database/postgres
database/postgres
1
0
Fork 0
mirror of https://github.com/postgres/postgres.git synced 2025-04-29 13:56:47 +03:00
Code
postgres/doc/src/sgml/ref/psql-ref.sgml
Peter Eisentraut 197d33ccbe Fix some trailing whitespace in documentation files
2021-04-22 22:47:57 +02:00

5051 lines
204 KiB
Plaintext
Raw Blame History

<!--
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 or from command line
arguments. In addition, <application>psql</application> 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</option></term>
<term><option>--echo-all</option></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</option></term>
<term><option>--no-align</option></term>
<listitem>
<para>
Switches to unaligned output mode. (The default output mode is
<literal>aligned</literal>.) This is equivalent to
<command>\pset format unaligned</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-b</option></term>
<term><option>--echo-errors</option></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></option></term>
<term><option>--command=<replaceable class="parameter">command</replaceable></option></term>
<listitem>
<para>
Specifies that <application>psql</application> is to execute the given
command string, <replaceable class="parameter">command</replaceable>.
This option can be repeated and combined in any order with
the <option>-f</option> option. When either <option>-c</option>
or <option>-f</option> is specified, <application>psql</application>
does not read commands from standard input; instead it terminates
after processing all the <option>-c</option> and <option>-f</option>
options in sequence.
</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 within a <option>-c</option> option. To achieve that,
you could use repeated <option>-c</option> options or pipe the string
into <application>psql</application>, for example:
<programlisting>
psql -c '\x' -c 'SELECT * FROM foo;'
</programlisting>
or
<programlisting>
echo '\x \\ SELECT * FROM foo;' | psql
</programlisting>
(<literal>\\</literal> is the separator meta-command.)
</para>
<para>
Each <acronym>SQL</acronym> command string passed
to <option>-c</option> is sent to the server as a single request.
Because of this, the server executes it as a single transaction even
if the string contains multiple <acronym>SQL</acronym> commands,
unless there are explicit <command>BEGIN</command>/<command>COMMIT</command>
commands included in the string to divide it into multiple
transactions. (See <xref linkend="protocol-flow-multi-statement"/>
for more details about how the server handles multi-query strings.)
Also, <application>psql</application> only prints the
result of the last <acronym>SQL</acronym> command in the string.
This is different from the behavior when the same string is read from
a file or fed to <application>psql</application>'s standard input,
because then <application>psql</application> sends
each <acronym>SQL</acronym> command separately.
</para>
<para>
Because of this behavior, putting more than one SQL command in a
single <option>-c</option> string often has unexpected results.
It's better to use repeated <option>-c</option> commands or 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>--csv</option></term>
<listitem>
<para>
Switches to <acronym>CSV</acronym> (Comma-Separated Values) output
mode. This is equivalent to <command>\pset format csv</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-d <replaceable class="parameter">dbname</replaceable></option></term>
<term><option>--dbname=<replaceable class="parameter">dbname</replaceable></option></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. The <replaceable>dbname</replaceable>
can be a <link linkend="libpq-connstring">connection string</link>.
If so, connection string parameters will override any conflicting
command line options.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-e</option></term>
<term><option>--echo-queries</option></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</option></term>
<term><option>--echo-hidden</option></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</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-f <replaceable class="parameter">filename</replaceable></option></term>
<term><option>--file=<replaceable class="parameter">filename</replaceable></option></term>
<listitem>
<para>
Read commands from the
file <replaceable class="parameter">filename</replaceable>,
rather than standard input.
This option can be repeated and combined in any order with
the <option>-c</option> option. When either <option>-c</option>
or <option>-f</option> is specified, <application>psql</application>
does not read commands from standard input; instead it terminates
after processing all the <option>-c</option> and <option>-f</option>
options in sequence.
Except for that, this option is largely 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</command> meta-command. This can be used to intersperse
interactive input with input from files. 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></option></term>
<term><option>--field-separator=<replaceable class="parameter">separator</replaceable></option></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></option></term>
<term><option>--host=<replaceable class="parameter">hostname</replaceable></option></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</option></term>
<term><option>--html</option></term>
<listitem>
<para>
Switches to <acronym>HTML</acronym> output mode. This is
equivalent to <command>\pset format html</command> or the
<command>\H</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-l</option></term>
<term><option>--list</option></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>
<para>
When this option is used, <application>psql</application> will connect
to the database <literal>postgres</literal>, unless a different database
is named on the command line (option <option>-d</option> or non-option
argument, possibly via a service entry, but not via an environment
variable).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-L <replaceable class="parameter">filename</replaceable></option></term>
<term><option>--log-file=<replaceable class="parameter">filename</replaceable></option></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</option></term>
<term><option>--no-readline</option></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></option></term>
<term><option>--output=<replaceable class="parameter">filename</replaceable></option></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></option></term>
<term><option>--port=<replaceable class="parameter">port</replaceable></option></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></option></term>
<term><option>--pset=<replaceable class="parameter">assignment</replaceable></option></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</option></term>
<term><option>--quiet</option></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</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-R <replaceable class="parameter">separator</replaceable></option></term>
<term><option>--record-separator=<replaceable class="parameter">separator</replaceable></option></term>
<listitem>
<para>
Use <replaceable class="parameter">separator</replaceable> as the
record separator for unaligned output. This is equivalent to
<command>\pset recordsep</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-s</option></term>
<term><option>--single-step</option></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</option></term>
<term><option>--single-line</option></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</option></term>
<term><option>--tuples-only</option></term>
<listitem>
<para>
Turn off printing of column names and result row count footers,
etc. This is equivalent to <command>\t</command> or
<command>\pset tuples_only</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-T <replaceable class="parameter">table_options</replaceable></option></term>
<term><option>--table-attr=<replaceable class="parameter">table_options</replaceable></option></term>
<listitem>
<para>
Specifies options to be placed within the
<acronym>HTML</acronym> <sgmltag>table</sgmltag> tag. See
<command>\pset tableattr</command> for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-U <replaceable class="parameter">username</replaceable></option></term>
<term><option>--username=<replaceable class="parameter">username</replaceable></option></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></option></term>
<term><option>--set=<replaceable class="parameter">assignment</replaceable></option></term>
<term><option>--variable=<replaceable class="parameter">assignment</replaceable></option></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 command line processing, so variables that reflect
connection state will get overwritten later.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-V</option></term>
<term><option>--version</option></term>
<listitem>
<para>
Print the <application>psql</application> version and exit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-w</option></term>
<term><option>--no-password</option></term>
<listitem>
<para>
Never issue a password prompt. If the server requires password
authentication and a password is not available from other sources
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</option></term>
<term><option>--password</option></term>
<listitem>
<para>
Force <application>psql</application> to prompt for a
password before connecting to a database, even if the password will
not be used.
</para>
<para>
If the server requires password authentication and a password is not
available from other sources such as a <filename>.pgpass</filename>
file, <application>psql</application> will prompt for a
password in any case. 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</option> 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</option></term>
<term><option>--expanded</option></term>
<listitem>
<para>
Turn on the expanded table formatting mode. This is equivalent to
<command>\x</command> or <command>\pset expanded</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-X,</option></term>
<term><option>--no-psqlrc</option></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. This is
equivalent to <command>\pset fieldsep_zero</command>.
</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>.
This is equivalent to <command>\pset recordsep_zero</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-1</option></term>
<term><option>--single-transaction</option></term>
<listitem>
<para>
This option can only be used in combination with one or more
<option>-c</option> and/or <option>-f</option> options. It causes
<application>psql</application> to issue a <command>BEGIN</command> command
before the first such option and a <command>COMMIT</command> command after
the last one, thereby wrapping all the commands into a single
transaction. This ensures that either all the commands complete
successfully, or no changes are applied.
