POSTGRES(1)             PostgreSQL 9.4.5 Documentation             POSTGRES(1)



NAME
       postgres - PostgreSQL database server

SYNOPSIS
       postgres [option...]

DESCRIPTION
       postgres is the PostgreSQL database server. In order for a client
       application to access a database it connects (over a network or
       locally) to a running postgres instance. The postgres instance then
       starts a separate server process to handle the connection.

       One postgres instance always manages the data of exactly one database
       cluster. A database cluster is a collection of databases that is stored
       at a common file system location (the "data area"). More than one
       postgres instance can run on a system at one time, so long as they use
       different data areas and different communication ports (see below).
       When postgres starts it needs to know the location of the data area.
       The location must be specified by the -D option or the PGDATA
       environment variable; there is no default. Typically, -D or PGDATA
       points directly to the data area directory created by initdb(1). Other
       possible file layouts are discussed in Section 18.2, "File Locations",
       in the documentation.

       By default postgres starts in the foreground and prints log messages to
       the standard error stream. In practical applications postgres should be
       started as a background process, perhaps at boot time.

       The postgres command can also be called in single-user mode. The
       primary use for this mode is during bootstrapping by initdb(1).
       Sometimes it is used for debugging or disaster recovery; note that
       running a single-user server is not truly suitable for debugging the
       server, since no realistic interprocess communication and locking will
       happen. When invoked in single-user mode from the shell, the user can
       enter queries and the results will be printed to the screen, but in a
       form that is more useful for developers than end users. In the
       single-user mode, the session user will be set to the user with ID 1,
       and implicit superuser powers are granted to this user. This user does
       not actually have to exist, so the single-user mode can be used to
       manually recover from certain kinds of accidental damage to the system
       catalogs.

OPTIONS
       postgres accepts the following command-line arguments. For a detailed
       discussion of the options consult Chapter 18, Server Configuration, in
       the documentation. You can save typing most of these options by setting
       up a configuration file. Some (safe) options can also be set from the
       connecting client in an application-dependent way to apply only for
       that session. For example, if the environment variable PGOPTIONS is
       set, then libpq-based clients will pass that string to the server,
       which will interpret it as postgres command-line options.

   General Purpose
       -A 0|1
           Enables run-time assertion checks, which is a debugging aid to
           detect programming mistakes. This option is only available if
           assertions were enabled when PostgreSQL was compiled. If so, the
           default is on.

       -B nbuffers
           Sets the number of shared buffers for use by the server processes.
           The default value of this parameter is chosen automatically by
           initdb. Specifying this option is equivalent to setting the
           shared_buffers configuration parameter.

       -c name=value
           Sets a named run-time parameter. The configuration parameters
           supported by PostgreSQL are described in Chapter 18, Server
           Configuration, in the documentation. Most of the other command line
           options are in fact short forms of such a parameter assignment.  -c
           can appear multiple times to set multiple parameters.

       -C name
           Prints the value of the named run-time parameter, and exits. (See
           the -c option above for details.) This can be used on a running
           server, and returns values from postgresql.conf, modified by any
           parameters supplied in this invocation. It does not reflect
           parameters supplied when the cluster was started.

           This option is meant for other programs that interact with a server
           instance, such as pg_ctl(1), to query configuration parameter
           values. User-facing applications should instead use SHOW(7) or the
           pg_settings view.

       -d debug-level
           Sets the debug level. The higher this value is set, the more
           debugging output is written to the server log. Values are from 1 to
           5. It is also possible to pass -d 0 for a specific session, which
           will prevent the server log level of the parent postgres process
           from being propagated to this session.

       -D datadir
           Specifies the file system location of the database configuration
           files. See Section 18.2, "File Locations", in the documentation for
           details.

       -e
           Sets the default date style to "European", that is DMY ordering of
           input date fields. This also causes the day to be printed before
           the month in certain date output formats. See Section 8.5,
           "Date/Time Types", in the documentation for more information.

       -F
           Disables fsync calls for improved performance, at the risk of data
           corruption in the event of a system crash. Specifying this option
           is equivalent to disabling the fsync configuration parameter. Read
           the detailed documentation before using this!

       -h hostname
           Specifies the IP host name or address on which postgres is to
           listen for TCP/IP connections from client applications. The value
           can also be a comma-separated list of addresses, or * to specify
           listening on all available interfaces. An empty value specifies not
           listening on any IP addresses, in which case only Unix-domain
           sockets can be used to connect to the server. Defaults to listening
           only on localhost. Specifying this option is equivalent to setting
           the listen_addresses configuration parameter.

       -i
           Allows remote clients to connect via TCP/IP (Internet domain)
           connections. Without this option, only local connections are
           accepted. This option is equivalent to setting listen_addresses to
           * in postgresql.conf or via -h.

           This option is deprecated since it does not allow access to the
           full functionality of listen_addresses. It's usually better to set
           listen_addresses directly.

