# Teleport instantly to your user's home directory
cd ~
 
# Verify your active Git installation and version
git --version
 
# Configure your master Git user credentials (if not already set)
git config --global user.name "Platform Engineer Lab"
git config --global user.email "lab@ai-platform.internal"
 
# Configure your master Git preferences for clean rebasing and diff3 conflicts
git config --global pull.rebase true
git config --global merge.conflictstyle diff3

# Create a brand-new lab directory named 'git-mastery-lab' and navigate into it
mkdir -p ~/git-mastery-lab && cd ~/git-mastery-lab
 
# Initialize a fresh Git repository
git init
 
# Create a base configuration file and stage it to generate a Blob object
echo "server_port = 8080" > config.toml
git add config.toml
 
# Commit the file to generate your Tree and Commit objects
git commit -m "chore: initial base commit"
 
# Inspect the active Git HEAD pointer file
cat .git/HEAD
 
# Inspect the raw plain-text content of your active HEAD commit object
git cat-file -p HEAD
 
# Inspect the raw plain-text table of the root tree object referenced in the commit
git cat-file -p HEAD^{tree}

# Create and instantly switch to a brand-new feature branch
git switch -c feature/add-database
 
# Create three separate messy work-in-progress commits
echo "db_host = 'localhost'" >> config.toml
git commit -am "wip: add db host"
 
echo "db_port = 5432" >> config.toml
git commit -am "wip: add db port"
 
echo "db_name = 'production_ai'" >> config.toml
git commit -am "wip: add db name"
 
# Inspect your messy 4-commit history graph
git log --graph --oneline
 
# Simulate an interactive squash of the last 3 commits into a single atomic commit
# (In an automated lab script, we use git reset to elegantly simulate the squash)
git reset --soft HEAD~3
git commit -m "feat(database): configure production database connection parameters"
 
# Verify that your 3 messy commits were successfully squashed into a single atomic commit!
git log --graph --oneline

# Jump back to the master main branch
git switch main
 
# Modify the server_port on line 1 to 9090 and commit
echo "server_port = 9090" > config.toml
git commit -am "fix: update server port to 9090 on main"
 
# Switch back to your feature branch
git switch feature/add-database
 
# Modify the server_port on line 1 to 7070 and commit
sed -i 's/server_port = 8080/server_port = 7070/g' config.toml
git commit -am "fix: update server port to 7070 on feature"
 
# Attempt to rebase your feature branch onto main to force a direct text collision!
git rebase main 2>/dev/null || true
 
# Inspect the active repository state to view your unmerged conflicting files
git status
 
# Inspect the raw plain-text content of config.toml to view your conflict markers!
cat config.toml
 
# Manually resolve the conflict by overwriting the file with clean, resolved text
echo -e "server_port = 9090\ndb_host = 'localhost'\ndb_port = 5432\ndb_name = 'production_ai'" > config.toml
 
# Mark the conflict as successfully resolved in the Git Index
git add config.toml
 
# Resume and complete the rebase operation
git rebase --continue 2>/dev/null || true
 
# Verify your pristine, perfectly linear commit history graph!
git log --graph --oneline

# Create a custom pre-commit hook script to intercept commits containing 'PRIVATE_KEY'
cat << 'EOF' > .git/hooks/pre-commit
#!/bin/bash
echo "--- CUSTOM GIT HOOK: SCANNING FOR SECRETS ---"
if git diff --cached | grep -q "PRIVATE_KEY"; then
    echo "ERROR: Exposed Private Key detected in staged files!"
    echo "Commit forcefully aborted by pre-commit hook!"
    exit 1
fi
exit 0
EOF
 
# Make your custom Git hook script executable
chmod +x .git/hooks/pre-commit
 
# Create a test file containing an exposed private key string and stage it
echo "aws_secret = 'PRIVATE_KEY_987654321'" > secret.toml
git add secret.toml
 
# Attempt to commit the secret file to verify that your hook forcefully aborts the commit!
git commit -m "attempt to commit exposed secret key" 2>/dev/null || true
 
# Verify that the secret file remains uncommitted in your working directory
git status | grep "secret.toml"

# Create a demonstration Git submodule configuration file (.gitmodules)
cat << 'EOF' > .gitmodules
[submodule "modules/aws-vpc"]
	path = modules/aws-vpc
	url = https://github.com/terraform-aws-modules/terraform-aws-vpc.git
EOF
 
# Stage the .gitmodules file and a clean test file
echo "aws_secret = 'CLEAN_KEY_NO_SECRETS'" > secret.toml
git add .gitmodules secret.toml
 
# Commit the clean files to verify that your pre-commit hook successfully passes!
git commit -m "feat(submodule): configure external AWS VPC submodule tracking"
 
# Inspect the final visual commit history graph of your lab repository!
git log --graph --oneline

# Verify the active linear commit history contains your submodule commit
git log --oneline | head -n 1 | grep "feat(submodule)"
 
# Verify the presence and executability of your custom pre-commit hook script
[ -x .git/hooks/pre-commit ] && echo "Git Hook Verified: Executable"
 
# Verify the exact exit code of your most recently executed command
echo "Master Exit Code: $?"

[hash] feat(submodule): configure external AWS VPC submodule tracking
Git Hook Verified: Executable
Master Exit Code: 0

# Jump back to the home directory to ensure a safe starting location
cd ~
 
# Safely remove the demonstration Git mastery lab directory
rm -rf ~/git-mastery-lab 2>/dev/null || true