[CentOS] Determine next UID number

[Stephen Harris]

On Wed, Oct 13, 2010 at 05:45:15PM -0500, Les Mikesell wrote:
> On 10/13/2010 5:24 PM, Stephen Harris wrote:
> > On Wed, Oct 13, 2010 at 04:47:45PM -0400, John Kennedy wrote:
> >> the next user even though some dim bulb gave a use a UID of 4294967294 (how
> >> the hell that user can log in with a UID out of range is beyond me unless it
> >> gets truncated)...
> >
> > Who says 4294967294 is out of range?

> 64-bit, I presume?  Does your /var/log/lastlog look pretty big after 

Nope; 32bit CentOS 5.5

> that person logs in or did that get fixed?

lastlog is a sparse file.  How it looks and how big it is are two
different things.

I'm not saying there aren't problems with uids that high (pwconv, for
example, truncates to 2^32-1) but the number _is_ in range.

I've seen this before on systems where "nobody" was represented as
"-2" (eg from NIS maps on old SunOS 4 systems) rather than 65534.
When those maps were transferred to systems with 32bit uids then they
became 4294967294.  Funky stuff :-)

Heh, the kernel Documentation/highuid.txt file discussing 32bit uids is
dated January 2000.  I guess it's a little out of date, now :-)

-- 

rgds
Stephen