On Thu, Dec 2, 2010 at 8:04 PM, Genes MailLists <lists(a)sapience.com> wrote:
On 12/02/2010 07:42 PM, Marko Vojinovic wrote:
> On Thursday 02 December 2010 21:02:17 Aaron Konstam wrote:
>> On Thu, 2010-12-02 at 18:10 +0100, Joachim Backes wrote:
>>> Can somebody explain why pure numbers are allowed for username in the
>>> useradd command?
>>>
>>> sudo useradd 123456789
>>>
>>> is not rejected!
>>>
>>> As is known, this leads to big problems if referring to such a user and
>>> the username differs from the userid: should such a username be
>>> interpreted as username or userid?
Can you be specific - what big problems are these ? Never tried, but
it is by means obvious that this would be problematic.
> So I guess 12345 should be a valid username as any other, and useradd
> correctly allows for creation of such usernames. No bug there.
Agreed - without knowing what the problems are it is hard to say that
useradd (or anything else) should disallow numerical id's ..
In Solaris, there are restrictions on the username. It has to start
with a letter, cannot start with a hyphen, and cannot contain a colon.
(There may be more restrictions; these are the ones that I remember.)
I've always assumed that Linux had the same restrictions but "man 5
passwd" on my F14 box yields nothing so I've just googled and the only
restriction that
http://www.kernel.org/doc/man-pages/online/pages/man5/passwd.5.html
sets is "It should not contain capital letters".