how long a backend stayed connected

Hi Guys!

I just want to know how to configure postgresql.conf
such that it will show in /var/log/posgresql when a backend
exits in PostgreSQL 7.1.3. Before, in PostgreSQL 7.0.3,
I was able to determine the length in time of a backend connection
by looking at line 'started: ...' and this line

pg-703$ cat /var/log/postgresql
<cut>
Sep 16 07:04:57 pg-703 postgres[21383]: proc_exit(0)
Sep 16 07:04:57 pg-703 postgres[21383]: shmem_exit(0)
Sep 16 07:04:57 pg-703 postgres[21383]: exit(0)
<cut>

Here is how i started/configured PostgreSQL 7.1.3.

pg-703$ cat /var/lib/pgsql/data/postmaster.opts
/usr/bin/postmaster
-p 5432
-D /var/lib/pgsql/data
-B 64
-b /usr/bin/postgres
-i
-N 32

pg-703$ cat /var/lib/pgsql/data/pg_options
verbose=2
query=1
syslog=1
hostlookup
showportnumber

Here is how my postgresql.conf (PostgreSQL 7.1.3) looks like

pg-713$ cat /var/lib/pgsql/data/postgresql.conf
tcpip_socket = true
hostname_lookup = true
show_source_port = true
max_connections = 128
sort_mem = 20480 # 20M
shared_buffers = 32768 # 256M
syslog = 2
log_connections = true
debug_print_query = true
debug_pretty_print = true

Thank you very much.

sherwin