In systems such as Debian, there is a file
/etc/adduser.conf which includes directive NAME_REGEX that can be used to define which characters are allowed in a username.
Is there a way to do this in CentOS 6.9? I can see that there is a file
/etc/default/useradd but there is no indication anywhere in the documentation that it could support a similar directive.
I would like to be able to create a username with the
@ sign in it, such as