pg_ctl is a utility for initializing a
PostgreSQL database cluster, starting,
stopping, or restarting the PostgreSQL
backend server (postgres), or displaying the
status of a running server. Although the server can be started
manually, pg_ctl encapsulates tasks such
as redirecting log output and properly detaching from the terminal
and process group. It also provides convenient options for
The init or initdb mode creates a
PostgreSQL database cluster. A database
cluster is a collection of databases that are managed by a single
server instance. This mode invokes the initdb
command. See initdb for details.
In start mode, a new server is launched. The
server is started in the background, and standard input is attached
to /dev/null (or nul on Windows).
On Unix-like systems, by default, the server's standard output and
standard error are send to pg_ctl's
standard output (not standard error). The standard output of
pg_ctl should then be redirected to a
file or piped to another process such as a log rotating program
like rotatelogs; otherwise postgres
will write its output to the controlling terminal (from the
background) and will not leave the shell's process group. On
Windows, by default the server's standard output and standard error
are sent to the terminal. These default behaviors can be changed
by using -l to append server output to a log file.
In stop mode, the server that is running in
the specified data directory is shut down. Three different
shutdown methods can be selected with the -m
option: "Smart" mode waits for online backup mode
to finish and all the clients to disconnect. This is the default.
If the server is in recovery, recovery and streaming replication
will be terminated once all clients have disconnected.
"Fast" mode does not wait for clients to disconnect and
will terminate an online backup in progress. All active transactions are
rolled back and clients are forcibly disconnected, then the
server is shut down. "Immediate" mode will abort
all server processes without a clean shutdown. This will lead to
a recovery run on restart.
restart mode effectively executes a stop followed
by a start. This allows changing the postgres
reload mode simply sends the
postgres process a SIGHUP
signal, causing it to reread its configuration files
pg_hba.conf, etc.). This allows changing of
configuration-file options that do not require a complete restart
to take effect.
status mode checks whether a server is running in
the specified data directory. If it is, the PID
and the command line options that were used to invoke it are
kill mode allows you to send a signal to a specified
process. This is particularly valuable for Microsoft Windows
which does not have a kill command. Use
--help to see a list of supported signal names.
register mode allows you to register a system service
on Microsoft Windows.
unregister mode allows you to unregister a system service
on Microsoft Windows, previously registered with the
Attempt to allow server crashes to produce core files, on platforms
where this available, by lifting any soft resource limit placed on
This is useful in debugging or diagnosing problems by allowing a
stack trace to be obtained from a failed server process.
Specifies the file system location of the database files. If
this is omitted, the environment variable
PGDATA is used.
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.
Specifies the shutdown mode. mode
can be smart, fast, or
immediate, or the first letter of one of
Specifies options to be passed directly to the
The options are usually surrounded by single or double
quotes to ensure that they are passed through as a group.
Specifies the location of the postgres
executable. By default the postgres executable 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 postgres executable was not found.
In init mode, this option analogously
specifies the location of the initdb
Only print errors, no informational messages.
The number of seconds to wait when waiting for start or shutdown
Wait for the start or shutdown to complete. The default wait time
is 60 seconds. This is the default option for shutdowns. A successful
shutdown is indicated by removal of the PID
file. For starting up, a successful psql -l
indicates success. pg_ctl will attempt to
use the proper port for psql. If the environment variable
PGPORT exists, that is used. Otherwise, it will see if a port
has been set in the postgresql.conf file.
If neither of those is used, it will use the default port that
PostgreSQL was compiled with
(5432 by default). When waiting, pg_ctl will
return an accurate exit code based on the success of the startup
Do not wait for start or shutdown to complete. This is the
default for starts and restarts.
Options for Windows
Name of the system service to register. The name will be used
as both the service name and the display name.
Password for the user to start the service.
User name for the user to start the service. For domain users, use the
Default data directory location.
Default host name or Unix-domain socket location for psql (used by the -w option).
Default port number for psql (used by the -w option).
For additional server variables, see postgres.
This utility, like most other PostgreSQL utilities,
also uses the environment variables supported by libpq
(see Section 31.13).
The existence of this file in the data directory is used to help
pg_ctl determine if the server is
currently running or not.
If this file exists in the data directory,
pg_ctl (in restart mode)
will pass the contents of the file as options to
postgres, unless overridden
by the -o option. The contents of this file
are also displayed in status mode.
This file, located in the data directory, is parsed to find the
proper port to use with psql when the
-w is given in start mode.
Waiting for complete start is not a well-defined operation and might
fail if access control is set up so that a local client cannot
connect without manual interaction (e.g., password authentication). For
additional connection variables, see Section 31.13,
and for passwords, also see Section 31.14.
Starting the Server
To start up a server:
An example of starting the server, blocking until the server has
come up is:
$pg_ctl -w start
For a server using port 5433, and
running without fsync, use:
$pg_ctl -o "-F -p 5433" start
Stopping the Server
stops the server. Using the -m switch allows one
to control how the backend shuts down.
Restarting the Server
Restarting the server is almost equivalent to stopping the
server and starting it again
except that pg_ctl saves and reuses the command line options that
were passed to the previously running instance. To restart
the server in the simplest form, use:
To restart server,
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
Showing the Server Status
Here is a sample status output from
$pg_ctl statuspg_ctl: server is running (pid: 13718)
Command line was:
/usr/local/pgsql/bin/postgres '-D' '/usr/local/pgsql/data' '-p' '5433' '-B' '128'
This is the command line that would be invoked in restart mode.