Postgresql 8.4 似乎安装正确，根据这个：
sudo yum install postgresql
Loaded plugins: product-id, refresh-packagekit, rhnplugin, security, subscription-manager
This system is not registered to Red Hat Subscription Management. You can
use subscription-manager to register.
This system is receiving updates from RHN Classic or RHN Satellite.
Setting up Install Process
Package postgresql-8.4.13-1.el6_3.x86_64 already installed and latest version
Nothing to do
但是，当我尝试运行它时，它无法识别：
$ sudo /sbin/service postgresql initdb
postgresql: unrecognized service
这是 RHEL 6.3