       -k directory
           Specifies the directory of the Unix-domain socket on which postgres
           is to listen for connections from client applications. The value
           can also be a comma-separated list of directories. An empty value
           specifies not listening on any Unix-domain sockets, in which case
           only TCP/IP sockets can be used to connect to the server. The
           default value is normally /tmp, but that can be changed at build
           time. Specifying this option is equivalent to setting the
           unix_socket_directories configuration parameter.

       -l
           Enables secure connections using SSL.  PostgreSQL must have been
           compiled with support for SSL for this option to be available. For
           more information on using SSL, refer to Section 17.9, "Secure
           TCP/IP Connections with SSL", in the documentation.

       -N max-connections
           Sets the maximum number of client connections that this server will
           accept. The default value of this parameter is chosen automatically
           by initdb. Specifying this option is equivalent to setting the
           max_connections configuration parameter.

       -o extra-options
           The command-line-style options specified in extra-options are
           passed to all server processes started by this postgres process. If
           the option string contains any spaces, the entire string must be
           quoted.

           The use of this option is obsolete; all command-line options for
           server processes can be specified directly on the postgres command
           line.

       -p port
           Specifies the TCP/IP port or local Unix domain socket file
           extension on which postgres is to listen for connections from
           client applications. Defaults to the value of the PGPORT
           environment variable, or if PGPORT is not set, then defaults to the
           value established during compilation (normally 5432). If you
           specify a port other than the default port, then all client
           applications must specify the same port using either command-line
           options or PGPORT.

       -s
           Print time information and other statistics at the end of each
           command. This is useful for benchmarking or for use in tuning the
           number of buffers.

       -S work-mem
           Specifies the amount of memory to be used by internal sorts and
           hashes before resorting to temporary disk files. See the
           description of the work_mem configuration parameter in Section
           18.4.1, "Memory", in the documentation.

       -V
       --version
           Print the postgres version and exit.

       --name=value
           Sets a named run-time parameter; a shorter form of -c.

       --describe-config
           This option dumps out the server's internal configuration
           variables, descriptions, and defaults in tab-delimited COPY format.
           It is designed primarily for use by administration tools.

       -?
       --help
           Show help about postgres command line arguments, and exit.

   Semi-internal Options
       The options described here are used mainly for debugging purposes, and
       in some cases to assist with recovery of severely damaged databases.
       There should be no reason to use them in a production database setup.
       They are listed here only for use by PostgreSQL system developers.
       Furthermore, these options might change or be removed in a future
       release without notice.

       -f { s | i | o | b | t | n | m | h }
           Forbids the use of particular scan and join methods: s and i
           disable sequential and index scans respectively, o, b and t disable
           index-only scans, bitmap index scans, and TID scans respectively,
           while n, m, and h disable nested-loop, merge and hash joins
           respectively.

           Neither sequential scans nor nested-loop joins can be disabled
           completely; the -fs and -fn options simply discourage the optimizer
           from using those plan types if it has any other alternative.

       -n
           This option is for debugging problems that cause a server process
           to die abnormally. The ordinary strategy in this situation is to
           notify all other server processes that they must terminate and then
           reinitialize the shared memory and semaphores. This is because an
           errant server process could have corrupted some shared state before
           terminating. This option specifies that postgres will not
           reinitialize shared data structures. A knowledgeable system
           programmer can then use a debugger to examine shared memory and
           semaphore state.

       -O
           Allows the structure of system tables to be modified. This is used
           by initdb.

       -P
           Ignore system indexes when reading system tables, but still update
           the indexes when modifying the tables. This is useful when
           recovering from damaged system indexes.

       -t pa[rser] | pl[anner] | e[xecutor]
           Print timing statistics for each query relating to each of the
           major system modules. This option cannot be used together with the
           -s option.

       -T
           This option is for debugging problems that cause a server process
           to die abnormally. The ordinary strategy in this situation is to
           notify all other server processes that they must terminate and then
           reinitialize the shared memory and semaphores. This is because an
           errant server process could have corrupted some shared state before
           terminating. This option specifies that postgres will stop all
           other server processes by sending the signal SIGSTOP, but will not
           cause them to terminate. This permits system programmers to collect
           core dumps from all server processes by hand.

       -v protocol
           Specifies the version number of the frontend/backend protocol to be
           used for a particular session. This option is for internal use
           only.

       -W seconds
           A delay of this many seconds occurs when a new server process is
           started, after it conducts the authentication procedure. This is
           intended to give an opportunity to attach to the server process
           with a debugger.

   Options for Single-User Mode
       The following options only apply to the single-user mode.

       --single
           Selects the single-user mode. This must be the first argument on
           the command line.

       database
           Specifies the name of the database to be accessed. This must be the
           last argument on the command line. If it is omitted it defaults to
           the user name.

       -E
           Echo all commands.

       -j
           Disables use of newline as a statement delimiter.

       -r filename
           Send all server log output to filename. This option is only honored
           when supplied as a command-line option.

ENVIRONMENT
       PGCLIENTENCODING
           Default character encoding used by clients. (The clients can
           override this individually.) This value can also be set in the
           configuration file.

