[Samba] Scripting the next UID/GID number to use

[Andrew Bartlett]

On Tue, 2018-05-29 at 21:00 +0100, Rowland Penny via samba wrote:
> On Tue, 29 May 2018 15:50:44 -0400
> lingpanda101 via samba <samba at lists.samba.org> wrote:
> 
> > Hello,
> > 
> >      I'm developing a script to create a user and pass along all the 
> > necessary unix attributes required. I'm successful except when I go
> > to increment msSFU30MaxUidNumber or msSFU30MaxGidNumber. I'm not sure
> > how to use ldbedit to script this process. Any guidance would be
> > great. Thanks.
> > 
> > - James
> > 
> > 
> > 
> 
> Something like this:
> 
> # UPDATE msSFU30MaxUidNumber/msSFU30MaxGidNumber
> # Input : $1 $2
> # $1: what to update (msSFU30MaxUidNumber or msSFU30MaxGidNumber)
> # $2: Next Number
> #
> # Output : Nothing
> _updatemax () {
> echo "Updating $1"
> 
> newid="dn: CN=$domainNETBios,CN=ypservers,CN=ypServ30,CN=RpcServices,CN=System,$domainDN
> changetype: modify
> replace: $1
> $1: $2"

Actually, you would want to use (something like this, not tested):

changetype: modify
add: $1
$1: $2
delete: $1
$1: $2

This is called a constrained update, and avoids a race where the value
changes between the search and the modify.

That will then be atomic (either succeeds or fails as a whole) on one
DC, but sadly not across the whole domain, which is why it isn't part
of our standard feature-set (we don't like to create tools that have
inherent races).

That just means always run this against one specific DC to be safe. 

> echo "${newid}" | $LDBMODIFYBIN -H "$ldbdb" > /dev/null 2>&1
> if [ $? != 0 ]; then
>     echo "Error updating $1 in AD."
>     exit 1
> fi
> 
> echo "Successfully updated $1 in AD"
> }
> 
> Rowland

I hope this helps,

Andrew Bartlett

-- 
Andrew Bartlett                       http://samba.org/~abartlet/
Authentication Developer, Samba Team  http://samba.org
Samba Developer, Catalyst IT          http://catalyst.net.nz/services/samba