Follow below steps for Upgrade Magento 2.1.9 To 2.2.0 or any new Version Using CLI. Replace 2.2.0 with the Magento version you want to upgrade.
- composer require magento/product-community-edition 2.2.2 --no-update
- composer update
- php bin/magento setup:upgrade
- php bin/magento cache:clean
- php bin/magento cache:flush
Hope this we'll helps you on magento upgradetion.