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3.3 Starting the Database Server

Before anyone can access the database, you must start the database server. The database server program is called postgres. The postgres program must know where to find the data it is supposed to use. This is done with the -D option. Thus, the simplest way to start the server is:

$ postgres -D /usr/local/pgsql/data

which will leave the server running in the foreground. This must be done while logged into the PostgreSQL user account. Without -D, the server will try to use the data directory named by the environment variable PGDATA. If that variable is not provided either, it will fail.

Normally it is better to start postgres in the background. For this, use the usual shell syntax:

$ postgres -D /usr/local/pgsql/data >logfile 2>&1 &

It is important to store the server's stdout and stderr output somewhere, as shown above. It will help for auditing purposes and to diagnose problems. (See section 9.3 Log File Maintenance for a more thorough discussion of log file handling.)

The postgres program also takes a number of other command-line options. For more information, see the postgres reference page and section 4 Server Configuration below.

This shell syntax can get tedious quickly. Therefore the wrapper program pg_ctl is provided to simplify some tasks. For example:

pg_ctl start -l logfile

will start the server in the background and put the output into the named log file. The -D option has the same meaning here as for postgres. pg_ctl is also capable of stopping the server.

Normally, you will want to start the database server when the computer boots. Autostart scripts are operating-system-specific. There are a few distributed with PostgreSQL in the ‘contrib/start-scripts’ directory. Installing one will require root privileges.

Different systems have different conventions for starting up daemons at boot time. Many systems have a file ‘/etc/rc.local’ or ‘/etc/rc.d/rc.local’. Others use ‘rc.d’ directories. Whatever you do, the server must be run by the PostgreSQL user account and not by root or any other user. Therefore you probably should form your commands using su -c '...' postgres. For example:

su -c 'pg_ctl start -D /usr/local/pgsql/data -l serverlog'
 postgres

Here are a few more operating-system-specific suggestions. (In each case be sure to use the proper installation directory and user name where we show generic values.)

• For FreeBSD, look at the file ‘contrib/start-scripts/freebsd’ in the PostgreSQL source distribution.
• On OpenBSD, add the following lines to the file ‘/etc/rc.local’:

  if [ -x /usr/local/pgsql/bin/pg_ctl -a -x
   /usr/local/pgsql/bin/postgres ]; then
      su - -c '/usr/local/pgsql/bin/pg_ctl start -l
   /var/postgresql/log -s' postgres
      echo -n ' postgresql'
  fi
  

• On Linux systems either add

  /usr/local/pgsql/bin/pg_ctl start -l logfile -D
   /usr/local/pgsql/data
  

  to ‘/etc/rc.d/rc.local’ or look at the file ‘contrib/start-scripts/linux’ in the PostgreSQL source distribution.
• On NetBSD, either use the FreeBSD or Linux start scripts, depending on preference.
• On Solaris, create a file called ‘/etc/init.d/postgresql’ that contains the following line:

  su - postgres -c "/usr/local/pgsql/bin/pg_ctl start -l
   logfile -D /usr/local/pgsql/data"
  

  Then, create a symbolic link to it in ‘/etc/rc3.d’ as ‘S99postgresql’.

While the server is running, its PID is stored in the file ‘postmaster.pid’ in the data directory. This is used to prevent multiple server instances from running in the same data directory and can also be used for shutting down the server.