Check if script is running as root

upgrades/extras/upgrade_ubuntu_to_20.04/upgrade.sh

@@ -9,7 +9,11 @@ RED='\033[31m'
 NO_COLOR='\033[0m'
 
 ZIP_FILENAME=pnetlabv6_offline.zip
-URL_ZIP_FILE=https://unetlab.cloud/api/raw/?path=/UNETLAB%20I/upgrades_pnetlab/extras/upgrade_to_ubuntu_20.04/pnetlabv6_offline.zip
+# Check if user is root
+if [ "$(id -u)" != "0" ]; then
+    echo -e "${RED}Upgrade has been rejected. You must run this script as root${NO_COLOR}"
+    exit 0
+fi
 
 lsb_release -r -s | grep -q 20.04
 if [ $? -ne 0 ]; then