</para>
<para>
If the commands themselves
contain <command>BEGIN</command>, <command>COMMIT</command>,
or <command>ROLLBACK</command>, this option will not have the desired
effects. Also, if an individual command cannot be executed inside a
transaction block, specifying this option will cause the whole
transaction to fail.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-?</option></term>
<term><option>--help[=<replaceable class="parameter">topic</replaceable>]</option></term>
<listitem>
<para>
Show help about <application>psql</application> and exit. The optional
<replaceable class="parameter">topic</replaceable> parameter (defaulting
to <literal>options</literal>) selects which part of <application>psql</application> is
explained: <literal>commands</literal> describes <application>psql</application>'s
backslash commands; <literal>options</literal> describes the command-line
options that can be passed to <application>psql</application>;
and <literal>variables</literal> 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</application> will connect via a Unix-domain socket
to a server on the local host, or via TCP/IP to <literal>localhost</literal> 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</filename> 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
<link linkend="sql-listen"><command>LISTEN</command></link> and
<link linkend="sql-notify"><command>NOTIFY</command></link>.
</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>
If an unquoted colon (<literal>:</literal>) followed by a
<application>psql</application> variable name appears within an argument, it is
replaced by the variable's value, as described in <xref
linkend="app-psql-interpolation"/> below.
The forms <literal>:'<replaceable>variable_name</replaceable>'</literal> and
<literal>:"<replaceable>variable_name</replaceable>"</literal> described there
work as well.
The <literal>:{?<replaceable>variable_name</replaceable>}</literal> syntax allows
testing whether a variable is defined. It is substituted by
TRUE or FALSE.
Escaping the colon with a backslash protects it from substitution.
</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. Within the text enclosed in backquotes,
no special quoting or other processing occurs, except that appearances
of <literal>:<replaceable>variable_name</replaceable></literal> where
<replaceable>variable_name</replaceable> is a <application>psql</application> variable name
are replaced by the variable's value. Also, appearances of
<literal>:'<replaceable>variable_name</replaceable>'</literal> are replaced by the
variable's value suitably quoted to become a single shell command
argument. (The latter form is almost always preferable, unless you are
very sure of what is in the variable.) Because carriage return and line
feed characters cannot be safely quoted on all platforms, the
<literal>:'<replaceable>variable_name</replaceable>'</literal> form prints an
error message and does not substitute the variable value when such
characters appear in the value.
</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>"</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</literal> is interpreted as <literal>fooBARbaz</literal>,
and <literal>"A weird"" name"</literal> becomes <literal>A weird"
name</literal>.
</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>
Many of the meta-commands act on the <firstterm>current query buffer</firstterm>.
This is simply a buffer holding whatever SQL command text has been typed
but not yet sent to the server for execution. This will include previous
input lines as well as any text appearing before the meta-command on the
same 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</productname>
server. The connection parameters to use can be specified either
using a positional syntax (one or more of database name, user,
host, and port), or using a <replaceable>conninfo</replaceable>
connection string as detailed in
<xref linkend="libpq-connstring"/>. If no arguments are given, a
new connection is made using the same parameters as before.
</para>
<para>
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>
The new connection can re-use connection parameters from the previous
connection; not only database name, user, host, and port, but other
settings such as <replaceable>sslmode</replaceable>. By default,
parameters are re-used in the positional syntax, but not when
a <replaceable>conninfo</replaceable> string is given. Passing a
first argument of <literal>-reuse-previous=on</literal>
or <literal>-reuse-previous=off</literal> overrides that default. If
parameters are re-used, then any parameter not explicitly specified as
a positional parameter or in the <replaceable>conninfo</replaceable>
string is taken from the existing connection's parameters. An
exception is that if the <replaceable>host</replaceable> setting
is changed from its previous value using the positional syntax,
any <replaceable>hostaddr</replaceable> setting present in the
existing connection's parameters is dropped.
Also, any password used for the existing connection will be re-used
only if the user, host, and port settings are not changed.
When the command neither specifies nor reuses a particular parameter,
the <application>libpq</application> default is used.
</para>
<para>
If the new connection is successfully made, the previous
connection is closed.
If the connection attempt fails (wrong user name, access
denied, etc.), the previous connection will be kept if
<application>psql</application> is in interactive mode. But when
executing a non-interactive script, the old connection is closed
and an error is reported. That may or may not terminate the
script; if it does not, all database-accessing commands will fail
until another <literal>\connect</literal> command is successfully
executed. 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.
Note that whenever a <literal>\connect</literal> command attempts
to re-use parameters, the values re-used are those of the last
successful connection, not of any failed attempts made subsequently.
However, in the case of a
non-interactive <literal>\connect</literal> failure, no parameters
are allowed to be re-used later, since the script would likely be
expecting the values from the failed <literal>\connect</literal>
to be re-used.
</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 -reuse-previous=on sslmode=require -- changes only sslmode
=&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> ) ] }
<literal>from</literal>
{ <replaceable class="parameter">'filename'</replaceable> | program <replaceable class="parameter">'command'</replaceable> | stdin | pstdin }
[ [ with ] ( <replaceable class="parameter">option</replaceable> [, ...] ) ]
[ where <replaceable class="parameter">condition</replaceable> ]</literal></term>
<term><literal>\copy { <replaceable class="parameter">table</replaceable> [ ( <replaceable class="parameter">column_list</replaceable> ) ] | ( <replaceable class="parameter">query</replaceable> ) }
<literal>to</literal>
{ <replaceable class="parameter">'filename'</replaceable> | program <replaceable class="parameter">'command'</replaceable> | stdout | 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> <link linkend="sql-copy"><command>COPY</command></link>
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</literal> 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</literal>, data rows are read from the same
source that issued the command, continuing until <literal>\.</literal>
is read or the stream reaches <acronym>EOF</acronym>. This option is useful
for populating tables in-line within a SQL script file.
For <literal>\copy ... to stdout</literal>, output is sent to the same place
as <application>psql</application> command output, and
the <literal>COPY <replaceable>count</replaceable></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</literal>
option, write <literal>from pstdin</literal> or <literal>to pstdout</literal>.
</para>
<para>
The syntax of this command is similar to that of the
<acronym>SQL</acronym> <link linkend="sql-copy"><command>COPY</command></link>
command. All options other than the data source/destination are
as specified for <command>COPY</command>.
Because of this, special parsing rules apply to the <command>\copy</command>
meta-command. Unlike most other meta-commands, the entire remainder
of the line is always taken to be the arguments of <command>\copy</command>,
and neither variable interpolation nor backquote expansion are
performed in the arguments.
</para>
<tip>
<para>
Another way to obtain the same result as <literal>\copy
... to</literal> is to use the <acronym>SQL</acronym> <literal>COPY
... TO STDOUT</literal> command and terminate it
with <literal>\g <replaceable>filename</replaceable></literal>
or <literal>\g |<replaceable>program</replaceable></literal>.
Unlike <literal>\copy</literal>, this method allows the command to
span multiple lines; also, variable interpolation and backquote
expansion can be used.
</para>
</tip>
<tip>
<para>
These operations are not as efficient as the <acronym>SQL</acronym>
<command>COPY</command> command with a file or program data source or
destination, 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 id="app-psql-meta-commands-crosstabview">
<term><literal>\crosstabview [
<replaceable class="parameter">colV</replaceable>
[ <replaceable class="parameter">colH</replaceable>
[ <replaceable class="parameter">colD</replaceable>
[ <replaceable class="parameter">sortcolH</replaceable>
] ] ] ] </literal></term>
<listitem>
<para>
Executes the current query buffer (like <literal>\g</literal>) and
shows the results in a crosstab grid.
The query must return at least three columns.
The output column identified by <replaceable class="parameter">colV</replaceable>
becomes a vertical header and the output column identified by
<replaceable class="parameter">colH</replaceable>
becomes a horizontal header.
<replaceable class="parameter">colD</replaceable> identifies
the output column to display within the grid.
<replaceable class="parameter">sortcolH</replaceable> identifies
an optional sort column for the horizontal header.
</para>
<para>
Each column specification can be a column number (starting at 1) or
a column name. The usual SQL case folding and quoting rules apply to
column names. If omitted,
<replaceable class="parameter">colV</replaceable> is taken as column 1
and <replaceable class="parameter">colH</replaceable> as column 2.
<replaceable class="parameter">colH</replaceable> must differ from
<replaceable class="parameter">colV</replaceable>.
If <replaceable class="parameter">colD</replaceable> is not
specified, then there must be exactly three columns in the query
result, and the column that is neither
<replaceable class="parameter">colV</replaceable> nor
<replaceable class="parameter">colH</replaceable>
is taken to be <replaceable class="parameter">colD</replaceable>.
