Lock file conflict with multiple postmasters

[Nicola Mauri <Nicola.Mauri@xxxxxxx>]

Hi,
We have two postmasters on the same
host. They are configured to listen on port 5432 of two distinct IP addresses
as follows:

/var/lib/pgsql1/data/postgresql.conf:
  listen_addresses = '10.0.0.1'
  port = 5432
/var/lib/pgsql2/data/postgresql.conf
  listen_addresses = '10.0.0.2'
  port = 5432

However, if we start the second instance
while the first one is running, we get the following error:
   FATAL:  could not
open lock file "/tmp/.s.PGSQL.5432.lock": Permission denied

So, lock filename cares only about port
number and nothing else.
In order to avoid this conflict, how
can we configure the name of lockfiles or directory where they are placed?


Thanks in advance!
Nicola