How to create a backend (administrative) account from the command line?

Use admin:user:create console command:

bin/magento admin:user:create --admin-user="Dmitry Fedyuk" --admin-password="Za1112Uj" --admin-email="admin@mage2.pro" --admin-firstname="Dmitry" --admin-lastname="Fedyuk"

Key phrases: “add administrator”, “register administrator”, “create administrator”.

See also:

• The list of the Magento 2 embedded console commands