Postgres Log Rolling

This should be an easy one, but......

We need to start rolling our postgres error logs.  I wondered whether or
not I could pull the rug out from under postgres by just renaming the
pgsql.log to 'date'.log and then recreating (touch pgsql.log) the log.

I then vacuum'd a database (so it would write stuff in the log), and
noticed that the renamed log ('date'.log) was the one written to, not the
new pgsql.log.

Do I have to bounce the cluster to roll the log?   How should I be
performing this task?

--
Naomi Walker
Chief Information Officer
Eldorado Computing, Inc.
602-604-3100  ext 242