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postgres/doc/src/sgml/ref/psql-ref.sgml
Noah Misch 1f47ea7b87 Document security implications of search_path and the public schema. 
The ability to create like-named objects in different schemas opens up
the potential for users to change the behavior of other users' queries,
maliciously or accidentally.  When you connect to a PostgreSQL server,
you should remove from your search_path any schema for which a user
other than yourself or superusers holds the CREATE privilege.  If you do
not, other users holding CREATE privilege can redefine the behavior of
your commands, causing them to perform arbitrary SQL statements under
your identity.  "SET search_path = ..." and "SELECT
pg_catalog.set_config(...)" are not vulnerable to such hijacking, so one
can use either as the first command of a session.  As special
exceptions, the following client applications behave as documented
regardless of search_path settings and schema privileges: clusterdb
createdb createlang createuser dropdb droplang dropuser ecpg (not
programs it generates) initdb oid2name pg_archivecleanup pg_basebackup
pg_config pg_controldata pg_ctl pg_dump pg_dumpall pg_isready
pg_receivewal pg_recvlogical pg_resetwal pg_restore pg_rewind pg_standby
pg_test_fsync pg_test_timing pg_upgrade pg_waldump reindexdb vacuumdb
vacuumlo.  Not included are core client programs that run user-specified
SQL commands, namely psql and pgbench.  PostgreSQL encourages non-core
client applications to do likewise.

Document this in the context of libpq connections, psql connections,
dblink connections, ECPG connections, extension packaging, and schema
usage patterns.  The principal defense for applications is "SELECT
pg_catalog.set_config('search_path', '', false)", and the principal
defense for databases is "REVOKE CREATE ON SCHEMA public FROM PUBLIC".
Either one is sufficient to prevent attack.  After a REVOKE, consider
auditing the public schema for objects named like pg_catalog objects.

Authors of SECURITY DEFINER functions use some of the same defenses, and
the CREATE FUNCTION reference page already covered them thoroughly.
This is a good opportunity to audit SECURITY DEFINER functions for
robust security practice.

Back-patch to 9.3 (all supported versions).

Reviewed by Michael Paquier and Jonathan S. Katz.  Reported by Arseniy
Sharoglazov.

Security: CVE-2018-1058
2018-02-26 07:39:48 -08:00

3929 lines
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<!--
doc/src/sgml/ref/psql-ref.sgml
PostgreSQL documentation
-->
<refentry id="APP-PSQL">
<indexterm zone="app-psql">
<primary>psql</primary>
</indexterm>
<refmeta>
<refentrytitle><application>psql</application></refentrytitle>
<manvolnum>1</manvolnum>
<refmiscinfo>Application</refmiscinfo>
</refmeta>
<refnamediv>
<refname><application>psql</application></refname>
<refpurpose>
<productname>PostgreSQL</productname> interactive terminal
</refpurpose>
</refnamediv>
<refsynopsisdiv>
<cmdsynopsis>
<command>psql</command>
<arg rep="repeat"><replaceable class="parameter">option</replaceable></arg>
<arg choice="opt"><replaceable class="parameter">dbname</replaceable>
<arg choice="opt"><replaceable class="parameter">username</replaceable></arg></arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<application>psql</application> is a terminal-based front-end to
<productname>PostgreSQL</productname>. It enables you to type in
queries interactively, issue them to
<productname>PostgreSQL</productname>, and see the query results.
Alternatively, input can be from a file. In addition, it provides a
number of meta-commands and various shell-like features to
facilitate writing scripts and automating a wide variety of tasks.
</para>
</refsect1>
<refsect1 id="R1-APP-PSQL-3">
<title>Options</title>
<variablelist>
<varlistentry>
<term><option>-a</></term>
<term><option>--echo-all</></term>
<listitem>
<para>
Print all nonempty input lines to standard output as they are read.
(This does not apply to lines read interactively.) This is
equivalent to setting the variable <varname>ECHO</varname> to
<literal>all</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-A</></term>
<term><option>--no-align</></term>
<listitem>
<para>
Switches to unaligned output mode. (The default output mode is
otherwise aligned.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-b</></term>
<term><option>--echo-errors</></term>
<listitem>
<para>
Print failed SQL commands to standard error output. This is
equivalent to setting the variable <varname>ECHO</varname> to
<literal>errors</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-c <replaceable class="parameter">command</replaceable></></term>
<term><option>--command=<replaceable class="parameter">command</replaceable></></term>
<listitem>
<para>
Specifies that <application>psql</application> is to execute one
command string, <replaceable class="parameter">command</replaceable>,
and then exit. This is useful in shell scripts. Start-up files
(<filename>psqlrc</filename> and <filename>~/.psqlrc</filename>) are
ignored with this option.
</para>
<para>
<replaceable class="parameter">command</replaceable> must be either
a command string that is completely parsable by the server (i.e.,
it contains no <application>psql</application>-specific features),
or a single backslash command. Thus you cannot mix
<acronym>SQL</acronym> and <application>psql</application>
meta-commands with this option. To achieve that, you could
pipe the string into <application>psql</application>, for example:
<literal>echo '\x \\ SELECT * FROM foo;' | psql</literal>.
(<literal>\\</> is the separator meta-command.)
</para>
<para>
If the command string contains multiple SQL commands, they are
processed in a single transaction, unless there are explicit
<command>BEGIN</>/<command>COMMIT</> commands included in the
string to divide it into multiple transactions. This is
different from the behavior when the same string is fed to
<application>psql</application>'s standard input. Also, only
the result of the last SQL command is returned.
</para>
<para>
Because of these legacy behaviors, putting more than one command in
the <option>-c</option> string often has unexpected results. It's
better to feed multiple commands to <application>psql</application>'s
standard input, either using <application>echo</application> as
illustrated above, or via a shell here-document, for example:
<programlisting>
psql &lt;&lt;EOF
\x
SELECT * FROM foo;
EOF
</programlisting>
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-d <replaceable class="parameter">dbname</replaceable></></term>
<term><option>--dbname=<replaceable class="parameter">dbname</replaceable></></term>
<listitem>
<para>
Specifies the name of the database to connect to. This is
equivalent to specifying <replaceable
class="parameter">dbname</replaceable> as the first non-option
argument on the command line.
</para>
<para>
If this parameter contains an <symbol>=</symbol> sign or starts
with a valid <acronym>URI</acronym> prefix
(<literal>postgresql://</literal>
or <literal>postgres://</literal>), it is treated as a
<parameter>conninfo</parameter> string. See <xref
linkend="libpq-connstring"> for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-e</></term>
<term><option>--echo-queries</></term>
<listitem>
<para>
Copy all SQL commands sent to the server to standard output as well.
This is equivalent
to setting the variable <varname>ECHO</varname> to
<literal>queries</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-E</></term>
<term><option>--echo-hidden</></term>
<listitem>
<para>
Echo the actual queries generated by <command>\d</command> and other backslash
commands. You can use this to study <application>psql</application>'s
internal operations. This is equivalent to
setting the variable <varname>ECHO_HIDDEN</varname> to <literal>on</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-f <replaceable class="parameter">filename</replaceable></></term>
<term><option>--file=<replaceable class="parameter">filename</replaceable></></term>
<listitem>
<para>
Use the file <replaceable class="parameter">filename</replaceable>
as the source of commands instead of reading commands interactively.
After the file is processed, <application>psql</application>
terminates. This is in many ways equivalent to the meta-command
<command>\i</command>.
</para>
<para>
If <replaceable>filename</replaceable> is <literal>-</literal>
(hyphen), then standard input is read until an EOF indication
or <command>\q</> meta-command. Note however that Readline
is not used in this case (much as if <option>-n</option> had been
specified).
</para>
<para>
Using this option is subtly different from writing <literal>psql
&lt; <replaceable
class="parameter">filename</replaceable></literal>. In general,
both will do what you expect, but using <literal>-f</literal>
enables some nice features such as error messages with line
numbers. There is also a slight chance that using this option will
reduce the start-up overhead. On the other hand, the variant using
the shell's input redirection is (in theory) guaranteed to yield
exactly the same output you would have received had you entered
everything by hand.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-F <replaceable class="parameter">separator</replaceable></></term>
<term><option>--field-separator=<replaceable class="parameter">separator</replaceable></></term>
<listitem>
<para>
Use <replaceable class="parameter">separator</replaceable> as the
field separator for unaligned output. This is equivalent to
<command>\pset fieldsep</command> or <command>\f</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-h <replaceable class="parameter">hostname</replaceable></></term>
<term><option>--host=<replaceable class="parameter">hostname</replaceable></></term>
<listitem>
<para>
Specifies the host name of the machine on which the
server is running. If the value begins
with a slash, it is used as the directory for the Unix-domain
socket.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-H</></term>
<term><option>--html</></term>
<listitem>
<para>
Turn on <acronym>HTML</acronym> tabular output. This is
equivalent to <literal>\pset format html</literal> or the
<command>\H</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-l</></term>
<term><option>--list</></term>
<listitem>
<para>
List all available databases, then exit. Other non-connection
options are ignored. This is similar to the meta-command
<command>\list</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-L <replaceable class="parameter">filename</replaceable></></term>
<term><option>--log-file=<replaceable class="parameter">filename</replaceable></></term>
<listitem>
<para>
Write all query output into file <replaceable
class="parameter">filename</replaceable>, in addition to the
normal output destination.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-n</></term>
<term><option>--no-readline</></term>
<listitem>
<para>
Do not use <application>Readline</application> for line editing and do
not use the command history.
This can be useful to turn off tab expansion when cutting and pasting.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-o <replaceable class="parameter">filename</replaceable></></term>
<term><option>--output=<replaceable class="parameter">filename</replaceable></></term>
<listitem>
<para>
Put all query output into file <replaceable
class="parameter">filename</replaceable>. This is equivalent to
the command <command>\o</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-p <replaceable class="parameter">port</replaceable></></term>
<term><option>--port=<replaceable class="parameter">port</replaceable></></term>
<listitem>
<para>
Specifies the TCP port or the local Unix-domain
socket file extension on which the server is listening for
connections. Defaults to the value of the <envar>PGPORT</envar>
environment variable or, if not set, to the port specified at
compile time, usually 5432.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-P <replaceable class="parameter">assignment</replaceable></></term>
<term><option>--pset=<replaceable class="parameter">assignment</replaceable></></term>
<listitem>
<para>
Specifies printing options, in the style of
<command>\pset</command>. Note that here you
have to separate name and value with an equal sign instead of a
space. For example, to set the output format to <application>LaTeX</application>, you could write
<literal>-P format=latex</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-q</></term>
<term><option>--quiet</></term>
<listitem>
<para>
Specifies that <application>psql</application> should do its work
quietly. By default, it prints welcome messages and various
informational output. If this option is used, none of this
happens. This is useful with the <option>-c</option> option.
This is equivalent to setting the variable <varname>QUIET</varname>
to <literal>on</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-R <replaceable class="parameter">separator</replaceable></></term>
<term><option>--record-separator=<replaceable class="parameter">separator</replaceable></></term>
<listitem>
<para>
Use <replaceable class="parameter">separator</replaceable> as the
record separator for unaligned output. This is equivalent to the
<command>\pset recordsep</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-s</></term>
<term><option>--single-step</></term>
<listitem>
<para>
Run in single-step mode. That means the user is prompted before
each command is sent to the server, with the option to cancel
execution as well. Use this to debug scripts.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-S</></term>
<term><option>--single-line</></term>
<listitem>
<para>
Runs in single-line mode where a newline terminates an SQL command, as a
semicolon does.
</para>
<note>
<para>
This mode is provided for those who insist on it, but you are not
necessarily encouraged to use it. In particular, if you mix
<acronym>SQL</acronym> and meta-commands on a line the order of
execution might not always be clear to the inexperienced user.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t</></term>
<term><option>--tuples-only</></term>
<listitem>
<para>
Turn off printing of column names and result row count footers,
etc. This is equivalent to the <command>\t</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-T <replaceable class="parameter">table_options</replaceable></></term>
<term><option>--table-attr=<replaceable class="parameter">table_options</replaceable></></term>
<listitem>
<para>
Specifies options to be placed within the
<acronym>HTML</acronym> <sgmltag>table</sgmltag> tag. See
<command>\pset</command> for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-U <replaceable class="parameter">username</replaceable></></term>
<term><option>--username=<replaceable class="parameter">username</replaceable></></term>
<listitem>
<para>
Connect to the database as the user <replaceable
class="parameter">username</replaceable> instead of the default.