       PGDATA
           Default data directory location

       PGDATESTYLE
           Default value of the DateStyle run-time parameter. (The use of this
           environment variable is deprecated.)

       PGPORT
           Default port number (preferably set in the configuration file)

       TZ
           Server time zone

DIAGNOSTICS
       A failure message mentioning semget or shmget probably indicates you
       need to configure your kernel to provide adequate shared memory and
       semaphores. For more discussion see Section 17.4, "Managing Kernel
       Resources", in the documentation. You might be able to postpone
       reconfiguring your kernel by decreasing shared_buffers to reduce the
       shared memory consumption of PostgreSQL, and/or by reducing
       max_connections to reduce the semaphore consumption.

       A failure message suggesting that another server is already running
       should be checked carefully, for example by using the command

           $ ps ax | grep postgres

       or

           $ ps -ef | grep postgres

       depending on your system. If you are certain that no conflicting server
       is running, you can remove the lock file mentioned in the message and
       try again.

       A failure message indicating inability to bind to a port might indicate
       that that port is already in use by some non-PostgreSQL process. You
       might also get this error if you terminate postgres and immediately
       restart it using the same port; in this case, you must simply wait a
       few seconds until the operating system closes the port before trying
       again. Finally, you might get this error if you specify a port number
       that your operating system considers to be reserved. For example, many
       versions of Unix consider port numbers under 1024 to be "trusted" and
       only permit the Unix superuser to access them.

NOTES
       The utility command pg_ctl(1) can be used to start and shut down the
       postgres server safely and comfortably.

       If at all possible, do not use SIGKILL to kill the main postgres
       server. Doing so will prevent postgres from freeing the system
       resources (e.g., shared memory and semaphores) that it holds before
       terminating. This might cause problems for starting a fresh postgres
       run.

       To terminate the postgres server normally, the signals SIGTERM, SIGINT,
       or SIGQUIT can be used. The first will wait for all clients to
       terminate before quitting, the second will forcefully disconnect all
       clients, and the third will quit immediately without proper shutdown,
       resulting in a recovery run during restart.

       The SIGHUP signal will reload the server configuration files. It is
       also possible to send SIGHUP to an individual server process, but that
       is usually not sensible.

       To cancel a running query, send the SIGINT signal to the process
       running that command. To terminate a backend process cleanly, send
       SIGTERM to that process. See also pg_cancel_backend and
       pg_terminate_backend in Section 9.26.2, "Server Signaling Functions",
       in the documentation for the SQL-callable equivalents of these two
       actions.

       The postgres server uses SIGQUIT to tell subordinate server processes
       to terminate without normal cleanup. This signal should not be used by
       users. It is also unwise to send SIGKILL to a server process -- the
       main postgres process will interpret this as a crash and will force all
       the sibling processes to quit as part of its standard crash-recovery
       procedure.

BUGS
       The -- options will not work on FreeBSD or OpenBSD. Use -c instead.
       This is a bug in the affected operating systems; a future release of
       PostgreSQL will provide a workaround if this is not fixed.

USAGE
       To start a single-user mode server, use a command like

           postgres --single -D /usr/local/pgsql/data other-options my_database

       Provide the correct path to the database directory with -D, or make
       sure that the environment variable PGDATA is set. Also specify the name
       of the particular database you want to work in.

       Normally, the single-user mode server treats newline as the command
       entry terminator; there is no intelligence about semicolons, as there
       is in psql. To continue a command across multiple lines, you must type
       backslash just before each newline except the last one.

       But if you use the -j command line switch, then newline does not
       terminate command entry. In this case, the server will read the
       standard input until the end-of-file (EOF) marker, then process the
       input as a single command string. Backslash-newline is not treated
       specially in this case.

       To quit the session, type EOF (Control+D, usually). If you've used -j,
       two consecutive EOFs are needed to exit.

       Note that the single-user mode server does not provide sophisticated
       line-editing features (no command history, for example). Single-User
       mode also does not do any background processing, like automatic
       checkpoints.

EXAMPLES
       To start postgres in the background using default values, type:

           $ nohup postgres >logfile 2>&1 </dev/null &

       To start postgres with a specific port, e.g. 1234:

           $ postgres -p 1234

       To connect to this server using psql, specify this port with the -p
       option:

           $ psql -p 1234

       or set the environment variable PGPORT:

           $ export PGPORT=1234
           $ psql

       Named run-time parameters can be set in either of these styles:

           $ postgres -c work_mem=1234
           $ postgres --work-mem=1234

       Either form overrides whatever setting might exist for work_mem in
       postgresql.conf. Notice that underscores in parameter names can be
       written as either underscore or dash on the command line. Except for
       short-term experiments, it's probably better practice to edit the
       setting in postgresql.conf than to rely on a command-line switch to set
       a parameter.

SEE ALSO
       initdb(1), pg_ctl(1)



PostgreSQL 9.4.5                     2015                          POSTGRES(1)