</para>
<para>
The vertical header, displayed as the leftmost column, contains the
values found in column <replaceable class="parameter">colV</replaceable>, in the
same order as in the query results, but with duplicates removed.
</para>
<para>
The horizontal header, displayed as the first row, contains the values
found in column <replaceable class="parameter">colH</replaceable>,
with duplicates removed. By default, these appear in the same order
as in the query results. But if the
optional <replaceable class="parameter">sortcolH</replaceable> argument is given,
it identifies a column whose values must be integer numbers, and the
values from <replaceable class="parameter">colH</replaceable> will
appear in the horizontal header sorted according to the
corresponding <replaceable class="parameter">sortcolH</replaceable> values.
</para>
<para>
Inside the crosstab grid, for each distinct value <literal>x</literal>
of <replaceable class="parameter">colH</replaceable> and each distinct
value <literal>y</literal>
of <replaceable class="parameter">colV</replaceable>, the cell located
at the intersection <literal>(x,y)</literal> contains the value of
the <literal>colD</literal> column in the query result row for which
the value of <replaceable class="parameter">colH</replaceable>
is <literal>x</literal> and the value
of <replaceable class="parameter">colV</replaceable>
is <literal>y</literal>. If there is no such row, the cell is empty. If
there are multiple such rows, an error is reported.
</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</quote> is defined in
<xref linkend="app-psql-patterns"/> below.)
</para>
<para>
For some types of relation, <literal>\d</literal> 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-altertable-replica-identity">replica
identity</link> setting and the
<link linkend="sql-create-access-method">access method</link> name
if the relation has an access method.
</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>\dA[+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists access methods. If <replaceable
class="parameter">pattern</replaceable> is specified, only access
methods whose names match the pattern are shown. If
<literal>+</literal> is appended to the command name, each access
method is listed with its associated handler function and description.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>\dAc[+]
[<link linkend="app-psql-patterns"><replaceable class="parameter">access-method-pattern</replaceable></link>
[<link linkend="app-psql-patterns"><replaceable class="parameter">input-type-pattern</replaceable></link>]]
</literal>
</term>
<listitem>
<para>
Lists operator classes
(see <xref linkend="xindex-opclass"/>).
If <replaceable class="parameter">access-method-pattern</replaceable>
is specified, only operator classes associated with access methods whose
names match that pattern are listed.
If <replaceable class="parameter">input-type-pattern</replaceable>
is specified, only operator classes associated with input types whose
names match that pattern are listed.
If <literal>+</literal> is appended to the command name, each operator
class is listed with its associated operator family and owner.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>\dAf[+]
[<link linkend="app-psql-patterns"><replaceable class="parameter">access-method-pattern</replaceable></link>
[<link linkend="app-psql-patterns"><replaceable class="parameter">input-type-pattern</replaceable></link>]]
</literal>
</term>
<listitem>
<para>
Lists operator families
(see <xref linkend="xindex-opfamily"/>).
If <replaceable class="parameter">access-method-pattern</replaceable>
is specified, only operator families associated with access methods whose
names match that pattern are listed.
If <replaceable class="parameter">input-type-pattern</replaceable>
is specified, only operator families associated with input types whose
names match that pattern are listed.
If <literal>+</literal> is appended to the command name, each operator
family is listed with its owner.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>\dAo[+]
[<link linkend="app-psql-patterns"><replaceable class="parameter">access-method-pattern</replaceable></link>
[<link linkend="app-psql-patterns"><replaceable class="parameter">operator-family-pattern</replaceable></link>]]
</literal>
</term>
<listitem>
<para>
Lists operators associated with operator families
(see <xref linkend="xindex-strategies"/>).
If <replaceable class="parameter">access-method-pattern</replaceable>
is specified, only members of operator families associated with access
methods whose names match that pattern are listed.
If <replaceable class="parameter">operator-family-pattern</replaceable>
is specified, only members of operator families whose names match that
pattern are listed.
If <literal>+</literal> is appended to the command name, each operator
is listed with its sort operator family (if it is an ordering operator).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>
<literal>\dAp[+]
[<link linkend="app-psql-patterns"><replaceable class="parameter">access-method-pattern</replaceable></link>
[<link linkend="app-psql-patterns"><replaceable class="parameter">operator-family-pattern</replaceable></link>]]
</literal>
</term>
<listitem>
<para>
Lists support functions associated with operator families
(see <xref linkend="xindex-support"/>).
If <replaceable class="parameter">access-method-pattern</replaceable>
is specified, only functions of operator families associated with
access methods whose names match that pattern are listed.
If <replaceable class="parameter">operator-family-pattern</replaceable>
is specified, only functions of operator families whose names match
that pattern are listed.
If <literal>+</literal> is appended to the command name, functions are
displayed verbosely, with their actual parameter lists.
</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>,
<literal>operator class</literal>, <literal>operator family</literal>,
<literal>rule</literal>, and <literal>trigger</literal>. 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 <link
linkend="sql-comment"><command>COMMENT</command></link>
<acronym>SQL</acronym> command.
</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>\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 <link linkend="sql-alterdefaultprivileges"><command>ALTER DEFAULT
PRIVILEGES</command></link> command is used to set default access
privileges. The meaning of the privilege display is explained in
<xref linkend="ddl-priv"/>.
</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>\dti</literal> lists
tables and indexes. If <literal>+</literal> is
appended to the command name, each object is listed with its
persistence status (permanent, temporary, or unlogged),
physical size on disk, and 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 access privileges, 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 access privileges, options, and description of the
foreign-data wrapper are also shown.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\df[anptwS+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> [ <replaceable class="parameter">arg_pattern</replaceable> ... ] ]</literal></term>
<listitem>
<para>
Lists functions, together with their result data types, argument data
types, and function types, which are classified as <quote>agg</quote>
(aggregate), <quote>normal</quote>, <quote>procedure</quote>, <quote>trigger</quote>, or <quote>window</quote>.
To display only functions
of specific type(s), add the corresponding letters <literal>a</literal>,
<literal>n</literal>, <literal>p</literal>, <literal>t</literal>, or <literal>w</literal> to the command.
If <replaceable
class="parameter">pattern</replaceable> is specified, only
functions whose names match the pattern are shown.
Any additional arguments are type-name patterns, which are matched
to the type names of the first, second, and so on arguments of the
function. (Matching functions can have more arguments than what
you specify. To prevent that, write a dash <literal>-</literal> as
the last <replaceable class="parameter">arg_pattern</replaceable>.)
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 volatility,
parallel safety, owner, security classification, access privileges,
language, source code and description.
</para>
</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[S+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists database roles.
(Since the concepts of <quote>users</quote> and <quote>groups</quote> have been
unified into <quote>roles</quote>, this command is now equivalent to
<literal>\du</literal>.)
By default, only user-created roles are shown; supply the
<literal>S</literal> modifier to include system roles.
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> [ <replaceable class="parameter">arg_pattern</replaceable> [ <replaceable class="parameter">arg_pattern</replaceable> ] ] ]</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.
If one <replaceable class="parameter">arg_pattern</replaceable> is
specified, only prefix operators whose right argument's type name
matches that pattern are listed.
If two <replaceable class="parameter">arg_pattern</replaceable>s
are specified, only binary operators whose argument type names match
those patterns are listed. (Alternatively, write <literal>-</literal>
for the unused argument of a unary operator.)
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 <link linkend="sql-grant"><command>GRANT</command></link> and
<link linkend="sql-revoke"><command>REVOKE</command></link>
commands are used to set access privileges. The meaning of the
privilege display is explained in
<xref linkend="ddl-priv"/>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dP[itn+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists partitioned relations.
If <replaceable class="parameter">pattern</replaceable>
is specified, only entries whose name matches the pattern are listed.
The modifiers <literal>t</literal> (tables) and <literal>i</literal>
(indexes) can be appended to the command, filtering the kind of
relations to list. By default, partitioned tables and indexes are
listed.
</para>
<para>
If the modifier <literal>n</literal> (<quote>nested</quote>) is used,
or a pattern is specified, then non-root partitioned relations are
included, and a column is shown displaying the parent of each
partitioned relation.
</para>
<para>
If <literal>+</literal> is appended to the command name, the sum of the
sizes of each relation's partitions is also displayed, along with the
relation's description.
