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doc/src/sgml/ref/psql-ref.sgml
PostgreSQL documentation
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<refentry id="APP-PSQL">
<refmeta>
<refentrytitle id="app-psql-title"><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>
<indexterm zone="app-psql">
<primary>psql</primary>
</indexterm>
<refsynopsisdiv>
<cmdsynopsis>
<command>psql</command>
<arg rep="repeat"><replaceable class="parameter">option</replaceable></arg>
<arg><replaceable class="parameter">dbname</replaceable>
<arg><replaceable class="parameter">username</replaceable></arg></arg>
</cmdsynopsis>
</refsynopsisdiv>
<refsect1>
<title>Description</title>
<para>
<application>psql</application> is a terminal-based front-end to
<productname>PostgreSQL</productname>. It enables you to type in
queries interactively, issue them to
<productname>PostgreSQL</productname>, and see the query results.
Alternatively, input can be from a file. In addition, it provides a
number of meta-commands and various shell-like features to
facilitate writing scripts and automating a wide variety of tasks.
</para>
</refsect1>
<refsect1 id="R1-APP-PSQL-3">
<title>Options</title>
<variablelist>
<varlistentry>
<term><option>-a</></term>
<term><option>--echo-all</></term>
<listitem>
<para>
Print all input lines to standard output as they are read. This is more
useful for script processing than interactive mode. This is
equivalent to setting the variable <varname>ECHO</varname> to
<literal>all</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-A</></term>
<term><option>--no-align</></term>
<listitem>
<para>
Switches to unaligned output mode. (The default output mode is
otherwise aligned.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-c <replaceable class="parameter">command</replaceable></></term>
<term><option>--command <replaceable class="parameter">command</replaceable></></term>
<listitem>
<para>
Specifies that <application>psql</application> is to execute one
command string, <replaceable class="parameter">command</replaceable>,
and then exit. This is useful in shell scripts. Start-up files
(<filename>psqlrc</filename> and <filename>~/.psqlrc</filename>) are
ignored with this option.
</para>
<para>
<replaceable class="parameter">command</replaceable> must be either
a command string that is completely parsable by the server (i.e.,
it contains no <application>psql</application>-specific features),
or a single backslash command. Thus you cannot mix
<acronym>SQL</acronym> and <application>psql</application>
meta-commands with this option. To achieve that, you could
pipe the string into <application>psql</application>, like
this: <literal>echo '\x \\ SELECT * FROM foo;' | psql</literal>.
(<literal>\\</> is the separator meta-command.)
</para>
<para>
If the command string contains multiple SQL commands, they are
processed in a single transaction, unless there are explicit
<command>BEGIN</>/<command>COMMIT</> commands included in the
string to divide it into multiple transactions. This is
different from the behavior when the same string is fed to
<application>psql</application>'s standard input.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-d <replaceable class="parameter">dbname</replaceable></></term>
<term><option>--dbname <replaceable class="parameter">dbname</replaceable></></term>
<listitem>
<para>
Specifies the name of the database to connect to. This is
equivalent to specifying <replaceable
class="parameter">dbname</replaceable> as the first non-option
argument on the command line.
</para>
<para>
If this parameter contains an <symbol>=</symbol> sign, it is treated as a
<parameter>conninfo</parameter> string. See <xref linkend="libpq-connect"> for more information.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-e</></term>
<term><option>--echo-queries</></term>
<listitem>
<para>
Copy all SQL commands sent to the server to standard output as well.
This is equivalent
to setting the variable <varname>ECHO</varname> to
<literal>queries</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-E</></term>
<term><option>--echo-hidden</></term>
<listitem>
<para>
Echo the actual queries generated by <command>\d</command> and other backslash
commands. You can use this to study <application>psql</application>'s
internal operations. This is equivalent to
setting the variable <varname>ECHO_HIDDEN</varname> from within
<application>psql</application>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-f <replaceable class="parameter">filename</replaceable></></term>
<term><option>--file <replaceable class="parameter">filename</replaceable></></term>
<listitem>
<para>
Use the file <replaceable class="parameter">filename</replaceable>
as the source of commands instead of reading commands interactively.
After the file is processed, <application>psql</application>
terminates. This is in many ways equivalent to the internal
command <command>\i</command>.
</para>
<para>
If <replaceable>filename</replaceable> is <literal>-</literal>
(hyphen), then standard input is read.
