Eliminating start error message: "unary operator expected"

Hi Forum,
What should I correct in order to eliminate the following error message on start:
Executing /etc/rc.d/init.d/postgresql start ..
Starting postgresql service: -sh: [: ==: unary operator expected
[  OK  ]

We installed a v7.3.2 and PostgreSQL seems to be running very well but we want to get rid of this message.

Thanks in advance for your response