If <literal>n</literal> is combined with <literal>+</literal>, two
sizes are shown: one including the total size of directly-attached
leaf partitions, and another showing the total size of all partitions,
including indirectly attached sub-partitions.
</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>*</literal> is specified, all settings are listed, including those
not role-specific or database-specific, respectively.
</para>
<para>
The <link linkend="sql-alterrole"><command>ALTER ROLE</command></link> and
<link linkend="sql-alterdatabase"><command>ALTER DATABASE</command></link>
commands are used to define per-role and per-database configuration
settings.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dRp[+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists replication publications.
If <replaceable class="parameter">pattern</replaceable> is
specified, only those publications whose names match the pattern are
listed.
If <literal>+</literal> is appended to the command name, the tables
associated with each publication are shown as well.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dRs[+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists replication subscriptions.
If <replaceable class="parameter">pattern</replaceable> is
specified, only those subscriptions whose names match the pattern are
listed.
If <literal>+</literal> is appended to the command name, additional
properties of the subscriptions are shown.
</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> 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[S+] [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists database roles.
(Since the concepts of <quote>users</quote> and <quote>groups</quote> have been
unified into <quote>roles</quote>, this command is now equivalent to
<literal>\dg</literal>.)
By default, only user-created roles are shown; supply the
<literal>S</literal> modifier to include system roles.
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>\dX [ <link linkend="app-psql-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists extended statistics.
If <replaceable class="parameter">pattern</replaceable>
is specified, only those extended statistics whose names match the
pattern are listed.
</para>
<para>
The status of each kind of extended statistics is shown in a column
named after its statistic kind (e.g. Ndistinct).
"defined" means that it was requested when creating the statistics,
and NULL means it wasn't requested.
You can use pg_stats_ext if you'd like to know whether <link linkend="sql-analyze">
<command>ANALYZE</command></link> was run and statistics are available to the
planner.
</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> <literal> <optional> <replaceable class="parameter">filename</replaceable> </optional> <optional> <replaceable class="parameter">line_number</replaceable> </optional> </literal></term>
<listitem>
<para>
If <replaceable class="parameter">filename</replaceable> is
specified, the file is edited; after the editor exits, the file's
content is copied into the current 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. Or, if the current query buffer is empty, the most recently
executed query is copied to a temporary file and edited in the same
fashion.
</para>
<para>
If you edit a file or the previous query, and you quit the editor without
modifying the file, the query buffer is cleared.
Otherwise, the new contents of the query buffer are re-parsed according to
the normal rules of <application>psql</application>, treating the
whole buffer as a single line. Any complete queries are immediately
executed; that is, if the query buffer contains or ends with a
semicolon, everything up to that point is executed and removed from
the query buffer. Whatever remains in the query buffer is
redisplayed. Type semicolon or <literal>\g</literal> to send it,
or <literal>\r</literal> to cancel it by clearing the query buffer.
</para>
<para>
Treating the buffer as a single line primarily affects meta-commands:
whatever is in the buffer after a meta-command will be taken as
argument(s) to the meta-command, even if it spans multiple lines.
(Thus you cannot make meta-command-using scripts this way.
Use <command>\i</command> for that.)
</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 <xref linkend="app-psql-environment"/>, below, 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 evaluated arguments to standard output, separated by
spaces 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 (nor is the first argument).
</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. See also <command>\warn</command>.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ef <optional> <replaceable class="parameter">function_description</replaceable> <optional> <replaceable class="parameter">line_number</replaceable> </optional> </optional> </literal></term>
<listitem>
<para>
This command fetches and edits the definition of the named function or procedure,
in the form of a <command>CREATE OR REPLACE FUNCTION</command> or
<command>CREATE OR REPLACE PROCEDURE</command> command.
Editing is done in the same way as for <literal>\edit</literal>.
If you quit the editor without saving, the statement is discarded.
If you save and exit the editor, the updated command is executed immediately
if you added a semicolon to it. Otherwise it is redisplayed;
type semicolon or <literal>\g</literal> to send it, or <literal>\r</literal>
to cancel.
</para>
<para>
The target function can be specified by name alone, or by name
and arguments, for example <literal>foo(integer, text)</literal>.
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</command>
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>
<para>
Unlike most other meta-commands, the entire remainder of the line is
always taken to be the argument(s) of <command>\ef</command>, and neither
variable interpolation nor backquote expansion are performed in the
arguments.
</para>
<tip>
<para>
See <xref linkend="app-psql-environment"/>, below, 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>\errverbose</literal></term>
<listitem>
<para>
Repeats the most recent server error message at maximum
verbosity, as though <varname>VERBOSITY</varname> were set
to <literal>verbose</literal> and <varname>SHOW_CONTEXT</varname> were
set to <literal>always</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ev <optional> <replaceable class="parameter">view_name</replaceable> <optional> <replaceable class="parameter">line_number</replaceable> </optional> </optional> </literal></term>
<listitem>
<para>
This command fetches and edits the definition of the named view,
in the form of a <command>CREATE OR REPLACE VIEW</command> command.
Editing is done in the same way as for <literal>\edit</literal>.
If you quit the editor without saving, the statement is discarded.
If you save and exit the editor, the updated command is executed immediately
if you added a semicolon to it. Otherwise it is redisplayed;
type semicolon or <literal>\g</literal> to send it, or <literal>\r</literal>
to cancel.
</para>
<para>
If no view is specified, a blank <command>CREATE VIEW</command>
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 view definition.
</para>
<para>
Unlike most other meta-commands, the entire remainder of the line is
always taken to be the argument(s) of <command>\ev</command>, and neither
variable interpolation nor backquote expansion are performed in the
arguments.
</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>). It is equivalent to
<command>\pset fieldsep</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\g [ (<replaceable class="parameter">option</replaceable>=<replaceable class="parameter">value</replaceable> [...]) ] [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
<term><literal>\g [ (<replaceable class="parameter">option</replaceable>=<replaceable class="parameter">value</replaceable> [...]) ] [ |<replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
Sends the current query buffer to the server for execution.
</para>
<para>
If parentheses appear after <literal>\g</literal>, they surround a
space-separated list
of <replaceable class="parameter">option</replaceable><literal>=</literal><replaceable class="parameter">value</replaceable>
formatting-option clauses, which are interpreted in the same way
as <literal>\pset</literal>
<replaceable class="parameter">option</replaceable>
<replaceable class="parameter">value</replaceable> commands, but take
effect only for the duration of this query. In this list, spaces are
not allowed around <literal>=</literal> signs, but are required
between option clauses.
If <literal>=</literal><replaceable class="parameter">value</replaceable>
is omitted, the
named <replaceable class="parameter">option</replaceable> is changed
in the same way as for
<literal>\pset</literal> <replaceable class="parameter">option</replaceable>
with no explicit <replaceable class="parameter">value</replaceable>.
</para>
<para>
If a <replaceable class="parameter">filename</replaceable>
or <literal>|</literal><replaceable class="parameter">command</replaceable>
argument is given, the query's output is written to the named
file or piped to the given shell command, instead of displaying it as
usual. 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>
If the current query buffer is empty, the most recently sent query is
re-executed instead. Except for that behavior, <literal>\g</literal>
without any arguments is essentially equivalent to a semicolon.
With arguments, <literal>\g</literal> provides
a <quote>one-shot</quote> alternative to the <command>\o</command>
command, and additionally allows one-shot adjustments of the
output formatting options normally set by <literal>\pset</literal>.
</para>
<para>
When the last argument begins with <literal>|</literal>, the entire
remainder of the line is taken to be
the <replaceable class="parameter">command</replaceable> to execute,
and neither variable interpolation nor backquote expansion are
performed in it. The rest of the line is simply passed literally to
the shell.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\gdesc</literal></term>
<listitem>
<para>
Shows the description (that is, the column names and data types)
of the result of the current query buffer. The query is not
actually executed; however, if it contains some type of syntax
error, that error will be reported in the normal way.