(You must have permission to do so, of course.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v <replaceable class="parameter">assignment</replaceable></></term>
<term><option>--set=<replaceable class="parameter">assignment</replaceable></></term>
<term><option>--variable=<replaceable class="parameter">assignment</replaceable></></term>
<listitem>
<para>
Perform a variable assignment, like the <command>\set</command>
meta-command. Note that you must separate name and value, if
any, by an equal sign on the command line. To unset a variable,
leave off the equal sign. To set a variable with an empty value,
use the equal sign but leave off the value. These assignments are
done during a very early stage of start-up, so variables reserved
for internal purposes might get overwritten later.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-V</></term>
<term><option>--version</></term>
<listitem>
<para>
Print the <application>psql</application> version and exit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-w</></term>
<term><option>--no-password</></term>
<listitem>
<para>
Never issue a password prompt. If the server requires password
authentication and a password is not available by other means
such as a <filename>.pgpass</filename> file, the connection
attempt will fail. This option can be useful in batch jobs and
scripts where no user is present to enter a password.
</para>
<para>
Note that this option will remain set for the entire session,
and so it affects uses of the meta-command
<command>\connect</command> as well as the initial connection attempt.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-W</></term>
<term><option>--password</></term>
<listitem>
<para>
Force <application>psql</application> to prompt for a
password before connecting to a database.
</para>
<para>
This option is never essential, since <application>psql</application>
will automatically prompt for a password if the server demands
password authentication. However, <application>psql</application>
will waste a connection attempt finding out that the server wants a
password. In some cases it is worth typing <option>-W</> to avoid
the extra connection attempt.
</para>
<para>
Note that this option will remain set for the entire session,
and so it affects uses of the meta-command
<command>\connect</command> as well as the initial connection attempt.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-x</></term>
<term><option>--expanded</></term>
<listitem>
<para>
Turn on the expanded table formatting mode. This is equivalent to the
<command>\x</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-X,</></term>
<term><option>--no-psqlrc</></term>
<listitem>
<para>
Do not read the start-up file (neither the system-wide
<filename>psqlrc</filename> file nor the user's
<filename>~/.psqlrc</filename> file).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-z</option></term>
<term><option>--field-separator-zero</option></term>
<listitem>
<para>
Set the field separator for unaligned output to a zero byte.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-0</option></term>
<term><option>--record-separator-zero</option></term>
<listitem>
<para>
Set the record separator for unaligned output to a zero byte. This is
useful for interfacing, for example, with <literal>xargs -0</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-1</option></term>
<term><option>--single-transaction</option></term>
<listitem>
<para>
When <application>psql</application> executes a script, adding
this option wraps <command>BEGIN</>/<command>COMMIT</> around the
script to execute it as a single transaction. This ensures that
either all the commands complete successfully, or no changes are
applied.
</para>
<para>
If the script itself uses <command>BEGIN</>, <command>COMMIT</>,
or <command>ROLLBACK</>, this option will not have the desired
effects.
Also, if the script contains any command that cannot be executed
inside a transaction block, specifying this option will cause that
command (and hence the whole transaction) to fail.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-?</></term>
<term><option>--help[=<replaceable class="parameter">topic</>]</option></term>
<listitem>
<para>
Show help about <application>psql</application> and exit. The optional
<replaceable class="parameter">topic</> parameter (defaulting
to <literal>options</literal>) selects which part of <application>psql</application> is
explained: <literal>commands</> describes <application>psql</>'s
backslash commands; <literal>options</> describes the command-line
options that can be passed to <application>psql</>;
and <literal>variables</> shows help about <application>psql</application> configuration
variables.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit Status</title>
<para>
<application>psql</application> returns 0 to the shell if it
finished normally, 1 if a fatal error of its own occurs (e.g. out of memory,
file not found), 2 if the connection to the server went bad
and the session was not interactive, and 3 if an error occurred in a
script and the variable <varname>ON_ERROR_STOP</varname> was set.
</para>
</refsect1>
<refsect1>
<title>Usage</title>
<refsect2 id="R2-APP-PSQL-connecting">
<title>Connecting to a Database</title>
<para>
<application>psql</application> is a regular
<productname>PostgreSQL</productname> client application. In order
to connect to a database you need to know the name of your target
database, the host name and port number of the server, and what user
name you want to connect as. <application>psql</application> can be
told about those parameters via command line options, namely
<option>-d</option>, <option>-h</option>, <option>-p</option>, and
<option>-U</option> respectively. If an argument is found that does
not belong to any option it will be interpreted as the database name
(or the user name, if the database name is already given). Not all
of these options are required; there are useful defaults. If you omit the host
name, <application>psql</> will connect via a Unix-domain socket
to a server on the local host, or via TCP/IP to <literal>localhost</> on
machines that don't have Unix-domain sockets. The default port number is
determined at compile time.
Since the database server uses the same default, you will not have
to specify the port in most cases. The default user name is your
operating-system user name, as is the default database name.
Note that you cannot
just connect to any database under any user name. Your database
administrator should have informed you about your access rights.
</para>
<para>
When the defaults aren't quite right, you can save yourself
some typing by setting the environment variables
<envar>PGDATABASE</envar>, <envar>PGHOST</envar>,
<envar>PGPORT</envar> and/or <envar>PGUSER</envar> to appropriate
values. (For additional environment variables, see <xref
linkend="libpq-envars">.) It is also convenient to have a
<filename>~/.pgpass</> file to avoid regularly having to type in
passwords. See <xref linkend="libpq-pgpass"> for more information.
</para>
<para>
An alternative way to specify connection parameters is in a
<parameter>conninfo</parameter> string or
a <acronym>URI</acronym>, which is used instead of a database
name. This mechanism give you very wide control over the
connection. For example:
<programlisting>
$ <userinput>psql "service=myservice sslmode=require"</userinput>
$ <userinput>psql postgresql://dbmaster:5433/mydb?sslmode=require</userinput>
</programlisting>
This way you can also use <acronym>LDAP</acronym> for connection
parameter lookup as described in <xref linkend="libpq-ldap">.
See <xref linkend="libpq-paramkeywords"> for more information on all the
available connection options.
</para>
<para>
If the connection could not be made for any reason (e.g., insufficient
privileges, server is not running on the targeted host, etc.),
<application>psql</application> will return an error and terminate.
</para>
<para>
If both standard input and standard output are a
terminal, then <application>psql</application> sets the client
encoding to <quote>auto</quote>, which will detect the
appropriate client encoding from the locale settings
(<envar>LC_CTYPE</envar> environment variable on Unix systems).
If this doesn't work out as expected, the client encoding can be
overridden using the environment
variable <envar>PGCLIENTENCODING</envar>.
</para>
</refsect2>
<refsect2 id="R2-APP-PSQL-4">
<title>Entering SQL Commands</title>
<para>
In normal operation, <application>psql</application> provides a
prompt with the name of the database to which
<application>psql</application> is currently connected, followed by
the string <literal>=&gt;</literal>. For example:
<programlisting>
$ <userinput>psql testdb</userinput>
psql (&version;)
Type "help" for help.
testdb=&gt;
</programlisting>
</para>
<para>
At the prompt, the user can type in <acronym>SQL</acronym> commands.
Ordinarily, input lines are sent to the server when a
command-terminating semicolon is reached. An end of line does not
terminate a command. Thus commands can be spread over several lines for
clarity. If the command was sent and executed without error, the results
of the command are displayed on the screen.
</para>
<para>
If untrusted users have access to a database that has not adopted a
<link linkend="ddl-schemas-patterns">secure schema usage pattern</link>,
begin your session by removing publicly-writable schemas
from <varname>search_path</varname>. One can
add <literal>options=-csearch_path=</literal> to the connection string or
issue <literal>SELECT pg_catalog.set_config('search_path', '',
false)</literal> before other SQL commands. This consideration is not
specific to <application>psql</application>; it applies to every interface
for executing arbitrary SQL commands.
</para>
<para>
Whenever a command is executed, <application>psql</application> also polls
for asynchronous notification events generated by
<xref linkend="SQL-LISTEN"> and
<xref linkend="SQL-NOTIFY">.
</para>
<para>
While C-style block comments are passed to the server for
processing and removal, SQL-standard comments are removed by
<application>psql</application>.
</para>
</refsect2>
<refsect2 id="APP-PSQL-meta-commands">
<title>Meta-Commands</title>
<para>
Anything you enter in <application>psql</application> that begins
with an unquoted backslash is a <application>psql</application>
meta-command that is processed by <application>psql</application>
itself. These commands make
<application>psql</application> more useful for administration or
scripting. Meta-commands are often called slash or backslash commands.
</para>
<para>
The format of a <application>psql</application> command is the backslash,
followed immediately by a command verb, then any arguments. The arguments
are separated from the command verb and each other by any number of
whitespace characters.
</para>
<para>
To include whitespace in an argument you can quote it with
single quotes. To include a single quote in an argument,
write two single quotes within single-quoted text.
Anything contained in single quotes is
furthermore subject to C-like substitutions for
<literal>\n</literal> (new line), <literal>\t</literal> (tab),
<literal>\b</literal> (backspace), <literal>\r</literal> (carriage return),
<literal>\f</literal> (form feed),
<literal>\</literal><replaceable>digits</replaceable> (octal), and
<literal>\x</literal><replaceable>digits</replaceable> (hexadecimal).
A backslash preceding any other character within single-quoted text
quotes that single character, whatever it is.
</para>
<para>
Within an argument, text that is enclosed in backquotes
(<literal>`</literal>) is taken as a command line that is passed to the
shell. The output of the command (with any trailing newline removed)
replaces the backquoted text.
</para>
<para>
If an unquoted colon (<literal>:</literal>) followed by a
<application>psql</> variable name appears within an argument, it is
replaced by the variable's value, as described in <xref
linkend="APP-PSQL-interpolation" endterm="APP-PSQL-interpolation-title">.
</para>
<para>
Some commands take an <acronym>SQL</acronym> identifier (such as a
table name) as argument. These arguments follow the syntax rules
of <acronym>SQL</acronym>: Unquoted letters are forced to
lowercase, while double quotes (<literal>"</>) protect letters
from case conversion and allow incorporation of whitespace into
the identifier. Within double quotes, paired double quotes reduce
to a single double quote in the resulting name. For example,
<literal>FOO"BAR"BAZ</> is interpreted as <literal>fooBARbaz</>,
and <literal>"A weird"" name"</> becomes <literal>A weird"
name</>.
</para>
<para>
Parsing for arguments stops at the end of the line, or when another
unquoted backslash is found. An unquoted backslash
is taken as the beginning of a new meta-command. The special
sequence <literal>\\</literal> (two backslashes) marks the end of
arguments and continues parsing <acronym>SQL</acronym> commands, if
any. That way <acronym>SQL</acronym> and
<application>psql</application> commands can be freely mixed on a
line. But in any case, the arguments of a meta-command cannot
continue beyond the end of the line.
</para>
<para>
The following meta-commands are defined:
<variablelist>
<varlistentry>
<term><literal>\a</literal></term>
<listitem>
<para>
If the current table output format is unaligned, it is switched to aligned.
If it is not unaligned, it is set to unaligned. This command is
kept for backwards compatibility. See <command>\pset</command> for a
more general solution.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\c</literal> or <literal>\connect [ -reuse-previous=<replaceable class="parameter">on|off</replaceable> ] [ <replaceable class="parameter">dbname</replaceable> [ <replaceable class="parameter">username</replaceable> ] [ <replaceable class="parameter">host</replaceable> ] [ <replaceable class="parameter">port</replaceable> ] | <replaceable class="parameter">conninfo</replaceable> ]</literal></term>
<listitem>
<para>
Establishes a new connection to a <productname>PostgreSQL</>
server. The connection parameters to use can be specified either
using a positional syntax, or using <literal>conninfo</> connection
strings as detailed in <xref linkend="libpq-connstring">.
</para>
<para>
Where the command omits database name, user, host, or port, the new
connection can reuse values from the previous connection. By default,
values from the previous connection are reused except when processing
a <literal>conninfo</> string. Passing a first argument
of <literal>-reuse-previous=on</>
or <literal>-reuse-previous=off</literal> overrides that default.
When the command neither specifies nor reuses a particular parameter,
the <application>libpq</application> default is used. Specifying any
of <replaceable class="parameter">dbname</replaceable>,
<replaceable class="parameter">username</replaceable>,
<replaceable class="parameter">host</replaceable> or
<replaceable class="parameter">port</replaceable>
as <literal>-</literal> is equivalent to omitting that parameter.
</para>
<para>
If the new connection is successfully made, the previous
connection is closed.
