Nothing can happen to a database unless the postmaster process is running. As the site administrator, there are a number of things you should remember before starting the postmaster. These are discussed in the installation and configuration sections of this manual. However, if Postgres has been installed by following the installation instructions exactly as written, the following simple command is all you should need to start the postmaster:
% postmaster
The postmaster occasionally prints out messages which are often helpful during troubleshooting. If you wish to view debugging messages from the postmaster, you can start it with the -d option and redirect the output to the log file:
% postmaster -d > pm.log 2>&1 &
If you do not wish to see these messages, you can type
% postmaster -S
and the postmaster will be
"S"ilent. No ampersand ("&") is required in this case, since
the postmaster automatically detaches from the terminal when -S is
specified.