pg_ctl — start, stop, or restart a PostgreSQL server
pg_ctl
start [-w] [-s] [-D datadir
] [-l filename
] [-o options
] [-p path
]pg_ctl
stop [-W] [-s] [-D datadir
] [-m
[s[mart]] | [f[ast]] | [i[mmediate]]
]pg_ctl
restart [-w] [-s] [-D datadir
] [-m
[s[mart]] | [f[ast]] | [i[mmediate]]
] [-o options
]pg_ctl
reload [-s] [-D datadir
]pg_ctl
status [-D datadir
]pg_ctl
kill [signal_name
] [process_id
]pg_ctl
register [-N servicename
] [-U username
] [-P password
] [-D datadir
] [-w] [-o options
]pg_ctl
unregister [-N servicename
]
pg_ctl is a utility for 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 controlled shutdown.
In start
mode, a new server is launched. The
server is started in the background, and standard input is attached to
/dev/null
. The standard output and standard
error are either appended to a log file (if the -l
option is used), or 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 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.
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 all the clients to
disconnect. This is the default. “Fast” mode does
not wait for clients to disconnect. 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
command-line options.
reload
mode simply sends the
postgres
process a SIGHUP
signal, causing it to reread its configuration files
(postgresql.conf
,
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
displayed.
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
register
command.
-D datadir
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 the
postgres
command.
The options 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 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.
-s
Only print errors, no informational messages.
-w
Wait for the start or shutdown to complete. Times out after
60 seconds. This is the default 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
or shutdown.
-W
Do not wait for start or shutdown to complete. This is the default for starts and restarts.
-N servicename
Name of the system service to register. The name will be used as both the service name and the display name.
-P password
Password for the user to start the service.
-U username
User name for the user to start the service. For domain users, use the
format DOMAIN\username
.
PGDATA
Default data directory location.
PGPORT
Default port for psql (used by the -w option).
For others, see postgres.
postmaster.pid
The existence of this file in the data directory is used to help pg_ctl determine if the server is currently running or not.
postmaster.opts.default
If this file exists in the data directory,
pg_ctl (in start
mode) will pass the contents of the file as options to the
postgres
command, unless overridden by the
-o
option.
postmaster.opts
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.
postgresql.conf
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 may fail if access control is set up so that a local client cannot connect without manual interaction (e.g., password authentication).
To start up a server:
$
pg_ctl start
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
$
pg_ctl stop
stops the server. Using the -m
switch allows one
to control how the backend shuts down.
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:
$
pg_ctl restart
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