Postgres server output log

Hi Everybody,

I am new to postgresql. I started my postgres using the command

postmaster -D /usr/local/pgsql/data > logfile 2>&1 &

Now after running it for some time I noticed that the size of this logfile has become very large. Is this logfile used to store any important information used by the database for recovery in case of crash? If no,is there any way I can specify a different log file withouting stopping the server ?

Any help is appreciated.

Thanks,

Tarun