a nested directory

cd ~/projects/myapp
git init

# Accidentally running it again in a subdirectory
cd src
git init   # Creates a nested repository

Run git init only once, at the project root.

Mistake 3: Deleting the .git directory

# Never do this!
rm -rf .git   # All Git history is gone

The .git directory is Git's database. Deleting it is irreversible.

Deep Dive

git config --list

user.name=John Doe
user.email=john@example.com
core.editor=vim

git config user.name
# John Doe

# View the global config file directly
cat ~/.gitconfig

# Use a different email for a specific project
git config user.email "work@company.com"  # Without --global, it's project-specific

ls .git/

HEAD        config      description hooks/      info/       objects/    refs/

# Set default branch name for new repositories
git config --global init.defaultBranch main

# Rename master to main
git branch -m master main