If the connection attempt failed (wrong user name, access
denied, etc.), the previous connection will only be kept if
<application>psql</application> is in interactive mode. When
executing a non-interactive script, processing will
immediately stop with an error. This distinction was chosen as
a user convenience against typos on the one hand, and a safety
mechanism that scripts are not accidentally acting on the
wrong database on the other hand.
</para>
<para>
Examples:
</para>
<programlisting>
=&gt; \c mydb myuser host.dom 6432
=&gt; \c service=foo
=&gt; \c "host=localhost port=5432 dbname=mydb connect_timeout=10 sslmode=disable"
=&gt; \c postgresql://tom@localhost/mydb?application_name=myapp
</programlisting>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\C [ <replaceable class="parameter">title</replaceable> ]</literal></term>
<listitem>
<para>
Sets the title of any tables being printed as the result of a
query or unset any such title. This command is equivalent to
<literal>\pset title <replaceable
class="parameter">title</replaceable></literal>. (The name of
this command derives from <quote>caption</quote>, as it was
previously only used to set the caption in an
<acronym>HTML</acronym> table.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\cd [ <replaceable>directory</replaceable> ]</literal></term>
<listitem>
<para>
Changes the current working directory to
<replaceable>directory</replaceable>. Without argument, changes
to the current user's home directory.
</para>
<tip>
<para>
To print your current working directory, use <literal>\! pwd</literal>.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\conninfo</literal></term>
<listitem>
<para>
Outputs information about the current database connection.
</para>
</listitem>
</varlistentry>
<varlistentry id="APP-PSQL-meta-commands-copy">
<term><literal>\copy { <replaceable class="parameter">table</replaceable> [ ( <replaceable class="parameter">column_list</replaceable> ) ] | ( <replaceable class="parameter">query</replaceable> ) }
{ <literal>from</literal> | <literal>to</literal> }
{ <replaceable class="parameter">'filename'</replaceable> | program <replaceable class="parameter">'command'</replaceable> | stdin | stdout | pstdin | pstdout }
[ [ with ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ]</literal></term>
<listitem>
<para>
Performs a frontend (client) copy. This is an operation that
runs an <acronym>SQL</acronym> <xref linkend="SQL-COPY">
command, but instead of the server
reading or writing the specified file,
<application>psql</application> reads or writes the file and
routes the data between the server and the local file system.
This means that file accessibility and privileges are those of
the local user, not the server, and no SQL superuser
privileges are required.
</para>
<para>
When <literal>program</> is specified,
<replaceable class="parameter">command</replaceable> is
executed by <application>psql</application> and the data passed from
or to <replaceable class="parameter">command</replaceable> is
routed between the server and the client.
Again, the execution privileges are those of
the local user, not the server, and no SQL superuser
privileges are required.
</para>
<para>
For <literal>\copy ... from stdin</>, data rows are read from the same
source that issued the command, continuing until <literal>\.</literal>
is read or the stream reaches <acronym>EOF</>. This option is useful
for populating tables in-line within a SQL script file.
For <literal>\copy ... to stdout</>, output is sent to the same place
as <application>psql</> command output, and
the <literal>COPY <replaceable>count</></literal> command status is
not printed (since it might be confused with a data row).
To read/write <application>psql</application>'s standard input or
output regardless of the current command source or <literal>\o</>
option, write <literal>from pstdin</> or <literal>to pstdout</>.
</para>
<para>
The syntax of this command is similar to that of the
<acronym>SQL</acronym> <xref linkend="sql-copy">
command. All options other than the data source/destination are
as specified for <xref linkend="sql-copy">.
Because of this, special parsing rules apply to the <command>\copy</>
command. In particular, <application>psql</>'s variable substitution
rules and backslash escapes do not apply.
</para>
<tip>
<para>
This operation is not as efficient as the <acronym>SQL</acronym>
<command>COPY</command> command because all data must pass
through the client/server connection. For large
amounts of data the <acronym>SQL</acronym> command might be preferable.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\copyright</literal></term>
<listitem>
<para>
Shows the copyright and distribution terms of
<productname>PostgreSQL</productname>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\d[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
For each relation (table, view, materialized view, index, sequence,
or foreign table)
or composite type matching the
<replaceable class="parameter">pattern</replaceable>, show all
columns, their types, the tablespace (if not the default) and any
special attributes such as <literal>NOT NULL</literal> or defaults.
Associated indexes, constraints, rules, and triggers are
also shown. For foreign tables, the associated foreign
server is shown as well.
(<quote>Matching the pattern</> is defined in
<xref linkend="APP-PSQL-patterns" endterm="APP-PSQL-patterns-title">
below.)
</para>
<para>
For some types of relation, <literal>\d</> shows additional information
for each column: column values for sequences, indexed expressions for
indexes, and foreign data wrapper options for foreign tables.
</para>
<para>
The command form <literal>\d+</literal> is identical, except that
more information is displayed: any comments associated with the
columns of the table are shown, as is the presence of OIDs in the
table, the view definition if the relation is a view, a non-default
<link linkend="SQL-CREATETABLE-REPLICA-IDENTITY">replica
identity</link> setting.
</para>
<para>
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
<note>
<para>
If <command>\d</command> is used without a
<replaceable class="parameter">pattern</replaceable> argument, it is
equivalent to <command>\dtvmsE</command> which will show a list of
all visible tables, views, materialized views, sequences and
foreign tables.
This is purely a convenience measure.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\da[S] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists aggregate functions, together with their
return type and the data types they operate on. If <replaceable
class="parameter">pattern</replaceable>
is specified, only aggregates whose names match the pattern are shown.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\db[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists tablespaces. If <replaceable
class="parameter">pattern</replaceable>
is specified, only tablespaces whose names match the pattern are shown.
If <literal>+</literal> is appended to the command name, each tablespace
is listed with its associated options, on-disk size, permissions and
description.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dc[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists conversions between character-set encodings.
If <replaceable class="parameter">pattern</replaceable>
is specified, only conversions whose names match the pattern are
listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
If <literal>+</literal> is appended to the command name, each object
is listed with its associated description.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dC[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists type casts.
If <replaceable class="parameter">pattern</replaceable>
is specified, only casts whose source or target types match the
pattern are listed.
If <literal>+</literal> is appended to the command name, each object
is listed with its associated description.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dd[S] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Shows the descriptions of objects of type <literal>constraint</>,
<literal>operator class</>, <literal>operator family</>,
<literal>rule</>, and <literal>trigger</>. All
other comments may be viewed by the respective backslash commands for
those object types.
</para>
<para><literal>\dd</literal> displays descriptions for objects matching the
<replaceable class="parameter">pattern</replaceable>, or of visible
objects of the appropriate type if no argument is given. But in either
case, only objects that have a description are listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
<para>
Descriptions for objects can be created with the <xref
linkend="sql-comment">
<acronym>SQL</acronym> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ddp [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists default access privilege settings. An entry is shown for
each role (and schema, if applicable) for which the default
privilege settings have been changed from the built-in defaults.
If <replaceable class="parameter">pattern</replaceable> is
specified, only entries whose role name or schema name matches
the pattern are listed.
</para>
<para>
The <xref linkend="sql-alterdefaultprivileges"> command is used to set
default access privileges. The meaning of the
privilege display is explained under
<xref linkend="sql-grant">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dD[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists domains. If <replaceable
class="parameter">pattern</replaceable>
is specified, only domains whose names match the pattern are shown.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
If <literal>+</literal> is appended to the command name, each object
is listed with its associated permissions and description.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dE[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<term><literal>\di[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<term><literal>\dm[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<term><literal>\ds[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<term><literal>\dt[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<term><literal>\dv[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
In this group of commands, the letters <literal>E</literal>,
<literal>i</literal>, <literal>m</literal>, <literal>s</literal>,
<literal>t</literal>, and <literal>v</literal>
stand for foreign table, index, materialized view, sequence, table, and view,
respectively.
You can specify any or all of
these letters, in any order, to obtain a listing of objects
of these types. For example, <literal>\dit</> lists indexes
and tables. If <literal>+</literal> is
appended to the command name, each object is listed with its
physical size on disk and its associated description, if any.
If <replaceable class="parameter">pattern</replaceable> is
specified, only objects whose names match the pattern are listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\des[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists foreign servers (mnemonic: <quote>external
servers</quote>).
If <replaceable class="parameter">pattern</replaceable> is
specified, only those servers whose name matches the pattern
are listed. If the form <literal>\des+</literal> is used, a
full description of each server is shown, including the
server's ACL, type, version, options, and description.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\det[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists foreign tables (mnemonic: <quote>external tables</quote>).
If <replaceable class="parameter">pattern</replaceable> is
specified, only entries whose table name or schema name matches
the pattern are listed. If the form <literal>\det+</literal>
is used, generic options and the foreign table description
are also displayed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\deu[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists user mappings (mnemonic: <quote>external
users</quote>).
If <replaceable class="parameter">pattern</replaceable> is
specified, only those mappings whose user names match the
pattern are listed. If the form <literal>\deu+</literal> is
used, additional information about each mapping is shown.
</para>
<caution>
<para>
<literal>\deu+</literal> might also display the user name and
password of the remote user, so care should be taken not to
disclose them.
</para>
</caution>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dew[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists foreign-data wrappers (mnemonic: <quote>external
wrappers</quote>).
If <replaceable class="parameter">pattern</replaceable> is
specified, only those foreign-data wrappers whose name matches
the pattern are listed. If the form <literal>\dew+</literal>
is used, the ACL, options, and description of the foreign-data
wrapper are also shown.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\df[antwS+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists functions, together with their arguments, return types, and
function types, which are classified as <quote>agg</> (aggregate),
<quote>normal</>, <quote>trigger</>, or <quote>window</>.
To display only functions
of specific type(s), add the corresponding letters <literal>a</>,
<literal>n</>, <literal>t</>, or <literal>w</> to the command.
If <replaceable
class="parameter">pattern</replaceable> is specified, only
functions whose names match the pattern are shown.
By default, only user-created
objects are shown; supply a pattern or the <literal>S</literal>
modifier to include system objects.
If the form <literal>\df+</literal> is used, additional information
about each function is shown, including security classification,
volatility, owner, language, source code and description.
</para>
<tip>
<para>
To look up functions taking arguments or returning values of a specific
type, use your pager's search capability to scroll through the
<literal>\df</> output.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dF[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search configurations.
If <replaceable class="parameter">pattern</replaceable> is specified,
only configurations whose names match the pattern are shown.
If the form <literal>\dF+</literal> is used, a full description of
each configuration is shown, including the underlying text search
parser and the dictionary list for each parser token type.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dFd[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search dictionaries.
If <replaceable class="parameter">pattern</replaceable> is specified,
only dictionaries whose names match the pattern are shown.
If the form <literal>\dFd+</literal> is used, additional information
is shown about each selected dictionary, including the underlying
text search template and the option values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dFp[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search parsers.
If <replaceable class="parameter">pattern</replaceable> is specified,
only parsers whose names match the pattern are shown.
If the form <literal>\dFp+</literal> is used, a full description of
each parser is shown, including the underlying functions and the
list of recognized token types.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dFt[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search templates.
If <replaceable class="parameter">pattern</replaceable> is specified,
only templates whose names match the pattern are shown.
If the form <literal>\dFt+</literal> is used, additional information
is shown about each template, including the underlying function names.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dg[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists database roles.
(Since the concepts of <quote>users</> and <quote>groups</> have been
unified into <quote>roles</>, this command is now equivalent to
<literal>\du</literal>.)
If <replaceable class="parameter">pattern</replaceable> is specified,
only those roles whose names match the pattern are listed.
If the form <literal>\dg+</literal> is used, additional information
is shown about each role; currently this adds the comment for each
role.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dl</literal></term>
<listitem>
<para>
This is an alias for <command>\lo_list</command>, which shows a
list of large objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dL[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists procedural languages. If <replaceable
class="parameter">pattern</replaceable>
is specified, only languages whose names match the pattern are listed.
By default, only user-created languages
are shown; supply the <literal>S</literal> modifier to include system
objects. If <literal>+</literal> is appended to the command name, each
language is listed with its call handler, validator, access privileges,
and whether it is a system object.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dn[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists schemas (namespaces). If <replaceable
class="parameter">pattern</replaceable>
is specified, only schemas whose names match the pattern are listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system objects.
If <literal>+</literal> is appended to the command name, each object
is listed with its associated permissions and description, if any.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\do[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists operators with their operand and result types.
If <replaceable class="parameter">pattern</replaceable> is
specified, only operators whose names match the pattern are listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
If <literal>+</literal> is appended to the command name,
additional information about each operator is shown, currently just
the name of the underlying function.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dO[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists collations.
