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ISBN : 978-2-7460-9712-4
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CentOS 2.1AS







pg_ctl − Starts, stops, or restarts postmaster


pg_ctl start [ -w ] [ -D datadir ] [ -l filename ] [ -o options ] [ -p path ]

pg_ctl stop [ -W ] [ -D datadir ] [ -m { s[mart] | f[ast] | i[mmediate] } ]

pg_ctl restart [ -w ] [ -D datadir ] [ -m { s[mart] | f[ast] | i[mmediate] } ] [ -o options ]

pg_ctl status [ -D datadir ]


pg_ctl is a utility for starting, stopping, or restarting postmaster(1), the PostgreSQL backend server, or displaying the status of a running postmaster. Although the postmaster can be started manually, pg_ctl encapulates tasks such as redirecting log output, properly detaching from the terminal and process group, and additionally provides an option for controlled shut down.

In start mode, a new postmaster is launched. The server is started in the background, the standard input attached to /dev/null. The standard output and standard error are either appended to a log file, if the -l option is used, or are redirected to pg_ctl’s standard output (not standard error). If no log file is chosen, the standard output of pg_ctl should be redirected to a file or piped to another process, for example a log rotating program, otherwise the postmaster will write its output the the controlling terminal (from the background) and will not leave the shell’s process group.

In stop mode, the postmaster that is running on the specified data directory is shut down. Three different shutdown methods can be selected with the -m option: ’’Smart’’ mode waits for all the clients to disconnect. This is the default. ’’Fast’’ mode does not wait for clients to disconnect. All active transactions will be rolled back. ’’Immediate’’ mode will abort without complete shutdown. This will lead to a recovery run on restart. By the default, stop mode waits for the shutdown to complete.

restart mode effectively executes a stop followed by a start. This allows the changing of postmaster command line options.

status mode checks whether a postmaster is running and if so displays the PID and the command line options that were used to invoke it.


Specifies the file system location of the database files. If this is omitted, the environment variable PGDATA is used.

-l filename

Append the server log output to filename. If the file does not exist, it is created. The umask is set to 077, so access to the log file from other users is disallowed by default.

-m mode

Specifies the shutdown mode. mode may be smart, fast, or immediate, or the first letter of one of these three.

-o options

Specifies options to be passed directly to postmaster.

The parameters are usually surrounded by single or double quotes to ensure that they are passed through as a group.

-p path

Specifies the location of the postmaster executable. By default the postmaster is taken from the same directory as pg_ctl, or failing that, the hard-wired installation directory. It is not necessary to use this option unless you are doing something unusual and get errors that the postmaster was not found.


Wait for the start or stutdown to complete. Times out after 60 seconds. This is the default for shutdowns.


Do not wait for start or shutdown to complete. This is the default for starts and restarts.

If the file postmaster.opts.default exists in the data directory, the contents of the file will be passed as options to the postmaster, unless overridden by the -o option.


To start up postmaster:

$ pg_ctl start

An example of starting the postmaster, blocking until postmaster comes up is:

$ pg_ctl -w start

For a postmaster using port 5433, and running without fsync, use:

$ pg_ctl -o "-F -p 5433" start

$ pg_ctl stop

stops postmaster. Using the -m switch allows one to control how the backend shuts down.

This is almost equivalent to stopping the postmaster then starting it again except that pg_ctl saves and reuses the command line options that were passed to the previously running instance. To restart postmaster in the simplest form:

$ pg_ctl restart

To restart postmaster, waiting for it to shut down and to come up:

$ pg_ctl -w restart

To restart using port 5433 and disabling fsync after restarting:

$ pg_ctl -o "-F -p 5433" restart

Here is a sample status output from pg_ctl:

$ pg_ctl status
pg_ctl: postmaster is running (pid: 13718)
Command line was:
/usr/local/pgsql/bin/postmaster ’-D’ ’/usr/local/pgsql/data’ ’-p’ ’5433’ ’-B’ ’128’

This is the command line that would be invoked in restart mode.


Waiting for complete start is not a well-defined operation and may fail if access control is set up in way that a local client cannot connect without manual interaction. It should be avoided.


postmaster(1), PostgreSQL Administrator’s Guide