Format for admin username

This option determines how the default administrator's username for new servers is created from the domain name. The options are :

Full domain name

The username is always the same as the full domain name, like example.com.

First part of domain

The username is the first part of the domain name like example if available, otherwise the full domain name like example.com.

Same as prefix

The username follows the same rule as the Domain name style in usernames config option above this one.

First part @ domain

The username is always a full email address, like example@example.com

Regular expression custom pattern

The prefix will be automatically generated based on custom regular expression pattern, like u-[0-9]{4} or [a-z]-[0-9]{2} or user-[0-9]{2}-${year}-${month}-${day} which will produce u-1234 or x-89 or user-99-2021-12-25 accordingly.