</para>
<para>
If the current query buffer is empty, the most recently sent query
is described instead.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\gexec</literal></term>
<listitem>
<para>
Sends the current query buffer to the server, then treats
each column of each row of the query's output (if any) as a SQL
statement to be executed. For example, to create an index on each
column of <structname>my_table</structname>:
<programlisting>
=&gt; <userinput>SELECT format('create index on my_table(%I)', attname)</userinput>
-&gt; <userinput>FROM pg_attribute</userinput>
-&gt; <userinput>WHERE attrelid = 'my_table'::regclass AND attnum &gt; 0</userinput>
-&gt; <userinput>ORDER BY attnum</userinput>
-&gt; <userinput>\gexec</userinput>
CREATE INDEX
CREATE INDEX
CREATE INDEX
CREATE INDEX
</programlisting>
</para>
<para>
The generated queries are executed in the order in which the rows
are returned, and left-to-right within each row if there is more
than one column. NULL fields are ignored. The generated queries
are sent literally to the server for processing, so they cannot be
<application>psql</application> meta-commands nor contain <application>psql</application>
variable references. If any individual query fails, execution of
the remaining queries continues
unless <varname>ON_ERROR_STOP</varname> is set. Execution of each
query is subject to <varname>ECHO</varname> processing.
(Setting <varname>ECHO</varname> to <literal>all</literal>
or <literal>queries</literal> is often advisable when
using <command>\gexec</command>.) Query logging, single-step mode,
timing, and other query execution features apply to each generated
query as well.
</para>
<para>
If the current query buffer is empty, the most recently sent query
is re-executed instead.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\gset [ <replaceable class="parameter">prefix</replaceable> ]</literal></term>
<listitem>
<para>
Sends the current query buffer to the server and stores the
query's output into <application>psql</application> variables
(see <xref linkend="app-psql-variables"/> below).
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>
<para>
If the current query buffer is empty, the most recently sent query
is re-executed instead.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\gx [ (<replaceable class="parameter">option</replaceable>=<replaceable class="parameter">value</replaceable> [...]) ] [ <replaceable class="parameter">filename</replaceable> ]</literal></term>
<term><literal>\gx [ (<replaceable class="parameter">option</replaceable>=<replaceable class="parameter">value</replaceable> [...]) ] [ |<replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
<literal>\gx</literal> is equivalent to <literal>\g</literal>, except
that it forces expanded output mode for this query, as
if <literal>expanded=on</literal> were included in the list of
<literal>\pset</literal> options. See also <literal>\x</literal>.
</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>
<para>
Unlike most other meta-commands, the entire remainder of the line is
always taken to be the argument(s) of <command>\help</command>, and neither
variable interpolation nor backquote expansion are performed in the
arguments.
</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</command> 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 id="psql-metacommand-if">
<term><literal>\if</literal> <replaceable class="parameter">expression</replaceable></term>
<term><literal>\elif</literal> <replaceable class="parameter">expression</replaceable></term>
<term><literal>\else</literal></term>
<term><literal>\endif</literal></term>
<listitem>
<para>
This group of commands implements nestable conditional blocks.
A conditional block must begin with an <command>\if</command> and end
with an <command>\endif</command>. In between there may be any number
of <command>\elif</command> clauses, which may optionally be followed
by a single <command>\else</command> clause. Ordinary queries and
other types of backslash commands may (and usually do) appear between
the commands forming a conditional block.
</para>
<para>
The <command>\if</command> and <command>\elif</command> commands read
their argument(s) and evaluate them as a boolean expression. If the
expression yields <literal>true</literal> then processing continues
normally; otherwise, lines are skipped until a
matching <command>\elif</command>, <command>\else</command>,
or <command>\endif</command> is reached. Once
an <command>\if</command> or <command>\elif</command> test has
succeeded, the arguments of later <command>\elif</command> commands in
the same block are not evaluated but are treated as false. Lines
following an <command>\else</command> are processed only if no earlier
matching <command>\if</command> or <command>\elif</command> succeeded.
</para>
<para>
The <replaceable class="parameter">expression</replaceable> argument
of an <command>\if</command> or <command>\elif</command> command
is subject to variable interpolation and backquote expansion, just
like any other backslash command argument. After that it is evaluated
like the value of an on/off option variable. So a valid value
is any unambiguous case-insensitive match for one of:
<literal>true</literal>, <literal>false</literal>, <literal>1</literal>,
<literal>0</literal>, <literal>on</literal>, <literal>off</literal>,
<literal>yes</literal>, <literal>no</literal>. For example,
<literal>t</literal>, <literal>T</literal>, and <literal>tR</literal>
will all be considered to be <literal>true</literal>.
</para>
<para>
Expressions that do not properly evaluate to true or false will
generate a warning and be treated as false.
</para>
<para>
Lines being skipped are parsed normally to identify queries and
backslash commands, but queries are not sent to the server, and
backslash commands other than conditionals
(<command>\if</command>, <command>\elif</command>,
<command>\else</command>, <command>\endif</command>) are
ignored. Conditional commands are checked only for valid nesting.
Variable references in skipped lines are not expanded, and backquote
expansion is not performed either.
</para>
<para>
All the backslash commands of a given conditional block must appear in
the same source file. If EOF is reached on the main input file or an
<command>\include</command>-ed file before all local
<command>\if</command>-blocks have been closed,
then <application>psql</application> will raise an error.
</para>
<para>
Here is an example:
</para>
<programlisting>
-- check for the existence of two separate records in the database and store
-- the results in separate psql variables
SELECT
EXISTS(SELECT 1 FROM customer WHERE customer_id = 123) as is_customer,
EXISTS(SELECT 1 FROM employee WHERE employee_id = 456) as is_employee
\gset
\if :is_customer
SELECT * FROM customer WHERE customer_id = 123;
\elif :is_employee
\echo 'is not a customer but is an employee'
SELECT * FROM employee WHERE employee_id = 456;
\else
\if yes
\echo 'not a customer or employee'
\else
\echo 'this will never print'
\endif
\endif
</programlisting>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ir</literal> or <literal>\include_relative</literal> <replaceable class="parameter">filename</replaceable></term>
<listitem>
<para>
The <literal>\ir</literal> command is similar to <literal>\i</literal>, 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>
If the argument begins with <literal>|</literal>, then the entire remainder
of the line is taken to be
the <replaceable class="parameter">command</replaceable> to execute,
and neither variable interpolation nor backquote expansion are
performed in it. The rest of the line is simply passed literally to
the shell.
</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.
If the current query buffer is empty, the most recently executed query
is printed instead.
</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> 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</replaceable>.
An optional prompt string, <replaceable
class="parameter">text</replaceable>, can be specified. (For multiword
prompts, surround the text with single quotes.)
</para>
<para>
By default, <literal>\prompt</literal> uses the terminal for input and
output. However, if the <option>-f</option> command line switch was
used, <literal>\prompt</literal> 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</literal> 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</envar>, or the detected screen width
if <envar>COLUMNS</envar> is not set.
In addition, if <literal>columns</literal> is zero then the
<literal>wrapped</literal> format only affects screen output.
If <literal>columns</literal> is nonzero then file and pipe output is
wrapped to that width as well.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>csv_fieldsep</literal></term>
<listitem>
<para>
Specifies the field separator to be used in
<acronym>CSV</acronym> output format. If the separator character
appears in a field's value, that field is output within double
quotes, following standard <acronym>CSV</acronym> rules.
The default is a comma.
</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 has more than one
column and 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-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</replaceable> 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>aligned</literal>,
<literal>asciidoc</literal>,
<literal>csv</literal>,
<literal>html</literal>,
<literal>latex</literal>,
<literal>latex-longtable</literal>, <literal>troff-ms</literal>,
<literal>unaligned</literal>, or <literal>wrapped</literal>.
Unique abbreviations are allowed.
</para>
<para><literal>aligned</literal> format is the standard,
human-readable, nicely formatted text output; this is the default.
</para>
<para><literal>unaligned</literal> 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. However, the field separator character is not treated
specially if it appears in a column's value;
so <acronym>CSV</acronym> format may be better suited for such
purposes.
</para>
<para><literal>csv</literal> format
<indexterm>
<primary>CSV (Comma-Separated Values) format</primary>
<secondary>in psql</secondary>
</indexterm>
writes column values separated by commas, applying the quoting
rules described in
<ulink url="https://tools.ietf.org/html/rfc4180">RFC 4180</ulink>.
This output is compatible with the CSV format of the server's
<command>COPY</command> command.
A header line with column names is generated unless
the <literal>tuples_only</literal> parameter is
<literal>on</literal>. Titles and footers are not printed.