If <replaceable class="parameter">pattern</replaceable> is
specified, only collations whose names match the pattern are
listed. By default, only user-created objects are shown;
supply a pattern or the <literal>S</literal> modifier to
include system objects. If <literal>+</literal> is appended
to the command name, each collation is listed with its associated
description, if any.
Note that only collations usable with the current database's encoding
are shown, so the results may vary in different databases of the
same installation.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dp [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists tables, views and sequences with their
associated access privileges.
If <replaceable class="parameter">pattern</replaceable> is
specified, only tables, views and sequences whose names match the
pattern are listed.
</para>
<para>
The <xref linkend="sql-grant"> and
<xref linkend="sql-revoke">
commands are used to set access privileges. The meaning of the
privilege display is explained under
<xref linkend="sql-grant">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\drds [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">role-pattern</replaceable></link> [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">database-pattern</replaceable></link> ] ]</literal></term>
<listitem>
<para>
Lists defined configuration settings. These settings can be
role-specific, database-specific, or both.
<replaceable>role-pattern</replaceable> and
<replaceable>database-pattern</replaceable> are used to select
specific roles and databases to list, respectively. If omitted, or if
<literal>*</> is specified, all settings are listed, including those
not role-specific or database-specific, respectively.
</para>
<para>
The <xref linkend="sql-alterrole"> and
<xref linkend="sql-alterdatabase">
commands are used to define per-role and per-database configuration
settings.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dT[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists data types.
If <replaceable class="parameter">pattern</replaceable> is
specified, only types whose names match the pattern are listed.
If <literal>+</literal> is appended to the command name, each type is
listed with its internal name and size, its allowed values
if it is an <type>enum</> type, and its associated permissions.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\du[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists database roles.
(Since the concepts of <quote>users</> and <quote>groups</> have been
unified into <quote>roles</>, this command is now equivalent to
<literal>\dg</literal>.)
If <replaceable class="parameter">pattern</replaceable> is specified,
only those roles whose names match the pattern are listed.
If the form <literal>\du+</literal> is used, additional information
is shown about each role; currently this adds the comment for each
role.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dx[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists installed extensions.
If <replaceable class="parameter">pattern</replaceable>
is specified, only those extensions whose names match the pattern
are listed.
If the form <literal>\dx+</literal> is used, all the objects belonging
to each matching extension are listed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dy[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists event triggers.
If <replaceable class="parameter">pattern</replaceable>
is specified, only those event triggers whose names match the pattern
are listed.
If <literal>+</literal> is appended to the command name, each object
is listed with its associated description.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\e</literal> or <literal>\edit</> <literal> <optional> <replaceable class="parameter">filename</> </optional> <optional> <replaceable class="parameter">line_number</> </optional> </literal></term>
<listitem>
<para>
If <replaceable class="parameter">filename</replaceable> is
specified, the file is edited; after the editor exits, its
content is copied back to the query buffer. If no <replaceable
class="parameter">filename</replaceable> is given, the current query
buffer is copied to a temporary file which is then edited in the same
fashion.
</para>
<para>
The new query buffer is then re-parsed according to the normal
rules of <application>psql</application>, where the whole buffer
is treated as a single line. (Thus you cannot make scripts this
way. Use <command>\i</command> for that.) This means that
if the query ends with (or contains) a semicolon, it is
immediately executed. Otherwise it will merely wait in the
query buffer; type semicolon or <literal>\g</> to send it, or
<literal>\r</> to cancel.
</para>
<para>
If a line number is specified, <application>psql</application> will
position the cursor on the specified line of the file or query buffer.
Note that if a single all-digits argument is given,
<application>psql</application> assumes it is a line number,
not a file name.
</para>
<tip>
<para>
See under <xref linkend="app-psql-environment"
endterm="app-psql-environment-title"> for how to configure and
customize your editor.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\echo <replaceable class="parameter">text</replaceable> [ ... ]</literal></term>
<listitem>
<para>
Prints the arguments to the standard output, separated by one
space and followed by a newline. This can be useful to
intersperse information in the output of scripts. For example:
<programlisting>
=&gt; <userinput>\echo `date`</userinput>
Tue Oct 26 21:40:57 CEST 1999
</programlisting>
If the first argument is an unquoted <literal>-n</literal> the trailing
newline is not written.
</para>
<tip>
<para>
If you use the <command>\o</command> command to redirect your
query output you might wish to use <command>\qecho</command>
instead of this command.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ef <optional> <replaceable class="parameter">function_description</> <optional> <replaceable class="parameter">line_number</> </optional> </optional> </literal></term>
<listitem>
<para>
This command fetches and edits the definition of the named function,
in the form of a <command>CREATE OR REPLACE FUNCTION</> command.
Editing is done in the same way as for <literal>\edit</>.
After the editor exits, the updated command waits in the query buffer;
type semicolon or <literal>\g</> to send it, or <literal>\r</>
to cancel.
</para>
<para>
The target function can be specified by name alone, or by name
and arguments, for example <literal>foo(integer, text)</>.
The argument types must be given if there is more
than one function of the same name.
</para>
<para>
If no function is specified, a blank <command>CREATE FUNCTION</>
template is presented for editing.
</para>
<para>
If a line number is specified, <application>psql</application> will
position the cursor on the specified line of the function body.
(Note that the function body typically does not begin on the first
line of the file.)
</para>
<tip>
<para>
See under <xref linkend="app-psql-environment"
endterm="app-psql-environment-title"> for how to configure and
customize your editor.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\encoding [ <replaceable class="parameter">encoding</replaceable> ]</literal></term>
<listitem>
<para>
Sets the client character set encoding. Without an argument, this command
shows the current encoding.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\f [ <replaceable class="parameter">string</replaceable> ]</literal></term>
<listitem>
<para>
Sets the field separator for unaligned query output. The default
is the vertical bar (<literal>|</literal>). See also
<command>\pset</command> for a generic way of setting output
options.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\g [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
<term><literal>\g [ |<replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
Sends the current query input buffer to the server, and
optionally stores the query's output in <replaceable
class="parameter">filename</replaceable> or pipes the output
to the shell command <replaceable
class="parameter">command</replaceable>. The file or command is
written to only if the query successfully returns zero or more tuples,
not if the query fails or is a non-data-returning SQL command.
</para>
<para>
A bare <literal>\g</literal> is essentially equivalent to a semicolon.
A <literal>\g</literal> with argument is a <quote>one-shot</quote>
alternative to the <command>\o</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\gset [ <replaceable class="parameter">prefix</replaceable> ]</literal></term>
<listitem>
<para>
Sends the current query input buffer to the server and stores the
query's output into <application>psql</> variables (see <xref
linkend="APP-PSQL-variables" endterm="APP-PSQL-variables-title">).
The query to be executed must return exactly one row. Each column of
the row is stored into a separate variable, named the same as the
column. For example:
<programlisting>
=&gt; <userinput>SELECT 'hello' AS var1, 10 AS var2</userinput>
-&gt; <userinput>\gset</userinput>
=&gt; <userinput>\echo :var1 :var2</userinput>
hello 10
</programlisting>
</para>
<para>
If you specify a <replaceable class="parameter">prefix</replaceable>,
that string is prepended to the query's column names to create the
variable names to use:
<programlisting>
=&gt; <userinput>SELECT 'hello' AS var1, 10 AS var2</userinput>
-&gt; <userinput>\gset result_</userinput>
=&gt; <userinput>\echo :result_var1 :result_var2</userinput>
hello 10
</programlisting>
</para>
<para>
If a column result is NULL, the corresponding variable is unset
rather than being set.
</para>
<para>
If the query fails or does not return one row,
no variables are changed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\h</literal> or <literal>\help</literal> <literal>[ <replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
Gives syntax help on the specified <acronym>SQL</acronym>
command. If <replaceable class="parameter">command</replaceable>
is not specified, then <application>psql</application> will list
all the commands for which syntax help is available. If
<replaceable class="parameter">command</replaceable> is an
asterisk (<literal>*</literal>), then syntax help on all
<acronym>SQL</acronym> commands is shown.
</para>
<note>
<para>
To simplify typing, commands that consists of several words do
not have to be quoted. Thus it is fine to type <userinput>\help
alter table</userinput>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\H</literal> or <literal>\html</literal></term>
<listitem>
<para>
Turns on <acronym>HTML</acronym> query output format. If the
<acronym>HTML</acronym> format is already on, it is switched
back to the default aligned text format. This command is for
compatibility and convenience, but see <command>\pset</command>
about setting other output options.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\i</literal> or <literal>\include</literal> <replaceable class="parameter">filename</replaceable></term>
<listitem>
<para>
Reads input from the file <replaceable
class="parameter">filename</replaceable> and executes it as
though it had been typed on the keyboard.
</para>
<para>
If <replaceable>filename</replaceable> is <literal>-</literal>
(hyphen), then standard input is read until an EOF indication
or <command>\q</> meta-command. This can be used to intersperse
interactive input with input from files. Note that Readline behavior
will be used only if it is active at the outermost level.
</para>
<note>
<para>
If you want to see the lines on the screen as they are read you
must set the variable <varname>ECHO</varname> to
<literal>all</literal>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ir</literal> or <literal>\include_relative</literal> <replaceable class="parameter">filename</replaceable></term>
<listitem>
<para>
The <literal>\ir</> command is similar to <literal>\i</>, but resolves
relative file names differently. When executing in interactive mode,
the two commands behave identically. However, when invoked from a
script, <literal>\ir</literal> interprets file names relative to the
directory in which the script is located, rather than the current
working directory.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\l[+]</literal> or <literal>\list[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
List the databases in the server and show their names, owners,
character set encodings, and access privileges.
If <replaceable class="parameter">pattern</replaceable> is specified,
only databases whose names match the pattern are listed.
If <literal>+</literal> is appended to the command name, database
sizes, default tablespaces, and descriptions are also displayed.
(Size information is only available for databases that the current
user can connect to.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\lo_export <replaceable class="parameter">loid</replaceable> <replaceable class="parameter">filename</replaceable></literal></term>
<listitem>
<para>
Reads the large object with <acronym>OID</acronym> <replaceable
class="parameter">loid</replaceable> from the database and
writes it to <replaceable
class="parameter">filename</replaceable>. Note that this is
subtly different from the server function
<function>lo_export</function>, which acts with the permissions
of the user that the database server runs as and on the server's
file system.
</para>
<tip>
<para>
Use <command>\lo_list</command> to find out the large object's
<acronym>OID</acronym>.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\lo_import <replaceable class="parameter">filename</replaceable> [ <replaceable class="parameter">comment</replaceable> ]</literal></term>
<listitem>
<para>
Stores the file into a <productname>PostgreSQL</productname>
large object. Optionally, it associates the given
comment with the object. Example:
<programlisting>
foo=&gt; <userinput>\lo_import '/home/peter/pictures/photo.xcf' 'a picture of me'</userinput>
lo_import 152801
</programlisting>
The response indicates that the large object received object
ID 152801, which can be used to access the newly-created large
object in the future. For the sake of readability, it is
recommended to always associate a human-readable comment with
every object. Both OIDs and comments can be viewed with the
<command>\lo_list</command> command.
</para>
<para>
Note that this command is subtly different from the server-side
<function>lo_import</function> because it acts as the local user
on the local file system, rather than the server's user and file
system.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\lo_list</literal></term>
<listitem>
<para>
Shows a list of all <productname>PostgreSQL</productname>
large objects currently stored in the database,
along with any comments provided for them.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\lo_unlink <replaceable class="parameter">loid</replaceable></literal></term>
<listitem>
<para>
Deletes the large object with <acronym>OID</acronym>
<replaceable class="parameter">loid</replaceable> from the
database.
</para>
<tip>
<para>
Use <command>\lo_list</command> to find out the large object's
<acronym>OID</acronym>.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\o</literal> or <literal>\out [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
<term><literal>\o</literal> or <literal>\out [ |<replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
Arranges to save future query results to the file <replaceable
class="parameter">filename</replaceable> or pipe future results
to the shell command <replaceable
class="parameter">command</replaceable>. If no argument is
specified, the query output is reset to the standard output.
</para>
<para><quote>Query results</quote> includes all tables, command
responses, and notices obtained from the database server, as
well as output of various backslash commands that query the
database (such as <command>\d</command>), but not error
messages.
