pg_createcluster(8) create a new PostgreSQL cluster


pg_createcluster [options] version name


pg_createcluster creates a new PostgreSQL server cluster (i. e. a collection of databases served by a postmaster(1) instance) and integrates it into the multi-version/multi-cluster architecture of the postgresql-common package.

Every cluster is uniquely identified by its version and name. The name can be arbitrary. The default cluster that is created on installation of a server package is main
. However, you might wish to create other clusters for testing, with other superusers, a cluster for each user on a shared server, etc. pg_createcluster
will abort with an error if you try to create a cluster with a name that already exists for that version.

Given a major PostgreSQL version (like ``8.2'' or ``8.3'') and a cluster name, it creates the necessary configuration files in /etc/postgresql/
version /
name /
; in particular these are postgresql.conf
, pg_ident.conf
, pg_hba.conf
, a postgresql-common specific configuration file start.conf
(see STARTUP CONTROL below), pg_ctl.conf
, and a symbolic link log
which points to the log file (by default, /var/log/postgresql/postgresql-
version -
name .log

is automatically adapted to use the next available port, i. e. the first port (starting from 5432) which is not yet used by an already existing cluster.

If the data directory does not yet exist, PostgreSQL's initdb(1) command is used to generate a new cluster structure. If the data directory already exists, it is integrated into the postgresql-common structure by moving the configuration file and setting the data_directory option. Please note that this only works for data directories which were created directly with initdb, i. e. all the configuration files ( postgresql.conf
etc.) must be present in the data directory.

If a custom socket directory is given and it does not exist, it is created.

If the log file does not exist, it is created. In any case the permissions are adjusted to allow write access to the cluster owner. Please note that postgresql.conf
can be customized to specify log_directory
and/or log_filename
; if at least one of these options is present, then the symbolic link log
in the cluster configuration directory is ignored.

If the default snakeoil SSL certificate exists ( /etc/ssl/certs/ssl-cert-snakeoil.pem
and /etc/ssl/private/ssl-cert-snakeoil.key
), this program creates symlinks to these files in the data directory ( server.crt
and server.key
) and enables SSL for that cluster (option ssl in postgresql.conf
). Therefore all clusters will use the same SSL certificate by default. Of course you can replace these symlinks with a cluster specific certificate.


-u user, --user=user
Set the user who owns the cluster and becomes the database superuser to the given name or uid. By default, this is the user postgres. A cluster must not be owned by root.
-g group, --group=group
Change the group of the cluster related data files. By default this will be the primary group of the database owner.
-d dir, --datadir=dir
Explicitly set the data directory path, which is used to store all the actual databases and tables. This will become quite big (easily in the order of five times the amount of actual data stored in the cluster). Defaults to /var/lib/postgresql/
version /
-s dir, --socketdir=dir
Explicitly set the directory where the postmaster(1) server stores the Unix socket for local connections. Defaults to /var/run/postgresql/
for clusters owned by the user postgres, and /tmp
for clusters owned by other users. Please be aware that /tmp
is an unsafe directory since everybody can create a socket there and impersonate the database server. If the given directory does not exist, it is created with appropriate permissions.
-l path, --logfile=path
Explicitly set the path for the postmaster(1) server log file. Defaults to /var/log/postgresql/postgresql-
version -
cluster .log
Set the default locale for the database cluster. If this option is not specified, the locale is inherited from the environment that pg_createcluster runs in.
Like --locale, but only sets the locale in the specified category.
-e encoding, --encoding=encoding
Select the encoding of the template database. This will also be the default encoding of any database you create later, unless you override it there. The default is derived from the locale, or SQL_ASCII if that does not work. The character sets supported by the PostgreSQL server are described in the documentation.

Note: It is not recommended to set this option directly! Set the locale instead.

-p port, --port=port
Select the port the new cluster listens on (for the Unix socket and the TCP port); this must be a number between 1024 and 65535, since PostgreSQL does not run as root and thus needs an unprivileged port number. By default the next free port starting from 5432 is assigned.
Immediately start a server for the cluster after creating it (i. e. call pg_ctlcluster
version cluster start
on it). By default, the cluster is not started.
Set the initial value in the start.conf
configuration file. See STARTUP CONTROL below. By default, auto is used, which means that the cluster is handled by /etc/init.d/postgresql
, i. e. starts and stops automatically on system boot.


The start.conf
file in the cluster configuration directory controls the start/stop behavior of that cluster's postmaster process. The file can contain comment lines (started with '#'), empty lines, and must have exactly one line with one of the following keywords:
The postmaster process is started/stopped automatically in the init script. This is also the default if the file is missing.
The postmaster process is not handled by the init script, but manually controlling the cluster with pg_ctlcluster(1) is permitted.
Neither the init script nor pg_ctlcluster(1) are permitted to start/stop the cluster. Please be aware that this will not stop the cluster owner from calling lower level tools to control the postmaster process; this option is only meant to prevent accidents during maintenance, not more.

The pg_ctl.conf
file in the cluster configuration directory can contain additional options passed to pg_ctl of that cluster.


Martin Pitt <[email protected]>