Hi!
On Wed, Apr 26, 2006 at 08:36:51PM +0200, Nicolas François wrote:
> On Wed, Apr 26, 2006 at 04:10:36PM +0100, Reuben Thomas wrote:
> > On Debian, the constraints on the username are lowered:
> > Usernames must neither start by a dash ('-') nor contain a
> > colon (':') or an end of line ('\n'). However, it is
> > usually recommended to only use usernames that begin with a
> > lower case letter or an underscore, and are only followed by
> > lower case letters, underscores, dashes, and dollar signs. In
> > regular expression terms: [a-z_][a-z0-9_-]*[$]
oops, actually should be smth. like:
and are only followed by
lower case letters, underscores, dashes, decimal digits and
optionally terminated by dollar sign. In regular expression
terms: ^[a-z_][a-z0-9_-]*[$]?$
> Thanks for pointing this.
>
> The [a-z_][a-z0-9_-]*[$] regular expression is what is usually permitted.
Nicolas, looks that Reuben was right about this regexp
-- more correct one is ^[a-z_][a-z0-9_-]*[$]?$
i.e. ^[a-z_][a-z0-9_-]*\$?$
Let's look into original source code (libmisc/chkname.c):
/*
* User/group names must match [a-z_][a-z0-9_-]*[$]
*/
if (!*name || !((*name >= 'a' && *name <= 'z') || *name == '_'))
return 0;
while (*++name) {
if (!((*name >= 'a' && *name <= 'z') ||
(*name >= '0' && *name <= '9') ||
*name == '_' || *name == '-' ||
(*name == '$' && *(name + 1) == '\0')))
return 0;
}
Therefore, the manpage text should read not 'dollar signs'
but 'optional dollar sign' (at end of user/groupname).
Also, digits are indeed allowed but not mentioned there.
--
WBR,
xrgtn