Each row is terminated by the system-dependent end-of-line character,
which is typically a single newline (<literal>\n</literal>) for
Unix-like systems or a carriage return and newline sequence
(<literal>\r\n</literal>) for Microsoft Windows.
Field separator characters other than comma can be selected with
<command>\pset csv_fieldsep</command>.
</para>
<para><literal>wrapped</literal> format is like <literal>aligned</literal> 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</literal> option. Note that <application>psql</application> will
not attempt to wrap column header titles; therefore,
<literal>wrapped</literal> format behaves the same as <literal>aligned</literal>
if the total width needed for column headers exceeds the target.
</para>
<para>
The <literal>asciidoc</literal>, <literal>html</literal>,
<literal>latex</literal>, <literal>latex-longtable</literal>, and
<literal>troff-ms</literal> 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.
The <literal>latex</literal> format
uses <application>LaTeX</application>'s <literal>tabular</literal>
environment.
The <literal>latex-longtable</literal> format
requires the <application>LaTeX</application>
<literal>longtable</literal> and <literal>booktabs</literal> 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</literal>.
This option only affects the <literal>aligned</literal> and
<literal>wrapped</literal> 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>.</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</acronym>
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>;</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</literal> 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</application>
help output. If the environment variable <envar>PSQL_PAGER</envar>
or <envar>PAGER</envar> is set, the output is piped to the
specified program. Otherwise a platform-dependent default program
(such as <filename>more</filename>) is used.
</para>
<para>
When the <literal>pager</literal> option is <literal>off</literal>, the pager
program is not used. When the <literal>pager</literal> option is
<literal>on</literal>, 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</literal> option can also be set to <literal>always</literal>,
which causes the pager to be used for all terminal output regardless
of whether it fits on the screen. <literal>\pset pager</literal>
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</literal> 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'</literal>. Unspecified output columns
use the last specified value.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>title</literal> (or <literal>C</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
<xref linkend="app-psql-examples"/>, below.
</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</application> 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 to an empty-string value. To
unset a variable, use the <command>\unset</command> command.
</para>
<para><command>\set</command> without any arguments displays the names and values
of all currently-set <application>psql</application> variables.
</para>
<para>
Valid variable names can contain letters, digits, and
underscores. See <xref linkend="app-psql-variables"/> below for details.
Variable names are case-sensitive.
</para>
<para>
Certain variables are special, in that they
control <application>psql</application>'s behavior or are
automatically set to reflect connection state. These variables are
documented in <xref linkend="app-psql-variables"/>, below.
</para>
<note>
<para>
This command is unrelated to the <acronym>SQL</acronym>
command <link linkend="sql-set"><command>SET</command></link>.
</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</replaceable> </literal></term>
<listitem>
<para>
This command fetches and shows the definition of the named function or procedure,
in the form of a <command>CREATE OR REPLACE FUNCTION</command> or
<command>CREATE OR REPLACE PROCEDURE</command> 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)</literal>.
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>
<para>
Unlike most other meta-commands, the entire remainder of the line is
always taken to be the argument(s) of <command>\sf</command>, and neither
variable interpolation nor backquote expansion are performed in the
arguments.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\sv[+] <replaceable class="parameter">view_name</replaceable> </literal></term>
<listitem>
<para>
This command fetches and shows the definition of the named view,
in the form of a <command>CREATE OR REPLACE VIEW</command> command.
The definition is printed to the current query output channel,
as set by <command>\o</command>.
</para>
<para>
If <literal>+</literal> is appended to the command name, then the
output lines are numbered from 1.
</para>
<para>
Unlike most other meta-commands, the entire remainder of the line is
always taken to be the argument(s) of <command>\sv</command>, and neither
variable interpolation nor backquote expansion are performed in the
arguments.
</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>
With a parameter, turns displaying of how long each SQL statement
takes on or off. Without a parameter, toggles the display between
on and off. The display is in milliseconds; intervals longer than
1 second are also shown in minutes:seconds format, with hours and
days fields added if needed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\unset <replaceable class="parameter">name</replaceable></literal></term>
<listitem>
<para>
Unsets (deletes) the <application>psql</application> variable <replaceable
class="parameter">name</replaceable>.
</para>
<para>
Most variables that control <application>psql</application>'s behavior
cannot be unset; instead, an <literal>\unset</literal> command is interpreted
as setting them to their default values.
See <xref linkend="app-psql-variables"/> below.
</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>|</literal><replaceable class="parameter">command</replaceable></term>
<listitem>
<para>
Writes the current query buffer to the file <replaceable
class="parameter">filename</replaceable> or pipes it to the shell
command <replaceable class="parameter">command</replaceable>.
If the current query buffer is empty, the most recently executed query
is written instead.
</para>
<para>
If the argument begins with <literal>|</literal>, then the entire remainder
of the line is taken to be
the <replaceable class="parameter">command</replaceable> to execute,
and neither variable interpolation nor backquote expansion are
performed in it. The rest of the line is simply passed literally to
the shell.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\warn <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 <application>psql</application>'s
standard error channel, rather than standard output.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\watch [ <replaceable class="parameter">seconds</replaceable> ]</literal></term>
<listitem>
<para>
Repeatedly execute the current query buffer (as <literal>\g</literal> does)
until interrupted or the query fails. Wait the specified number of
seconds (default 2) between executions. Each query result is
displayed with a header that includes the <literal>\pset title</literal>
string (if any), the time as of query start, and the delay interval.
</para>
<para>
If the current query buffer is empty, the most recently sent query
is re-executed instead.
</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>
With no argument, escapes to a sub-shell; <application>psql</application>
resumes when the sub-shell exits. With an argument, executes the
shell command <replaceable class="parameter">command</replaceable>.
</para>
<para>
Unlike most other meta-commands, the entire remainder of the line is
always taken to be the argument(s) of <command>\!</command>, and neither
variable interpolation nor backquote expansion are performed in the
arguments. The rest of the line is simply passed literally to the
shell.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\? [ <replaceable class="parameter">topic</replaceable> ]</literal></term>
<listitem>
<para>
Shows help information. The optional
<replaceable class="parameter">topic</replaceable> parameter
(defaulting to <literal>commands</literal>) selects which part of <application>psql</application> is
explained: <literal>commands</literal> describes <application>psql</application>'s
backslash commands; <literal>options</literal> describes the command-line
options that can be passed to <application>psql</application>;
and <literal>variables</literal> shows help about <application>psql</application> configuration
variables.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\;</literal></term>
<listitem>
<para>
Backslash-semicolon is not a meta-command in the same way as the
preceding commands; rather, it simply causes a semicolon to be
added to the query buffer without any further processing.
</para>
<para>
Normally, <application>psql</application> will dispatch a SQL command to the
server as soon as it reaches the command-ending semicolon, even if
more input remains on the current line. Thus for example entering
<programlisting>
select 1; select 2; select 3;
</programlisting>
will result in the three SQL commands being individually sent to
the server, with each one's results being displayed before
continuing to the next command. However, a semicolon entered
as <literal>\;</literal> will not trigger command processing, so that the
command before it and the one after are effectively combined and
sent to the server in one request. So for example
<programlisting>
select 1\; select 2\; select 3;
</programlisting>
results in sending the three SQL commands to the server in a single
request, when the non-backslashed semicolon is reached.
The server executes such a request as a single transaction,
unless there are explicit <command>BEGIN</command>/<command>COMMIT</command>
commands included in the string to divide it into multiple
transactions. (See <xref linkend="protocol-flow-multi-statement"/>
for more details about how the server handles multi-query strings.)
<application>psql</application> prints only the last query result
it receives for each request; in this example, although all
three <command>SELECT</command>s are indeed executed, <application>psql</application>
only prints the <literal>3</literal>.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<refsect3 id="app-psql-patterns" xreflabel="Patterns">
<title>Patterns</title>
<indexterm>
<primary>patterns</primary>
<secondary>in psql and pg_dump</secondary>
</indexterm>
<para>
The various <literal>\d</literal> 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</literal> will display the table named
<literal>foo</literal>. 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"</literal> will display the table named
<literal>FOO"BAR</literal> (not <literal>foo"bar</literal>). 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</literal> will display
the table named <literal>fooFOObar</literal>.
