Ubuntu 사용자 이름 설정
Please enter a username matching the regular expression configured
via the NAME_REGEX[_SYSTEM] configuration variable. Use the `--force-badname'
option to relax this check or reconfigure NAME_REGEX.
The regex error you are seeing is basically saying that the username you tried to set does not meet the "rules" your system has set for what characters can be in usernames. By default, Ubuntu does not allow capital letters in usernames. The username you provided, "Icymoguls," has a capital letter at the beginning and therefore Ubuntu will not accept it.
Ubuntu only accepts usernames based on the following rules:
- Must start with a lowercase letter
- May only contain lowercase letters, underscore (_), and dash (-)
- May optionally end with a dollar sign ($)
A regular expression is merely a string that shows what is and what is not allowed in another string. When creating a new user, Ubuntu checks potential usernames against its builtin regular expression for usernames (which is ^[a-z][-a-z0-9_]*\$ in case you were curious!).