if(Mage::isInstalled()){ echo "Magento is installed!"; } else { echo "Magento is not installed!"; }
$package = 'Mage_Catalog'; if(Mage::isInstalled($package)){ echo "The {$package} package is installed!"; } else { echo "The {$package} package is not installed!"; }In this example, the function is used to check whether the Mage_Catalog package is installed or not. If it is installed, it will display "The Mage_Catalog package is installed!" message. In terms of package library, Mage is typically a reference to the Magento core library.