</para>
<para>
Whenever the <replaceable class="parameter">pattern</replaceable> parameter
is omitted completely, the <literal>\d</literal> commands display all objects
that are visible in the current schema search path &mdash; this is
equivalent to using <literal>*</literal> as the pattern.
(An object is said to be <firstterm>visible</firstterm> 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>*.*</literal> as the pattern.
</para>
<para>
Within a pattern, <literal>*</literal> matches any sequence of characters
(including no characters) and <literal>?</literal> matches any single character.
(This notation is comparable to Unix shell file name patterns.)
For example, <literal>\dt int*</literal> displays tables whose names
begin with <literal>int</literal>. But within double quotes, <literal>*</literal>
and <literal>?</literal> lose these special meanings and are just matched
literally.
</para>
<para>
A pattern that contains a dot (<literal>.</literal>) is interpreted as a schema
name pattern followed by an object name pattern. For example,
<literal>\dt foo*.*bar*</literal> displays all tables whose table name
includes <literal>bar</literal> that are in schemas whose schema name
starts with <literal>foo</literal>. 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]</literal> to match any digit. All regular
expression special characters work as specified in
<xref linkend="functions-posix-regexp"/>, except for <literal>.</literal> which
is taken as a separator as mentioned above, <literal>*</literal> which is
translated to the regular-expression notation <literal>.*</literal>,
<literal>?</literal> which is translated to <literal>.</literal>, and
<literal>$</literal> which is matched literally. You can emulate
these pattern characters at need by writing
<literal>?</literal> for <literal>.</literal>,
<literal>(<replaceable class="parameter">R</replaceable>+|)</literal> for
<literal><replaceable class="parameter">R</replaceable>*</literal>, or
<literal>(<replaceable class="parameter">R</replaceable>|)</literal> for
<literal><replaceable class="parameter">R</replaceable>?</literal>.
<literal>$</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>$</literal>
is automatically appended to your pattern). Write <literal>*</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</literal>).
</para>
</refsect3>
</refsect2>
<refsect2>
<title>Advanced Features</title>
<refsect3 id="app-psql-variables" xreflabel="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"/>, below.
</para>
<para>
If you call <command>\set</command> without a second argument, the
variable is set to an empty-string 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>.
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.
</para>
<para>
Variables that control <application>psql</application>'s behavior
generally cannot be unset or set to invalid values. An <literal>\unset</literal>
command is allowed but is interpreted as setting the variable to its
default value. A <literal>\set</literal> command without a second argument is
interpreted as setting the variable to <literal>on</literal>, for control
variables that accept that value, and is rejected for others. Also,
control variables that accept the values <literal>on</literal>
and <literal>off</literal> will also accept other common spellings of Boolean
values, such as <literal>true</literal> and <literal>false</literal>.
</para>
<para>
The specially treated variables are:
</para>
<variablelist>
<varlistentry>
<term>
<varname>AUTOCOMMIT</varname>
<indexterm>
<primary>autocommit</primary>
<secondary>psql</secondary>
</indexterm>
</term>
<listitem>
<para>
When <literal>on</literal> (the default), each SQL command is automatically
committed upon successful completion. To postpone commit in this
mode, you must enter a <command>BEGIN</command> or <command>START
TRANSACTION</command> SQL command. When <literal>off</literal> or unset, SQL
commands are not committed until you explicitly issue
<command>COMMIT</command> or <command>END</command>. The autocommit-off
mode works by issuing an implicit <command>BEGIN</command> for you, just
before any command that is not already in a transaction block and
is not itself a <command>BEGIN</command> or other transaction-control
command, nor a command that cannot be executed inside a transaction
block (such as <command>VACUUM</command>).
</para>
<note>
<para>
In autocommit-off mode, you must explicitly abandon any failed
transaction by entering <command>ABORT</command> or <command>ROLLBACK</command>.
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</productname>'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 changed or 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 to select this behavior is
<option>-e</option>. If set to <literal>errors</literal>, then only
failed queries are displayed on standard error output. The switch
for this behavior is <option>-b</option>. If set to
<literal>none</literal> (the default), 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</literal> 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
this variable to the value <literal>noexec</literal>, the queries are
just shown but are not actually sent to the server and executed.
The default value is <literal>off</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ENCODING</varname></term>
<listitem>
<para>
The current client character set encoding.
This is set every time you connect to a database (including
program start-up), and when you change the encoding
with <literal>\encoding</literal>, but it can be changed or unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ERROR</varname></term>
<listitem>
<para>
<literal>true</literal> if the last SQL query failed, <literal>false</literal> if
it succeeded. See also <varname>SQLSTATE</varname>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>FETCH_COUNT</varname></term>
<listitem>
<para>
If this variable is set to an integer value greater than zero,
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</literal> 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>HIDE_TOAST_COMPRESSION</varname></term>
<listitem>
<para>
If this variable is set to <literal>true</literal>, column
compression method details are not displayed. This is mainly
useful for regression tests.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HIDE_TABLEAM</varname></term>
<listitem>
<para>
If this variable is set to <literal>true</literal>, a table's access
method details are not displayed. This is mainly useful for
regression tests.
</para>
</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
set to <literal>none</literal> (the default), 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. If unset,
the file name is taken from the <envar>PSQL_HISTORY</envar>
environment variable. If that is not set either, the default
is <filename>~/.psql_history</filename>,
or <filename>%APPDATA%\postgresql\psql_history</filename> on Windows.
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 maximum number of commands to store in the command history
(default 500). If set to a negative value, no limit is applied.
</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 changed or unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>IGNOREEOF</varname></term>
<listitem>
<para>
If set to 1 or less, sending an <acronym>EOF</acronym> character (usually
<keycombo action="simul"><keycap>Control</keycap><keycap>D</keycap></keycombo>)
to an interactive session of <application>psql</application>
will terminate the application. If set to a larger numeric value,
that many consecutive <acronym>EOF</acronym> characters must be typed to
make an interactive session terminate. If the variable is set to a
non-numeric value, it is interpreted as 10. The default is 0.
</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.
<productname>PostgreSQL</productname> servers since version 12 do not
support OID system columns anymore, thus LASTOID will always be 0
following <command>INSERT</command> when targeting such servers.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>LAST_ERROR_MESSAGE</varname></term>
<term><varname>LAST_ERROR_SQLSTATE</varname></term>
<listitem>
<para>
The primary error message and associated SQLSTATE code for the most
recent failed query in the current <application>psql</application> session, or
an empty string and <literal>00000</literal> if no error has occurred in
the current session.
</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</literal>, if a statement in a transaction block
generates an error, the error is ignored and the transaction
continues. When set to <literal>interactive</literal>, such errors are only
ignored in interactive sessions, and not when reading script
files. When set to <literal>off</literal> (the default), 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</command> 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</literal>, 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 changed or 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"/> below.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>QUIET</varname></term>
<listitem>
<para>
Setting this variable to <literal>on</literal> 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>ROW_COUNT</varname></term>
<listitem>
<para>
The number of rows returned or affected by the last SQL query, or 0
if the query failed or did not report a row count.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SERVER_VERSION_NAME</varname></term>
<term><varname>SERVER_VERSION_NUM</varname></term>
<listitem>
<para>
The server's version number as a string, for
example <literal>9.6.2</literal>, <literal>10.1</literal> or <literal>11beta1</literal>,
and in numeric form, for
example <literal>90602</literal> or <literal>100001</literal>.
These are set every time you connect to a database
(including program start-up), but can be changed or unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SHOW_CONTEXT</varname></term>
<listitem>
<para>
This variable can be set to the
values <literal>never</literal>, <literal>errors</literal>, or <literal>always</literal>
to control whether <literal>CONTEXT</literal> fields are displayed in
messages from the server. The default is <literal>errors</literal> (meaning
that context will be shown in error messages, but not in notice or
warning messages). This setting has no effect
when <varname>VERBOSITY</varname> is set to <literal>terse</literal>
or <literal>sqlstate</literal>.
(See also <command>\errverbose</command>, for use when you want a verbose
version of the error you just got.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SINGLELINE</varname></term>
<listitem>
<para>
Setting this variable to <literal>on</literal> 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</literal> is equivalent to the command
line option <option>-s</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SQLSTATE</varname></term>
<listitem>
<para>
The error code (see <xref linkend="errcodes-appendix"/>) associated
with the last SQL query's failure, or <literal>00000</literal> if it
succeeded.
