Using the SysV Script

The SysV-style script, if installed, operates similarly to the pg_ctl script. In fact, the SysV-style script operates as a management program that wraps around the pg_ctl command. The primary difference is that the SysV script is intended to be invoked by the root user, rather than the user who owns and runs PostgreSQL (e.g., postgres ). The script itself handles the switching of the userids at the appropriate times.

Using the SysV script instead of manually invoking pg_ctl is advantageous in that it simplifies system startup and shutdown procedures. The postgresql script file in /etc/rc.d/init.d/ is a plain text file, and can be modified in any standard text editor. Within this file you may easily locate the startup and shutdown routines, and add or remove options to pg_ctl as you most commonly use them. The pg_ctl commands are simplified by using either the single administrative start or stop parameter with the postgresql script.

The instructions for installation of the postgresql script are covered in Chapter 2. Depending on your machine's configuration, there may be more than one method of invoking the script once it has been properly installed. Remember that the actual name of the SysV script file in the /etc/rc.d/init.d/ directory may be an arbitrary name, depending on how it was copied. The most common names given to this script are postgresql and postgres .

If your system supports the service command, you should be able to use it as a wrapper to the installed PostgreSQL script with the following syntax:

service postgresql { start | stop | restart | status }

The service command accepts only the parameters described in the preceding syntax. No other options are accepted. You can modify the way any of these general modes runs by editing the script (e.g., /etc/rc.d/init.d/postgresql ) manually. Example 9-5 uses the service command to start PostgreSQL.

[root@booktown ~]# 
service postgresql start

Starting PostgreSQL: ok
[root@booktown ~]#

Alternatively, if the service command does not exist on your system, the postgresql script can be manually invoked with its complete system path:

/etc/rc.d/init.d/postgresql { start | stop | restart | status }

Example 9-6 checks the status of PostgreSQL's backend process by directly calling the postgresql script in the complete path. This assumes that your system has its SysV start-up scripts installed in the /etc/rc.d/init.d/ directory.

[root@booktown ~]# 
/etc/rc.d/init.d/postgresql status

pg_ctl: postmaster is running (pid: 13238)
Command line was:
/usr/local/pgsql/bin/postmaster '-D' '/usr/local/pgsql/data'
[root@booktown ~]#

As you can see from the output of Example 9-6, the SysV script is just a convenient wrapper to the pg_ctl command discussed in the previous section.