How to create username with "."

[Miner, Jonathan W (CSC) (US SSA)]

>Marq wrote:
>> Hi
>> 
>> When i create username like this
>> "useradd user.name"
>> It shows the error message saying that the name contains invalid characters
>
>It is bad idea to create such users.  For example, chown command accepts 
>argument of type "user.group".  You should stick with letters and numbers.
>

The chown(1) man page says that a colon ":" is the delimiting character:

NAME
       chown - change file owner and group

SYNOPSIS
       chown [OPTION]... [OWNER][:[GROUP]] FILE...


My advice to Marq would be to use a dummy username, and then manually edit the passwd and shadow files.  We've been using usernames like first.m.last for several years to maintain compatibility with another operating system; the users don't like having to use the long usernames but it works.