/Var Partition Full - How can a change PGDATA?

Hi

I´m in a big trouble. I need a help!!

My /var server partition  is full. I copied data dir to another partition. I changed owners of dirs and files (postgres.postgres) . I changed /etc/init.d/postgresql PGDATA to a new value, but when I try to load postgresql,this message appears

---pgstartup.log
runuser: warning: cannot change directory to /var/lib/pgsql: No such file or directory
runuser: warning: cannot change directory to /var/lib/pgsql: No such file or directory
----

I have a PostgreSQl 8.2.6 on a RHE4 Server
All my systems are stopped. Please a need some help.
There is no enough free space at /var . I cleaned all log files, but without success 

Thanks

Flávio Brito

PS: Excuse my english
----------------------------------------------
Some commands

# /etc/init.d/postgresql stop
# cd /var/lib/pgsql/
# cp -pr data/ /sistema/
#chown -R postgres.postgres postgresql/

#vi /etc/init.d/postgresql
---------------------------------------------------------------
PGENGINE=/usr/bin
PGPORT=5432
#PGDATA=/var/lib/pgsql/data Mudanca diretorio - particao /var cheia em 07/10/2009
PGDATA=/sistema/postgresql/data
if [ -f "$PGDATA/PG_VERSION" ] && [ -d "$PGDATA/base/template1" ]
then
        echo "Using old-style directory structure"
else
        #GDATA=/var/lib/pgsql/data
        PGDATA=/sistema/postgresql/data
fi
#PGLOG=/var/lib/pgsql/pgstartup.log
PGLOG=/sistema/postgresql/pgstartup.log

# Override defaults from /etc/sysconfig/pgsql if file is present
[ -f /etc/sysconfig/pgsql/${NAME} ] && . /etc/sysconfig/pgsql/${NAME}

export PGDATA
export PGPORT