postmaster

$ postmaster -D /usr/pg_data
To start the postmaster in the    background, use the usual shell syntax:
$ postmaster -D /usr/pg_data >logfile 2>&1 & 
This shell syntax can get tedious quickly.  Therefore the shell
script wrapper    pg_ctl    is provided to simplify some tasks.
For example:
$ pg_ctl start -l logfile