cp /usr/lib/systemd/system/postgresql-12.service /usr/lib/systemd/system/pg02.service

vi /usr/lib/systemd/system/pg02.service

# Location of database directory
Environment=PGDATA=/var/lib/pgsql/12/data02/

[root@centos7-6 ~]# /usr/pgsql-12/bin/postgresql-12-setup initdb pg02

cd /var/lib/pgsql/12/data02/
vi postgresql.conf


listen_addresses = '*'    # what IP address(es) to listen on;
                          # comma-separated list of addresses;
                          # defaults to 'localhost'; use '*' for all
                          # (change requires restart)
port = 5433

vi pg_hba.conf
host     all     all             0.0.0.0/0                 md5

systemctl enable pg02
systemctl start pg02

ps -ef|grep postgres

psql -p 5432 -dpostgres
psql -p 5433 -dpostgres