</para>
<tip>
<para>
To intersperse text output in between query results, use
<command>\qecho</command>.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\p</literal> or <literal>\print</literal></term>
<listitem>
<para>
Print the current query buffer to the standard output.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\password [ <replaceable class="parameter">username</replaceable> ]</literal></term>
<listitem>
<para>
Changes the password of the specified user (by default, the current
user). This command prompts for the new password, encrypts it, and
sends it to the server as an <command>ALTER ROLE</> command. This
makes sure that the new password does not appear in cleartext in the
command history, the server log, or elsewhere.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\prompt [ <replaceable class="parameter">text</replaceable> ] <replaceable class="parameter">name</replaceable></literal></term>
<listitem>
<para>
Prompts the user to supply text, which is assigned to the variable
<replaceable class="parameter">name</>.
An optional prompt string, <replaceable
class="parameter">text</>, can be specified. (For multiword
prompts, surround the text with single quotes.)
</para>
<para>
By default, <literal>\prompt</> uses the terminal for input and
output. However, if the <option>-f</> command line switch was
used, <literal>\prompt</> uses standard input and standard output.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\pset [ <replaceable class="parameter">option</replaceable> [ <replaceable class="parameter">value</replaceable> ] ]</literal></term>
<listitem>
<para>
This command sets options affecting the output of query result tables.
<replaceable class="parameter">option</replaceable>
indicates which option is to be set. The semantics of
<replaceable class="parameter">value</replaceable> vary depending
on the selected option. For some options, omitting <replaceable
class="parameter">value</replaceable> causes the option to be toggled
or unset, as described under the particular option. If no such
behavior is mentioned, then omitting
<replaceable class="parameter">value</replaceable> just results in
the current setting being displayed.
</para>
<para>
<command>\pset</command> without any arguments displays the current status
of all printing options.
</para>
<para>
Adjustable printing options are:
<variablelist>
<varlistentry>
<term><literal>border</literal></term>
<listitem>
<para>
The <replaceable class="parameter">value</replaceable> must be a
number. In general, the higher
the number the more borders and lines the tables will have,
but details depend on the particular format.
In <acronym>HTML</acronym> format, this will translate directly
into the <literal>border=...</literal> attribute.
In most other formats only values 0 (no border), 1 (internal
dividing lines), and 2 (table frame) make sense, and values above 2
will be treated the same as <literal>border = 2</literal>.
The <literal>latex</literal> and <literal>latex-longtable</literal>
formats additionally allow a value of 3 to add dividing lines
between data rows.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>columns</literal></term>
<listitem>
<para>
Sets the target width for the <literal>wrapped</> format, and also
the width limit for determining whether output is wide enough to
require the pager or switch to the vertical display in expanded auto
mode.
Zero (the default) causes the target width to be controlled by the
environment variable <envar>COLUMNS</>, or the detected screen width
if <envar>COLUMNS</> is not set.
In addition, if <literal>columns</> is zero then the
<literal>wrapped</> format only affects screen output.
If <literal>columns</> is nonzero then file and pipe output is
wrapped to that width as well.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>expanded</literal> (or <literal>x</literal>)</term>
<listitem>
<para>
If <replaceable class="parameter">value</replaceable> is specified it
must be either <literal>on</literal> or <literal>off</literal>, which
will enable or disable expanded mode, or <literal>auto</literal>.
If <replaceable class="parameter">value</replaceable> is omitted the
command toggles between the on and off settings. When expanded mode
is enabled, query results are displayed in two columns, with the
column name on the left and the data on the right. This mode is
useful if the data wouldn't fit on the screen in the
normal <quote>horizontal</quote> mode. In the auto setting, the
expanded mode is used whenever the query output is wider than the
screen, otherwise the regular mode is used. The auto setting is only
effective in the aligned and wrapped formats. In other formats, it
always behaves as if the expanded mode is off.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>fieldsep</literal></term>
<listitem>
<para>
Specifies the field separator to be used in unaligned output
format. That way one can create, for example, tab- or
comma-separated output, which other programs might prefer. To
set a tab as field separator, type <literal>\pset fieldsep
'\t'</literal>. The default field separator is
<literal>'|'</literal> (a vertical bar).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>fieldsep_zero</literal></term>
<listitem>
<para>
Sets the field separator to use in unaligned output format to a zero
byte.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>footer</literal></term>
<listitem>
<para>
If <replaceable class="parameter">value</replaceable> is specified
it must be either <literal>on</literal> or <literal>off</literal>
which will enable or disable display of the table footer
(the <literal>(<replaceable>n</> rows)</literal> count).
If <replaceable class="parameter">value</replaceable> is omitted the
command toggles footer display on or off.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>format</literal></term>
<listitem>
<para>
Sets the output format to one of <literal>unaligned</literal>,
<literal>aligned</literal>, <literal>wrapped</literal>,
<literal>html</literal>, <literal>asciidoc</literal>,
<literal>latex</literal> (uses <literal>tabular</literal>),
<literal>latex-longtable</literal>, or
<literal>troff-ms</literal>.
Unique abbreviations are allowed. (That would mean one letter
is enough.)
</para>
<para><literal>unaligned</> format writes all columns of a row on one
line, separated by the currently active field separator. This
is useful for creating output that might be intended to be read
in by other programs (for example, tab-separated or comma-separated
format).
</para>
<para><literal>aligned</literal> format is the standard, human-readable,
nicely formatted text output; this is the default.
</para>
<para><literal>wrapped</> format is like <literal>aligned</> but wraps
wide data values across lines to make the output fit in the target
column width. The target width is determined as described under
the <literal>columns</> option. Note that <application>psql</> will
not attempt to wrap column header titles; therefore,
<literal>wrapped</> format behaves the same as <literal>aligned</>
if the total width needed for column headers exceeds the target.
</para>
<para>
The <literal>html</>, <literal>asciidoc</>, <literal>latex</>,
<literal>latex-longtable</literal>, and <literal>troff-ms</>
formats put out tables that are intended to
be included in documents using the respective mark-up
language. They are not complete documents! This might not be
necessary in <acronym>HTML</acronym>, but in
<application>LaTeX</application> you must have a complete
document wrapper. <literal>latex-longtable</literal>
also requires the <application>LaTeX</application>
<literal>longtable</literal> and <literal>booktabs</> packages.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>linestyle</literal></term>
<listitem>
<para>
Sets the border line drawing style to one
of <literal>ascii</literal>, <literal>old-ascii</literal>
or <literal>unicode</literal>.
Unique abbreviations are allowed. (That would mean one
letter is enough.)
The default setting is <literal>ascii</>.
This option only affects the <literal>aligned</> and
<literal>wrapped</> output formats.
</para>
<para><literal>ascii</literal> style uses plain <acronym>ASCII</acronym>
characters. Newlines in data are shown using
a <literal>+</literal> symbol in the right-hand margin.
When the <literal>wrapped</literal> format wraps data from
one line to the next without a newline character, a dot
(<literal>.</>) is shown in the right-hand margin of the first line,
and again in the left-hand margin of the following line.
</para>
<para><literal>old-ascii</literal> style uses plain <acronym>ASCII</>
characters, using the formatting style used
in <productname>PostgreSQL</productname> 8.4 and earlier.
Newlines in data are shown using a <literal>:</literal>
symbol in place of the left-hand column separator.
When the data is wrapped from one line
to the next without a newline character, a <literal>;</>
symbol is used in place of the left-hand column separator.
</para>
<para><literal>unicode</literal> style uses Unicode box-drawing characters.
Newlines in data are shown using a carriage return symbol
in the right-hand margin. When the data is wrapped from one line
to the next without a newline character, an ellipsis symbol
is shown in the right-hand margin of the first line, and
again in the left-hand margin of the following line.
</para>
<para>
When the <literal>border</> setting is greater than zero,
the <literal>linestyle</literal> option also determines the
characters with which the border lines are drawn.
Plain <acronym>ASCII</acronym> characters work everywhere, but
Unicode characters look nicer on displays that recognize them.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>null</literal></term>
<listitem>
<para>
Sets the string to be printed in place of a null value.
The default is to print nothing, which can easily be mistaken for
an empty string. For example, one might prefer <literal>\pset null
'(null)'</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>numericlocale</literal></term>
<listitem>
<para>
If <replaceable class="parameter">value</replaceable> is specified
it must be either <literal>on</literal> or <literal>off</literal>
which will enable or disable display of a locale-specific character
to separate groups of digits to the left of the decimal marker.
If <replaceable class="parameter">value</replaceable> is omitted the
command toggles between regular and locale-specific numeric output.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>pager</literal></term>
<listitem>
<para>
Controls use of a pager program for query and <application>psql</>
help output. If the environment variable <envar>PAGER</envar>
is set, the output is piped to the specified program.
Otherwise a platform-dependent default (such as
<filename>more</filename>) is used.
</para>
<para>
When the <literal>pager</> option is <literal>off</>, the pager
program is not used. When the <literal>pager</> option is
<literal>on</>, the pager is used when appropriate, i.e., when the
output is to a terminal and will not fit on the screen.
The <literal>pager</> option can also be set to <literal>always</>,
which causes the pager to be used for all terminal output regardless
of whether it fits on the screen. <literal>\pset pager</>
without a <replaceable class="parameter">value</replaceable>
toggles pager use on and off.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>pager_min_lines</literal></term>
<listitem>
<para>
If <literal>pager_min_lines</> is set to a number greater than the
page height, the pager program will not be called unless there are
at least this many lines of output to show. The default setting
is 0.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>recordsep</literal></term>
<listitem>
<para>
Specifies the record (line) separator to use in unaligned
output format. The default is a newline character.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>recordsep_zero</literal></term>
<listitem>
<para>
Sets the record separator to use in unaligned output format to a zero
byte.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>tableattr</literal> (or <literal>T</literal>)</term>
<listitem>
<para>
In <acronym>HTML</acronym> format, this specifies attributes
to be placed inside the <sgmltag>table</sgmltag> tag. This
could for example be <literal>cellpadding</literal> or
<literal>bgcolor</literal>. Note that you probably don't want
to specify <literal>border</literal> here, as that is already
taken care of by <literal>\pset border</literal>.
If no
<replaceable class="parameter">value</replaceable> is given,
the table attributes are unset.
</para>
<para>
In <literal>latex-longtable</literal> format, this controls
the proportional width of each column containing a left-aligned
data type. It is specified as a whitespace-separated list of values,
e.g. <literal>'0.2 0.2 0.6'</>. Unspecified output columns
use the last specified value.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>title</literal></term>
<listitem>
<para>
Sets the table title for any subsequently printed tables. This
can be used to give your output descriptive tags. If no
<replaceable class="parameter">value</replaceable> is given,
the title is unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>tuples_only</literal> (or <literal>t</literal>)</term>
<listitem>
<para>
If <replaceable class="parameter">value</replaceable> is specified
it must be either <literal>on</literal> or <literal>off</literal>
which will enable or disable tuples-only mode.
If <replaceable class="parameter">value</replaceable> is omitted the
command toggles between regular and tuples-only output.
Regular output includes extra information such
as column headers, titles, and various footers. In tuples-only
mode, only actual table data is shown.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>unicode_border_linestyle</literal></term>
<listitem>
<para>
Sets the border drawing style for the <literal>unicode</literal>
line style to one of <literal>single</literal>
or <literal>double</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>unicode_column_linestyle</literal></term>
<listitem>
<para>
Sets the column drawing style for the <literal>unicode</literal>
line style to one of <literal>single</literal>
or <literal>double</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>unicode_header_linestyle</literal></term>
<listitem>
<para>
Sets the header drawing style for the <literal>unicode</literal>
line style to one of <literal>single</literal>
or <literal>double</literal>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
Illustrations of how these different formats look can be seen in
the <xref linkend="APP-PSQL-examples"
endterm="APP-PSQL-examples-title"> section.
</para>
<tip>
<para>
There are various shortcut commands for <command>\pset</command>. See
<command>\a</command>, <command>\C</command>, <command>\f</command>,
<command>\H</command>, <command>\t</command>, <command>\T</command>,
and <command>\x</command>.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\q</literal> or <literal>\quit</literal></term>
<listitem>
<para>
Quits the <application>psql</application> program.
In a script file, only execution of that script is terminated.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\qecho <replaceable class="parameter">text</replaceable> [ ... ] </literal></term>
<listitem>
<para>
This command is identical to <command>\echo</command> except
that the output will be written to the query output channel, as
set by <command>\o</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\r</literal> or <literal>\reset</literal></term>
<listitem>
<para>
Resets (clears) the query buffer.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\s [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
<listitem>
<para>
Print <application>psql</application>'s command line history
to <replaceable class="parameter">filename</replaceable>.