</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 changed or unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>VERBOSITY</varname></term>
<listitem>
<para>
This variable can be set to the values <literal>default</literal>,
<literal>verbose</literal>, <literal>terse</literal>,
or <literal>sqlstate</literal> to control the verbosity of error
reports.
(See also <command>\errverbose</command>, for use when you want a verbose
version of the error you just got.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>VERSION</varname></term>
<term><varname>VERSION_NAME</varname></term>
<term><varname>VERSION_NUM</varname></term>
<listitem>
<para>
These variables are set at program start-up to reflect
<application>psql</application>'s version, respectively as a verbose string,
a short string (e.g., <literal>9.6.2</literal>, <literal>10.1</literal>,
or <literal>11beta1</literal>), and a number (e.g., <literal>90602</literal>
or <literal>100001</literal>). They can be changed or unset.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect3>
<refsect3 id="app-psql-interpolation" xreflabel="SQL 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'</literal> 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 <literal>:{?<replaceable>name</replaceable>}</literal> special syntax returns TRUE
or FALSE depending on whether the variable exists or not, and is thus
always substituted, unless the colon is backslash-escaped.
</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" xreflabel="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>%p</literal></term>
<listitem>
<para>The process ID of the backend currently connected to.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%R</literal></term>
<listitem>
<para>
In prompt 1 normally <literal>=</literal>,
but <literal>@</literal> if the session is in an inactive branch of a
conditional block, or <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>*</literal> when in a transaction block, or
<literal>!</literal> when in a failed transaction block, or <literal>?</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</literal>.
</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
<xref linkend="app-psql-variables"/>, above, 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>
<varlistentry>
<term><literal>%w</literal></term>
<listitem>
<para>
Whitespace of the same width as the most recent output of
<varname>PROMPT1</varname>. This can be used as a
<varname>PROMPT2</varname> setting, so that multi-line statements are
aligned with the first line, but there is no visible secondary prompt.
</para>
</listitem>
</varlistentry>
</variablelist>
To insert a percent sign into your prompt, write
<literal>%%</literal>. The default prompts are
<literal>'%/%R%x%# '</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</literal>.
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" xreflabel="Environment">
<title>Environment</title>
<variablelist>
<varlistentry>
<term><envar>COLUMNS</envar></term>
<listitem>
<para>
If <literal>\pset columns</literal> is zero, controls the
width for the <literal>wrapped</literal> 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>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>PG_COLOR</envar></term>
<listitem>
<para>
Specifies whether to use color in diagnostic messages. Possible values
are <literal>always</literal>, <literal>auto</literal> and
<literal>never</literal>.
</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>, <command>\ef</command>,
and <command>\ev</command> commands.
These variables are examined in the order listed;
the first that is set is used.
If none of them is set, the default is to use <filename>vi</filename>
on Unix systems or <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>, <command>\ef</command>, or
<command>\ev</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</productname> or
<productname>vi</productname>, 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>PSQL_PAGER</envar></term>
<term><envar>PAGER</envar></term>
<listitem>
<para>
If a query's results do not fit on the screen, they are piped
through this command. Typical values are <literal>more</literal>
or <literal>less</literal>.
Use of the pager can be disabled by setting <envar>PSQL_PAGER</envar>
or <envar>PAGER</envar> to an empty string, or by adjusting the
pager-related options of the <command>\pset</command> command.
These variables are examined in the order listed;
the first that is set is used.
If none of them is set, the default is to use <literal>more</literal> on most
platforms, but <literal>less</literal> on Cygwin.
</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</productname> utilities,
also uses the environment variables supported by <application>libpq</application>
(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> 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</quote> directory,
which is most reliably identified by running <literal>pg_config
--sysconfdir</literal>. By default this directory will be <filename>../etc/</filename>
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 <varname>HISTFILE</varname> <application>psql</application> variable or
the <envar>PSQL_HISTORY</envar> environment variable.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Notes</title>
<itemizedlist>
<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</application>
itself. However, backslash commands of the <literal>\d</literal> family should
work with servers of versions back to 7.4, though not necessarily with
servers newer than <application>psql</application> 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 around a copy of <application>psql</application> from each
major version and be sure to use the version that matches the
respective server. But in practice, this additional complication should
not be necessary.
</para>
</listitem>
<listitem>
<para>
Before <productname>PostgreSQL</productname> 9.6,
the <option>-c</option> option implied <option>-X</option>
(<option>--no-psqlrc</option>); this is no longer the case.
</para>
</listitem>
<listitem>
<para>
Before <productname>PostgreSQL</productname> 8.4,
<application>psql</application> allowed the
first argument of a single-letter backslash command to start
directly after the command, without intervening whitespace.
Now, some whitespace is required.
</para>
</listitem>
</itemizedlist>
</refsect1>
<refsect1>
<title>Notes for Windows Users</title>
<para>
<application>psql</application> is built as a <quote>console
application</quote>. 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</literal>, because the
raster font does not work with the ANSI code page.
</para>
</listitem>
</itemizedlist></para>
</refsect1>
<refsect1 id="app-psql-examples" xreflabel="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 "public.my_table"
Column | Type | Collation | Nullable | Default
--------+---------+-----------+----------+---------
first | integer | | not null | 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 csv</userinput>
Output format is csv.
peter@localhost testdb=&gt; <userinput>\pset tuples_only</userinput>
Tuples only is on.
peter@localhost testdb=&gt; <userinput>SELECT second, first FROM my_table;</userinput>
one,1
two,2
three,3
four,4
peter@localhost testdb=&gt; <userinput>\pset format unaligned</userinput>
Output format is unaligned.
peter@localhost testdb=&gt; <userinput>\pset fieldsep '\t'</userinput>
Field separator is " ".
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>
<para>
Also, these output format options can be set for just one query by using
<literal>\g</literal>:
<programlisting>
peter@localhost testdb=&gt; <userinput>SELECT * FROM my_table</userinput>
peter@localhost testdb-&gt; <userinput>\g (format=aligned tuples_only=off expanded=on)</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>
<para>
Here is an example of using the <command>\df</command> command to
find only functions with names matching <literal>int*pl</literal>
and whose second argument is of type <type>bigint</type>:
<programlisting>
testdb=&gt; <userinput>\df int*pl * bigint</userinput>
List of functions
Schema | Name | Result data type | Argument data types | Type
------------+---------+------------------+---------------------+------
pg_catalog | int28pl | bigint | smallint, bigint | func
pg_catalog | int48pl | bigint | integer, bigint | func
pg_catalog | int8pl | bigint | bigint, bigint | func
(3 rows)
</programlisting>
</para>
<para>
When suitable, query results can be shown in a crosstab representation
with the <command>\crosstabview</command> command:
<programlisting>
testdb=&gt; <userinput>SELECT first, second, first &gt; 2 AS gt2 FROM my_table;</userinput>
first | second | gt2
-------+--------+-----
1 | one | f
2 | two | f
3 | three | t
4 | four | t
(4 rows)
testdb=&gt; <userinput>\crosstabview first second</userinput>
first | one | two | three | four
-------+-----+-----+-------+------
1 | f | | |
2 | | f | |
3 | | | t |
4 | | | | t
(4 rows)
</programlisting>
This second example shows a multiplication table with rows sorted in reverse
numerical order and columns with an independent, ascending numerical order.
<programlisting>
testdb=&gt; <userinput>SELECT t1.first as "A", t2.first+100 AS "B", t1.first*(t2.first+100) as "AxB",</userinput>
testdb(&gt; <userinput>row_number() over(order by t2.first) AS ord</userinput>
testdb(&gt; <userinput>FROM my_table t1 CROSS JOIN my_table t2 ORDER BY 1 DESC</userinput>
testdb(&gt; <userinput>\crosstabview "A" "B" "AxB" ord</userinput>
A | 101 | 102 | 103 | 104
---+-----+-----+-----+-----
4 | 404 | 408 | 412 | 416
3 | 303 | 306 | 309 | 312
2 | 202 | 204 | 206 | 208
1 | 101 | 102 | 103 | 104
(4 rows)
</programlisting></para>
</refsect1>
</refentry>
View Git Blame Copy Permalink