How to build Drupal project

[Alessio Frabotta]

On my ubuntu machine I want to copy drupal to the public_html folder of my apache installation.

On jenkins I have the following configuration:

#!/bin/bash


echo ""
echo "Switching to project docroot."
cd /var/www/html/example.com/public_html
echo ""
echo "Pulling down the latest code."
git pull origin master
echo ""
echo "Clearing drush caches."
drush cache-clear drush
echo ""
echo "Running database updates."
drush updb -y
echo ""
echo "Importing configuration."
drush config-import -y
echo ""
echo "Clearing caches."
drush cr
echo ""
echo "Deployment complete."

When I launch the build on Jenkins I get the following error:

Pulling down the latest code.
fatal: Not a git repository (or any of the parent directories): .git

What operations should I do to resolve this error?