If <replaceable class="parameter">filename</replaceable> is omitted,
the history is written to the standard output (using the pager if
appropriate). This command is not available
if <application>psql</application> was built
without <application>Readline</application> support.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\set [ <replaceable class="parameter">name</replaceable> [ <replaceable class="parameter">value</replaceable> [ ... ] ] ]</literal></term>
<listitem>
<para>
Sets the <application>psql</> variable <replaceable
class="parameter">name</replaceable> to <replaceable
class="parameter">value</replaceable>, or if more than one value
is given, to the concatenation of all of them. If only one
argument is given, the variable is set with an empty value. To
unset a variable, use the <command>\unset</command> command.
</para>
<para><command>\set</> without any arguments displays the names and values
of all currently-set <application>psql</> variables.
</para>
<para>
Valid variable names can contain letters, digits, and
underscores. See the section <xref
linkend="APP-PSQL-variables"
endterm="APP-PSQL-variables-title"> below for details.
Variable names are case-sensitive.
</para>
<para>
Although you are welcome to set any variable to anything you
want, <application>psql</application> treats several variables
as special. They are documented in the section about variables.
</para>
<note>
<para>
This command is unrelated to the <acronym>SQL</acronym>
command <xref linkend="SQL-SET">.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\setenv <replaceable class="parameter">name</replaceable> [ <replaceable class="parameter">value</replaceable> ]</literal></term>
<listitem>
<para>
Sets the environment variable <replaceable
class="parameter">name</replaceable> to <replaceable
class="parameter">value</replaceable>, or if the
<replaceable class="parameter">value</replaceable> is
not supplied, unsets the environment variable. Example:
<programlisting>
testdb=&gt; <userinput>\setenv PAGER less</userinput>
testdb=&gt; <userinput>\setenv LESS -imx4F</userinput>
</programlisting></para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\sf[+] <replaceable class="parameter">function_description</> </literal></term>
<listitem>
<para>
This command fetches and shows the definition of the named function,
in the form of a <command>CREATE OR REPLACE FUNCTION</> command.
The definition is printed to the current query output channel,
as set by <command>\o</command>.
</para>
<para>
The target function can be specified by name alone, or by name
and arguments, for example <literal>foo(integer, text)</>.
The argument types must be given if there is more
than one function of the same name.
</para>
<para>
If <literal>+</literal> is appended to the command name, then the
output lines are numbered, with the first line of the function body
being line 1.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\t</literal></term>
<listitem>
<para>
Toggles the display of output column name headings and row count
footer. This command is equivalent to <literal>\pset
tuples_only</literal> and is provided for convenience.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\T <replaceable class="parameter">table_options</replaceable></literal></term>
<listitem>
<para>
Specifies attributes to be placed within the
<sgmltag>table</sgmltag> tag in <acronym>HTML</acronym>
output format. This command is equivalent to <literal>\pset
tableattr <replaceable
class="parameter">table_options</replaceable></literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\timing [ <replaceable class="parameter">on</replaceable> | <replaceable class="parameter">off</replaceable> ]</literal></term>
<listitem>
<para>
Without parameter, toggles a display of how long each SQL statement
takes, in milliseconds. With parameter, sets same.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\unset <replaceable class="parameter">name</replaceable></literal></term>
<listitem>
<para>
Unsets (deletes) the <application>psql</> variable <replaceable
class="parameter">name</replaceable>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\w</literal> or <literal>\write</literal> <replaceable class="parameter">filename</replaceable></term>
<term><literal>\w</literal> or <literal>\write</literal> <literal>|</><replaceable class="parameter">command</replaceable></term>
<listitem>
<para>
Outputs the current query buffer to the file <replaceable
class="parameter">filename</replaceable> or pipes it to the shell
command <replaceable class="parameter">command</replaceable>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\watch [ <replaceable class="parameter">seconds</replaceable> ]</literal></term>
<listitem>
<para>
Repeatedly execute the current query buffer (like <literal>\g</>)
until interrupted or the query fails. Wait the specified number of
seconds (default 2) between executions.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\x [ <replaceable class="parameter">on</replaceable> | <replaceable class="parameter">off</replaceable> | <replaceable class="parameter">auto</replaceable> ]</literal></term>
<listitem>
<para>
Sets or toggles expanded table formatting mode. As such it is equivalent to
<literal>\pset expanded</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\z [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists tables, views and sequences with their
associated access privileges.
If a <replaceable class="parameter">pattern</replaceable> is
specified, only tables, views and sequences whose names match the
pattern are listed.
</para>
<para>
This is an alias for <command>\dp</command> (<quote>display
privileges</quote>).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\! [ <replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
Escapes to a separate shell or executes the shell command
<replaceable class="parameter">command</replaceable>. The
arguments are not further interpreted; the shell will see them
as-is. In particular, the variable substitution rules and
backslash escapes do not apply.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\? [ <replaceable class="parameter">topic</> ]</literal></term>
<listitem>
<para>
Shows help information. The optional
<replaceable class="parameter">topic</> parameter
(defaulting to <literal>commands</>) selects which part of <application>psql</application> is
explained: <literal>commands</> describes <application>psql</>'s
backslash commands; <literal>options</> describes the command-line
options that can be passed to <application>psql</>;
and <literal>variables</> shows help about <application>psql</application> configuration
variables.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<refsect3 id="APP-PSQL-patterns">
<title id="APP-PSQL-patterns-title">Patterns</title>
<indexterm>
<primary>patterns</primary>
<secondary>in psql and pg_dump</secondary>
</indexterm>
<para>
The various <literal>\d</> commands accept a <replaceable
class="parameter">pattern</replaceable> parameter to specify the
object name(s) to be displayed. In the simplest case, a pattern
is just the exact name of the object. The characters within a
pattern are normally folded to lower case, just as in SQL names;
for example, <literal>\dt FOO</> will display the table named
<literal>foo</>. As in SQL names, placing double quotes around
a pattern stops folding to lower case. Should you need to include
an actual double quote character in a pattern, write it as a pair
of double quotes within a double-quote sequence; again this is in
accord with the rules for SQL quoted identifiers. For example,
<literal>\dt "FOO""BAR"</> will display the table named
<literal>FOO"BAR</> (not <literal>foo"bar</>). Unlike the normal
rules for SQL names, you can put double quotes around just part
of a pattern, for instance <literal>\dt FOO"FOO"BAR</> will display
the table named <literal>fooFOObar</>.
</para>
<para>
Whenever the <replaceable class="parameter">pattern</replaceable> parameter
is omitted completely, the <literal>\d</> commands display all objects
that are visible in the current schema search path &mdash; this is
equivalent to using <literal>*</> as the pattern.
(An object is said to be <firstterm>visible</> if its
containing schema is in the search path and no object of the same
kind and name appears earlier in the search path. This is equivalent to the
statement that the object can be referenced by name without explicit
schema qualification.)
To see all objects in the database regardless of visibility,
use <literal>*.*</> as the pattern.
</para>
<para>
Within a pattern, <literal>*</> matches any sequence of characters
(including no characters) and <literal>?</> matches any single character.
(This notation is comparable to Unix shell file name patterns.)
For example, <literal>\dt int*</> displays tables whose names
begin with <literal>int</>. But within double quotes, <literal>*</>
and <literal>?</> lose these special meanings and are just matched
literally.
</para>
<para>
A pattern that contains a dot (<literal>.</>) is interpreted as a schema
name pattern followed by an object name pattern. For example,
<literal>\dt foo*.*bar*</> displays all tables whose table name
includes <literal>bar</> that are in schemas whose schema name
starts with <literal>foo</>. When no dot appears, then the pattern
matches only objects that are visible in the current schema search path.
Again, a dot within double quotes loses its special meaning and is matched
literally.
</para>
<para>
Advanced users can use regular-expression notations such as character
classes, for example <literal>[0-9]</> to match any digit. All regular
expression special characters work as specified in
<xref linkend="functions-posix-regexp">, except for <literal>.</> which
is taken as a separator as mentioned above, <literal>*</> which is
translated to the regular-expression notation <literal>.*</>,
<literal>?</> which is translated to <literal>.</>, and
<literal>$</> which is matched literally. You can emulate
these pattern characters at need by writing
<literal>?</> for <literal>.</>,
<literal>(<replaceable class="parameter">R</replaceable>+|)</literal> for
<literal><replaceable class="parameter">R</replaceable>*</literal>, or
<literal>(<replaceable class="parameter">R</replaceable>|)</literal> for
<literal><replaceable class="parameter">R</replaceable>?</literal>.
<literal>$</> is not needed as a regular-expression character since
the pattern must match the whole name, unlike the usual
interpretation of regular expressions (in other words, <literal>$</>
is automatically appended to your pattern). Write <literal>*</> at the
beginning and/or end if you don't wish the pattern to be anchored.
Note that within double quotes, all regular expression special characters
lose their special meanings and are matched literally. Also, the regular
expression special characters are matched literally in operator name
patterns (i.e., the argument of <literal>\do</>).
</para>
</refsect3>
</refsect2>
<refsect2>
<title>Advanced Features</title>
<refsect3 id="APP-PSQL-variables">
<title id="APP-PSQL-variables-title">Variables</title>
<para>
<application>psql</application> provides variable substitution
features similar to common Unix command shells.
Variables are simply name/value pairs, where the value
can be any string of any length. The name must consist of letters
(including non-Latin letters), digits, and underscores.
</para>
<para>
To set a variable, use the <application>psql</application> meta-command
<command>\set</command>. For example,
<programlisting>
testdb=&gt; <userinput>\set foo bar</userinput>
</programlisting>
sets the variable <literal>foo</literal> to the value
<literal>bar</literal>. To retrieve the content of the variable, precede
the name with a colon, for example:
<programlisting>
testdb=&gt; <userinput>\echo :foo</userinput>
bar
</programlisting>
This works in both regular SQL commands and meta-commands; there is
more detail in <xref linkend="APP-PSQL-interpolation"
endterm="APP-PSQL-interpolation-title">, below.
</para>
<para>
If you call <command>\set</command> without a second argument, the
variable is set, with an empty string as value. To unset (i.e., delete)
a variable, use the command <command>\unset</command>. To show the
values of all variables, call <command>\set</command> without any argument.
</para>
<note>
<para>
The arguments of <command>\set</command> are subject to the same
substitution rules as with other commands. Thus you can construct
interesting references such as <literal>\set :foo
'something'</literal> and get <quote>soft links</quote> or
<quote>variable variables</quote> of <productname>Perl</productname>
or <productname><acronym>PHP</acronym></productname> fame,
respectively. Unfortunately (or fortunately?), there is no way to do
anything useful with these constructs. On the other hand,
<literal>\set bar :foo</literal> is a perfectly valid way to copy a
variable.
</para>
</note>
<para>
A number of these variables are treated specially
by <application>psql</application>. They represent certain option
settings that can be changed at run time by altering the value of
the variable, or in some cases represent changeable state of
<application>psql</application>. Although
you can use these variables for other purposes, this is not
recommended, as the program behavior might grow really strange
really quickly. By convention, all specially treated variables' names
consist of all upper-case ASCII letters (and possibly digits and
underscores). To ensure maximum compatibility in the future, avoid
using such variable names for your own purposes. A list of all specially
treated variables follows.
</para>
<variablelist>
<varlistentry>
<term>
<varname>AUTOCOMMIT</varname>
<indexterm>
<primary>autocommit</primary>
<secondary>psql</secondary>
</indexterm>
</term>
<listitem>
<para>
When <literal>on</> (the default), each SQL command is automatically
committed upon successful completion. To postpone commit in this
mode, you must enter a <command>BEGIN</> or <command>START
TRANSACTION</> SQL command. When <literal>off</> or unset, SQL
commands are not committed until you explicitly issue
<command>COMMIT</> or <command>END</>. The autocommit-off
mode works by issuing an implicit <command>BEGIN</> for you, just
before any command that is not already in a transaction block and
is not itself a <command>BEGIN</> or other transaction-control
command, nor a command that cannot be executed inside a transaction
block (such as <command>VACUUM</>).
</para>
<note>
<para>
In autocommit-off mode, you must explicitly abandon any failed
transaction by entering <command>ABORT</> or <command>ROLLBACK</>.
Also keep in mind that if you exit the session
without committing, your work will be lost.
</para>
</note>
<note>
<para>
The autocommit-on mode is <productname>PostgreSQL</>'s traditional
behavior, but autocommit-off is closer to the SQL spec. If you
prefer autocommit-off, you might wish to set it in the system-wide
<filename>psqlrc</filename> file or your
<filename>~/.psqlrc</filename> file.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>COMP_KEYWORD_CASE</varname></term>
<listitem>
<para>
Determines which letter case to use when completing an SQL key word.
