Upgrading to Drush 9
Drush should be installed and updated through composer. There is no stable Drush 9 version yet, so the development version must be used. Updating to the development version of Drush 9 is a simple as typing:
composer require drush/drush:dev-master
Porting your Drush commands to Drush 9
Porting the commands is a semi-automatic process: There is a command that will generate the required files and class structure for you. To start the wizard, just type:
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