If set to <literal>lower</literal> or <literal>upper</literal>, the
completed word will be in lower or upper case, respectively. If set
to <literal>preserve-lower</literal>
or <literal>preserve-upper</literal> (the default), the completed word
will be in the case of the word already entered, but words being
completed without anything entered will be in lower or upper case,
respectively.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>DBNAME</varname></term>
<listitem>
<para>
The name of the database you are currently connected to. This is
set every time you connect to a database (including program
start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ECHO</varname></term>
<listitem>
<para>
If set to <literal>all</literal>, all nonempty input lines are printed
to standard output as they are read. (This does not apply to lines
read interactively.) To select this behavior on program
start-up, use the switch <option>-a</option>. If set to
<literal>queries</literal>,
<application>psql</application> prints each query to standard output
as it is sent to the server. The switch for this is
<option>-e</option>. If set to <literal>errors</literal>, then only
failed queries are displayed on standard error output. The switch
for this is <option>-b</option>. If unset, or if set to
<literal>none</literal> (or any other value than those above) then
no queries are displayed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ECHO_HIDDEN</varname></term>
<listitem>
<para>
When this variable is set to <literal>on</> and a backslash command
queries the database, the query is first shown.
This feature helps you to study
<productname>PostgreSQL</productname> internals and provide
similar functionality in your own programs. (To select this behavior
on program start-up, use the switch <option>-E</option>.) If you set
the variable to the value <literal>noexec</literal>, the queries are
just shown but are not actually sent to the server and executed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ENCODING</varname></term>
<listitem>
<para>
The current client character set encoding.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>FETCH_COUNT</varname></term>
<listitem>
<para>
If this variable is set to an integer value &gt; 0,
the results of <command>SELECT</command> queries are fetched
and displayed in groups of that many rows, rather than the
default behavior of collecting the entire result set before
display. Therefore only a
limited amount of memory is used, regardless of the size of
the result set. Settings of 100 to 1000 are commonly used
when enabling this feature.
Keep in mind that when using this feature, a query might
fail after having already displayed some rows.
</para>
<tip>
<para>
Although you can use any output format with this feature,
the default <literal>aligned</> format tends to look bad
because each group of <varname>FETCH_COUNT</varname> rows
will be formatted separately, leading to varying column
widths across the row groups. The other output formats work better.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HISTCONTROL</varname></term>
<listitem>
<para>
If this variable is set to <literal>ignorespace</literal>,
lines which begin with a space are not entered into the history
list. If set to a value of <literal>ignoredups</literal>, lines
matching the previous history line are not entered. A value of
<literal>ignoreboth</literal> combines the two options. If
unset, or if set to <literal>none</literal> (or any other value
than those above), all lines read in interactive mode are
saved on the history list.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HISTFILE</varname></term>
<listitem>
<para>
The file name that will be used to store the history list. The default
value is <filename>~/.psql_history</filename>. For example, putting:
<programlisting>
\set HISTFILE ~/.psql_history- :DBNAME
</programlisting>
in <filename>~/.psqlrc</filename> will cause
<application>psql</application> to maintain a separate history for
each database.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HISTSIZE</varname></term>
<listitem>
<para>
The number of commands to store in the command history. The
default value is 500.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HOST</varname></term>
<listitem>
<para>
The database server host you are currently connected to. This is
set every time you connect to a database (including program
start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>IGNOREEOF</varname></term>
<listitem>
<para>
If unset, sending an <acronym>EOF</> character (usually
<keycombo action="simul"><keycap>Control</><keycap>D</></>)
to an interactive session of <application>psql</application>
will terminate the application. If set to a numeric value,
that many <acronym>EOF</> characters are ignored before the
application terminates. If the variable is set but has no
numeric value, the default is 10.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>LASTOID</varname></term>
<listitem>
<para>
The value of the last affected OID, as returned from an
<command>INSERT</command> or <command>\lo_import</command>
command. This variable is only guaranteed to be valid until
after the result of the next <acronym>SQL</acronym> command has
been displayed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<varname>ON_ERROR_ROLLBACK</varname>
<indexterm>
<primary>rollback</primary>
<secondary>psql</secondary>
</indexterm>
</term>
<listitem>
<para>
When set to <literal>on</>, if a statement in a transaction block
generates an error, the error is ignored and the transaction
continues. When set to <literal>interactive</>, such errors are only
ignored in interactive sessions, and not when reading script
files. When unset or set to <literal>off</>, a statement in a
transaction block that generates an error aborts the entire
transaction. The error rollback mode works by issuing an
implicit <command>SAVEPOINT</> for you, just before each command
that is in a transaction block, and then rolling back to the
savepoint if the command fails.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ON_ERROR_STOP</varname></term>
<listitem>
<para>
By default, command processing continues after an error. When this
variable is set to <literal>on</>, processing will instead stop
immediately. In interactive mode,
<application>psql</application> will return to the command prompt;
otherwise, <application>psql</application> will exit, returning
error code 3 to distinguish this case from fatal error
conditions, which are reported using error code 1. In either case,
any currently running scripts (the top-level script, if any, and any
other scripts which it may have in invoked) will be terminated
immediately. If the top-level command string contained multiple SQL
commands, processing will stop with the current command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>PORT</varname></term>
<listitem>
<para>
The database server port to which you are currently connected.
This is set every time you connect to a database (including
program start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>PROMPT1</varname></term>
<term><varname>PROMPT2</varname></term>
<term><varname>PROMPT3</varname></term>
<listitem>
<para>
These specify what the prompts <application>psql</application>
issues should look like. See <xref
linkend="APP-PSQL-prompting"
endterm="APP-PSQL-prompting-title"> below.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>QUIET</varname></term>
<listitem>
<para>
Setting this variable to <literal>on</> is equivalent to the command
line option <option>-q</option>. It is probably not too useful in
interactive mode.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SINGLELINE</varname></term>
<listitem>
<para>
Setting this variable to <literal>on</> is equivalent to the command
line option <option>-S</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SINGLESTEP</varname></term>
<listitem>
<para>
Setting this variable to <literal>on</> is equivalent to the command
line option <option>-s</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>USER</varname></term>
<listitem>
<para>
The database user you are currently connected as. This is set
every time you connect to a database (including program
start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>VERBOSITY</varname></term>
<listitem>
<para>
This variable can be set to the values <literal>default</>,
<literal>verbose</>, or <literal>terse</> to control the verbosity
of error reports.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect3>
<refsect3 id="APP-PSQL-interpolation">
<title id="APP-PSQL-interpolation-title"><acronym>SQL</acronym> Interpolation</title>
<para>
A key feature of <application>psql</application>
variables is that you can substitute (<quote>interpolate</quote>)
them into regular <acronym>SQL</acronym> statements, as well as the
arguments of meta-commands. Furthermore,
<application>psql</application> provides facilities for
ensuring that variable values used as SQL literals and identifiers are
properly quoted. The syntax for interpolating a value without
any quoting is to prepend the variable name with a colon
(<literal>:</literal>). For example,
<programlisting>
testdb=&gt; <userinput>\set foo 'my_table'</userinput>
testdb=&gt; <userinput>SELECT * FROM :foo;</userinput>
</programlisting>
would query the table <literal>my_table</literal>. Note that this
may be unsafe: the value of the variable is copied literally, so it can
contain unbalanced quotes, or even backslash commands. You must make sure
that it makes sense where you put it.
</para>
<para>
When a value is to be used as an SQL literal or identifier, it is
safest to arrange for it to be quoted. To quote the value of
a variable as an SQL literal, write a colon followed by the variable
name in single quotes. To quote the value as an SQL identifier, write
a colon followed by the variable name in double quotes.
These constructs deal correctly with quotes and other special
characters embedded within the variable value.
The previous example would be more safely written this way:
<programlisting>
testdb=&gt; <userinput>\set foo 'my_table'</userinput>
testdb=&gt; <userinput>SELECT * FROM :"foo";</userinput>
</programlisting>
</para>
<para>
Variable interpolation will not be performed within quoted
<acronym>SQL</acronym> literals and identifiers. Therefore, a
construction such as <literal>':foo'</> doesn't work to produce a quoted
literal from a variable's value (and it would be unsafe if it did work,
since it wouldn't correctly handle quotes embedded in the value).
</para>
<para>
One example use of this mechanism is to
copy the contents of a file into a table column.
First load the file into a variable and then interpolate the variable's
value as a quoted string:
<programlisting>
testdb=&gt; <userinput>\set content `cat my_file.txt`</userinput>
testdb=&gt; <userinput>INSERT INTO my_table VALUES (:'content');</userinput>
</programlisting>
(Note that this still won't work if <filename>my_file.txt</filename> contains NUL bytes.
<application>psql</application> does not support embedded NUL bytes in variable values.)
</para>
<para>
Since colons can legally appear in SQL commands, an apparent attempt
at interpolation (that is, <literal>:name</literal>,
<literal>:'name'</literal>, or <literal>:"name"</literal>) is not
replaced unless the named variable is currently set. In any case, you
can escape a colon with a backslash to protect it from substitution.
</para>
<para>
The colon syntax for variables is standard <acronym>SQL</acronym> for
embedded query languages, such as <application>ECPG</application>.
The colon syntaxes for array slices and type casts are
<productname>PostgreSQL</productname> extensions, which can sometimes
conflict with the standard usage. The colon-quote syntax for escaping a
variable's value as an SQL literal or identifier is a
<application>psql</application> extension.
</para>
</refsect3>
<refsect3 id="APP-PSQL-prompting">
<title id="APP-PSQL-prompting-title">Prompting</title>
<para>
The prompts <application>psql</application> issues can be customized
to your preference. The three variables <varname>PROMPT1</varname>,
<varname>PROMPT2</varname>, and <varname>PROMPT3</varname> contain strings
and special escape sequences that describe the appearance of the
prompt. Prompt 1 is the normal prompt that is issued when
<application>psql</application> requests a new command. Prompt 2 is
issued when more input is expected during command entry, for example
because the command was not terminated with a semicolon or a quote
was not closed.
Prompt 3 is issued when you are running an <acronym>SQL</acronym>
<command>COPY FROM STDIN</command> command and you need to type in
a row value on the terminal.
</para>
<para>
The value of the selected prompt variable is printed literally,
except where a percent sign (<literal>%</literal>) is encountered.
Depending on the next character, certain other text is substituted
instead. Defined substitutions are:
<variablelist>
<varlistentry>
<term><literal>%M</literal></term>
<listitem>
<para>
The full host name (with domain name) of the database server,
or <literal>[local]</literal> if the connection is over a Unix
domain socket, or
<literal>[local:<replaceable>/dir/name</replaceable>]</literal>,
if the Unix domain socket is not at the compiled in default
location.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%m</literal></term>
<listitem>
<para>
The host name of the database server, truncated at the
first dot, or <literal>[local]</literal> if the connection is
over a Unix domain socket.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%&gt;</literal></term>
<listitem><para>The port number at which the database server is listening.</para></listitem>
</varlistentry>
<varlistentry>
<term><literal>%n</literal></term>
<listitem>
<para>
The database session user name. (The expansion of this
value might change during a database session as the result
of the command <command>SET SESSION
AUTHORIZATION</command>.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%/</literal></term>
<listitem><para>The name of the current database.</para></listitem>
</varlistentry>
<varlistentry>
<term><literal>%~</literal></term>
<listitem><para>Like <literal>%/</literal>, but the output is <literal>~</literal>
(tilde) if the database is your default database.</para></listitem>
</varlistentry>
<varlistentry>
<term><literal>%#</literal></term>
<listitem>
<para>
If the session user is a database superuser, then a
<literal>#</literal>, otherwise a <literal>&gt;</literal>.
(The expansion of this value might change during a database
session as the result of the command <command>SET SESSION
AUTHORIZATION</command>.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%R</literal></term>
<listitem>
<para>
In prompt 1 normally <literal>=</literal>,
but <literal>^</literal> if in single-line mode,
or <literal>!</literal> if the session is disconnected from the
database (which can happen if <command>\connect</command> fails).
In prompt 2 <literal>%R</literal> is replaced by a character that
depends on why <application>psql</application> expects more input:
<literal>-</literal> if the command simply wasn't terminated yet,
but <literal>*</literal> if there is an unfinished
<literal>/* ... */</literal> comment,
a single quote if there is an unfinished quoted string,
a double quote if there is an unfinished quoted identifier,
a dollar sign if there is an unfinished dollar-quoted string,
or <literal>(</literal> if there is an unmatched left parenthesis.
In prompt 3 <literal>%R</literal> doesn't produce anything.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%x</literal></term>
<listitem>
<para>
Transaction status: an empty string when not in a transaction
block, or <literal>*</> when in a transaction block, or
<literal>!</> when in a failed transaction block, or <literal>?</>
when the transaction state is indeterminate (for example, because
there is no connection).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%l</literal></term>
<listitem>
<para>
The line number inside the current statement, starting from <literal>1</>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%</literal><replaceable class="parameter">digits</replaceable></term>
<listitem>
<para>
The character with the indicated octal code is substituted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%:</literal><replaceable class="parameter">name</replaceable><literal>:</literal></term>
<listitem>
<para>
The value of the <application>psql</application> variable
<replaceable class="parameter">name</replaceable>. See the
section <xref linkend="APP-PSQL-variables"
endterm="APP-PSQL-variables-title"> for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%`</literal><replaceable class="parameter">command</replaceable><literal>`</literal></term>
<listitem>
<para>
The output of <replaceable
class="parameter">command</replaceable>, similar to ordinary
<quote>back-tick</quote> substitution.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%[</literal> ... <literal>%]</literal></term>
<listitem>
<para>
Prompts can contain terminal control characters which, for
example, change the color, background, or style of the prompt
text, or change the title of the terminal window. In order for
the line editing features of <application>Readline</application> to work properly, these
non-printing control characters must be designated as invisible
by surrounding them with <literal>%[</literal> and
<literal>%]</literal>. Multiple pairs of these can occur within
the prompt. For example:
<programlisting>
testdb=&gt; \set PROMPT1 '%[%033[1;33;40m%]%n@%/%R%[%033[0m%]%# '
</programlisting>
results in a boldfaced (<literal>1;</literal>) yellow-on-black
(<literal>33;40</literal>) prompt on VT100-compatible, color-capable
terminals.
</para>
</listitem>
</varlistentry>
</variablelist>
To insert a percent sign into your prompt, write
<literal>%%</literal>. The default prompts are
<literal>'%/%R%# '</literal> for prompts 1 and 2, and
<literal>'&gt;&gt; '</literal> for prompt 3.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>tcsh</application>.
</para>
</note>
</refsect3>
<refsect3>
<title>Command-Line Editing</title>
<para>
<application>psql</application> supports the <application>Readline</application>
library for convenient line editing and retrieval. The command
history is automatically saved when <application>psql</application>
exits and is reloaded when
<application>psql</application> starts up. Tab-completion is also
supported, although the completion logic makes no claim to be an
<acronym>SQL</acronym> parser. The queries generated by tab-completion
can also interfere with other SQL commands, e.g. <literal>SET
TRANSACTION ISOLATION LEVEL</>.
If for some reason you do not like the tab completion, you
can turn it off by putting this in a file named
<filename>.inputrc</filename> in your home directory:
<programlisting>
$if psql
set disable-completion on
$endif
</programlisting>
(This is not a <application>psql</application> but a
<application>Readline</application> feature. Read its documentation
for further details.)
</para>
</refsect3>
</refsect2>
</refsect1>
<refsect1 id="app-psql-environment">
<title id="app-psql-environment-title">Environment</title>
<variablelist>
<varlistentry>
<term><envar>COLUMNS</envar></term>
<listitem>
<para>
If <literal>\pset columns</> is zero, controls the
width for the <literal>wrapped</> format and width for determining
if wide output requires the pager or should be switched to the
vertical format in expanded auto mode.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>PAGER</envar></term>
<listitem>
<para>
If the query results do not fit on the screen, they are piped
through this command. Typical values are
<literal>more</literal> or <literal>less</literal>. The default
is platform-dependent. Use of the pager can be disabled by setting
<envar>PAGER</envar> to empty, or by using pager-related options of
the <command>\pset</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>PGDATABASE</envar></term>
<term><envar>PGHOST</envar></term>
<term><envar>PGPORT</envar></term>
<term><envar>PGUSER</envar></term>
<listitem>
<para>
Default connection parameters (see <xref linkend="libpq-envars">).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>PSQL_EDITOR</envar></term>
<term><envar>EDITOR</envar></term>
<term><envar>VISUAL</envar></term>
<listitem>
<para>
Editor used by the <command>\e</command> and
<command>\ef</command> commands. The variables are examined in
the order listed; the first that is set is used.
</para>
<para>
The built-in default editors are <filename>vi</filename> on Unix
systems and <filename>notepad.exe</filename> on Windows systems.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>PSQL_EDITOR_LINENUMBER_ARG</envar></term>
<listitem>
<para>
When <command>\e</command> or <command>\ef</command> is used
with a line number argument, this variable specifies the
command-line argument used to pass the starting line number to
the user's editor. For editors such as <productname>Emacs</> or
<productname>vi</>, this is a plus sign. Include a trailing
space in the value of the variable if there needs to be space
between the option name and the line number. Examples:
<programlisting>
PSQL_EDITOR_LINENUMBER_ARG='+'
PSQL_EDITOR_LINENUMBER_ARG='--line '
</programlisting>
</para>
<para>
The default is <literal>+</literal> on Unix systems
(corresponding to the default editor <filename>vi</filename>,
and useful for many other common editors); but there is no
default on Windows systems.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>PSQL_HISTORY</envar></term>
<listitem>
<para>
Alternative location for the command history file. Tilde (<literal>~</literal>) expansion is performed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>PSQLRC</envar></term>
<listitem>
<para>
Alternative location of the user's <filename>.psqlrc</filename> file. Tilde (<literal>~</literal>) expansion is performed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>SHELL</envar></term>
<listitem>
<para>
Command executed by the <command>\!</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><envar>TMPDIR</envar></term>
<listitem>
<para>
Directory for storing temporary files. The default is
<filename>/tmp</filename>.
</para>
</listitem>
</varlistentry>
</variablelist>
<para>
This utility, like most other <productname>PostgreSQL</> utilities,
also uses the environment variables supported by <application>libpq</>
(see <xref linkend="libpq-envars">).
</para>
</refsect1>
<refsect1>
<title>Files</title>
<variablelist>
<varlistentry>
<term><filename>psqlrc</filename> and <filename>~/.psqlrc</filename></term>
<listitem>
<para>
Unless it is passed an <option>-X</option> or <option>-c</option> option,
<application>psql</application> attempts to read and execute commands
from the system-wide startup file (<filename>psqlrc</filename>) and then
the user's personal startup file (<filename>~/.psqlrc</filename>), after
connecting to the database but before accepting normal commands.
These files can be used to set up the client and/or the server to taste,
typically with <command>\set</command> and <command>SET</command>
commands.
</para>
<para>
The system-wide startup file is named <filename>psqlrc</filename> and is
sought in the installation's <quote>system configuration</> directory,
which is most reliably identified by running <literal>pg_config
--sysconfdir</>. By default this directory will be <filename>../etc/</>
relative to the directory containing
the <productname>PostgreSQL</productname> executables. The name of this
directory can be set explicitly via the <envar>PGSYSCONFDIR</envar>
environment variable.
</para>
<para>
The user's personal startup file is named <filename>.psqlrc</filename>
and is sought in the invoking user's home directory. On Windows, which
lacks such a concept, the personal startup file is named
<filename>%APPDATA%\postgresql\psqlrc.conf</filename>.
The location of the user's startup file can be set explicitly via
the <envar>PSQLRC</envar> environment variable.
</para>
<para>
Both the system-wide startup file and the user's personal startup file
can be made <application>psql</application>-version-specific
by appending a dash and the <productname>PostgreSQL</productname>
major or minor release number to the file name,
for example <filename>~/.psqlrc-9.2</filename> or
<filename>~/.psqlrc-9.2.5</filename>. The most specific
version-matching file will be read in preference to a
non-version-specific file.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><filename>.psql_history</filename></term>
<listitem>
<para>
The command-line history is stored in the file
<filename>~/.psql_history</filename>, or
<filename>%APPDATA%\postgresql\psql_history</filename> on Windows.
</para>
<para>
The location of the history file can be set explicitly via
the <envar>PSQL_HISTORY</envar> environment variable.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<itemizedlist>
<listitem>
<para>
In an earlier life <application>psql</application> allowed the
first argument of a single-letter backslash command to start
directly after the command, without intervening whitespace.
As of <productname>PostgreSQL</productname> 8.4 this is no
longer allowed.
</para>
</listitem>
<listitem>
<para><application>psql</application> works best with servers of the same
or an older major version. Backslash commands are particularly likely
to fail if the server is of a newer version than <application>psql</>
itself. However, backslash commands of the <literal>\d</> family should
work with servers of versions back to 7.4, though not necessarily with
servers newer than <application>psql</> itself. The general
functionality of running SQL commands and displaying query results
should also work with servers of a newer major version, but this cannot
be guaranteed in all cases.
</para>
<para>
If you want to use <application>psql</application> to connect to several
servers of different major versions, it is recommended that you use the
newest version of <application>psql</application>. Alternatively, you
can keep a copy of <application>psql</application> from each major
version around and be sure to use the version that matches the
respective server. But in practice, this additional complication should
not be necessary.
</para>
</listitem>
</itemizedlist>
</refsect1>
<refsect1>
<title>Notes for Windows Users</title>
<para>
<application>psql</application> is built as a <quote>console
application</>. Since the Windows console windows use a different
encoding than the rest of the system, you must take special care
when using 8-bit characters within <application>psql</application>.
If <application>psql</application> detects a problematic
console code page, it will warn you at startup. To change the
console code page, two things are necessary:
<itemizedlist>
<listitem>
<para>
Set the code page by entering <userinput>cmd.exe /c chcp
1252</userinput>. (1252 is a code page that is appropriate for
German; replace it with your value.) If you are using Cygwin,
you can put this command in <filename>/etc/profile</filename>.
</para>
</listitem>
<listitem>
<para>
Set the console font to <literal>Lucida Console</>, because the
raster font does not work with the ANSI code page.
</para>
</listitem>
</itemizedlist></para>
</refsect1>
<refsect1 id="APP-PSQL-examples">
<title id="APP-PSQL-examples-title">Examples</title>
<para>
The first example shows how to spread a command over several lines of
input. Notice the changing prompt:
<programlisting>
testdb=&gt; <userinput>CREATE TABLE my_table (</userinput>
testdb(&gt; <userinput> first integer not null default 0,</userinput>
testdb(&gt; <userinput> second text)</userinput>
testdb-&gt; <userinput>;</userinput>
CREATE TABLE
</programlisting>
Now look at the table definition again:
<programlisting>
testdb=&gt; <userinput>\d my_table</userinput>
Table "my_table"
Attribute | Type | Modifier
-----------+---------+--------------------
first | integer | not null default 0
second | text |
</programlisting>
Now we change the prompt to something more interesting:
<programlisting>
testdb=&gt; <userinput>\set PROMPT1 '%n@%m %~%R%# '</userinput>
peter@localhost testdb=&gt;
</programlisting>
Let's assume you have filled the table with data and want to take a
look at it:
<programlisting>
peter@localhost testdb=&gt; SELECT * FROM my_table;
first | second
-------+--------
1 | one
2 | two
3 | three
4 | four
(4 rows)
</programlisting>
You can display tables in different ways by using the
<command>\pset</command> command:
<programlisting>
peter@localhost testdb=&gt; <userinput>\pset border 2</userinput>
Border style is 2.
peter@localhost testdb=&gt; <userinput>SELECT * FROM my_table;</userinput>
+-------+--------+
| first | second |
+-------+--------+
| 1 | one |
| 2 | two |
| 3 | three |
| 4 | four |
+-------+--------+
(4 rows)
peter@localhost testdb=&gt; <userinput>\pset border 0</userinput>
Border style is 0.
peter@localhost testdb=&gt; <userinput>SELECT * FROM my_table;</userinput>
first second
----- ------
1 one
2 two
3 three
4 four
(4 rows)
peter@localhost testdb=&gt; <userinput>\pset border 1</userinput>
Border style is 1.
peter@localhost testdb=&gt; <userinput>\pset format unaligned</userinput>
Output format is unaligned.
peter@localhost testdb=&gt; <userinput>\pset fieldsep ","</userinput>
Field separator is ",".
peter@localhost testdb=&gt; <userinput>\pset tuples_only</userinput>
Showing only tuples.
peter@localhost testdb=&gt; <userinput>SELECT second, first FROM my_table;</userinput>
one,1
two,2
three,3
four,4
</programlisting>
Alternatively, use the short commands:
<programlisting>
peter@localhost testdb=&gt; <userinput>\a \t \x</userinput>
Output format is aligned.
Tuples only is off.
Expanded display is on.
peter@localhost testdb=&gt; <userinput>SELECT * FROM my_table;</userinput>
-[ RECORD 1 ]-
first | 1
second | one
-[ RECORD 2 ]-
first | 2
second | two
-[ RECORD 3 ]-
first | 3
second | three
-[ RECORD 4 ]-
first | 4
second | four
</programlisting></para>
</refsect1>
</refentry>
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