</para>
<para>
Using this option is subtly different from writing <literal>psql
&lt; <replaceable
class="parameter">filename</replaceable></literal>. In general,
both will do what you expect, but using <literal>-f</literal>
enables some nice features such as error messages with line
numbers. There is also a slight chance that using this option will
reduce the start-up overhead. On the other hand, the variant using
the shell's input redirection is (in theory) guaranteed to yield
exactly the same output you would have received had you entered
everything by hand.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-F <replaceable class="parameter">separator</replaceable></></term>
<term><option>--field-separator <replaceable class="parameter">separator</replaceable></></term>
<listitem>
<para>
Use <replaceable class="parameter">separator</replaceable> as the
field separator for unaligned output. This is equivalent to
<command>\pset fieldsep</command> or <command>\f</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-h <replaceable class="parameter">hostname</replaceable></></term>
<term><option>--host <replaceable class="parameter">hostname</replaceable></></term>
<listitem>
<para>
Specifies the host name of the machine on which the
server is running. If the value begins
with a slash, it is used as the directory for the Unix-domain
socket.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-H</></term>
<term><option>--html</></term>
<listitem>
<para>
Turn on <acronym>HTML</acronym> tabular output. This is
equivalent to <literal>\pset format html</literal> or the
<command>\H</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-l</></term>
<term><option>--list</></term>
<listitem>
<para>
List all available databases, then exit. Other non-connection
options are ignored. This is similar to the internal command
<command>\list</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-L <replaceable class="parameter">filename</replaceable></></term>
<term><option>--log-file <replaceable class="parameter">filename</replaceable></></term>
<listitem>
<para>
Write all query output into file <replaceable
class="parameter">filename</replaceable>, in addition to the
normal output destination.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-n</></term>
<term><option>--no-readline</></term>
<listitem>
<para>
Do not use readline for line editing and do not use the history.
This can be useful to turn off tab expansion when cutting and pasting.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-o <replaceable class="parameter">filename</replaceable></></term>
<term><option>--output <replaceable class="parameter">filename</replaceable></></term>
<listitem>
<para>
Put all query output into file <replaceable
class="parameter">filename</replaceable>. This is equivalent to
the command <command>\o</command>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-p <replaceable class="parameter">port</replaceable></></term>
<term><option>--port <replaceable class="parameter">port</replaceable></></term>
<listitem>
<para>
Specifies the TCP port or the local Unix-domain
socket file extension on which the server is listening for
connections. Defaults to the value of the <envar>PGPORT</envar>
environment variable or, if not set, to the port specified at
compile time, usually 5432.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-P <replaceable class="parameter">assignment</replaceable></></term>
<term><option>--pset <replaceable class="parameter">assignment</replaceable></></term>
<listitem>
<para>
Specifies printing options, in the style of
<command>\pset</command>. Note that here you
have to separate name and value with an equal sign instead of a
space. For example, to set the output format to LaTeX, you could write
<literal>-P format=latex</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-q</></term>
<term><option>--quiet</></term>
<listitem>
<para>
Specifies that <application>psql</application> should do its work
quietly. By default, it prints welcome messages and various
informational output. If this option is used, none of this
happens. This is useful with the <option>-c</option> option.
Within <application>psql</application> you can also set the
<varname>QUIET</varname> variable to achieve the same effect.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-R <replaceable class="parameter">separator</replaceable></></term>
<term><option>--record-separator <replaceable class="parameter">separator</replaceable></></term>
<listitem>
<para>
Use <replaceable class="parameter">separator</replaceable> as the
record separator for unaligned output. This is equivalent to the
<command>\pset recordsep</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-s</></term>
<term><option>--single-step</></term>
<listitem>
<para>
Run in single-step mode. That means the user is prompted before
each command is sent to the server, with the option to cancel
execution as well. Use this to debug scripts.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-S</></term>
<term><option>--single-line</></term>
<listitem>
<para>
Runs in single-line mode where a newline terminates an SQL command, as a
semicolon does.
</para>
<note>
<para>
This mode is provided for those who insist on it, but you are not
necessarily encouraged to use it. In particular, if you mix
<acronym>SQL</acronym> and meta-commands on a line the order of
execution might not always be clear to the inexperienced user.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-t</></term>
<term><option>--tuples-only</></term>
<listitem>
<para>
Turn off printing of column names and result row count footers,
etc. This is equivalent to the <command>\t</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-T <replaceable class="parameter">table_options</replaceable></></term>
<term><option>--table-attr <replaceable class="parameter">table_options</replaceable></></term>
<listitem>
<para>
Specifies options to be placed within the
<acronym>HTML</acronym> <sgmltag>table</sgmltag> tag. See
<command>\pset</command> for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-U <replaceable class="parameter">username</replaceable></></term>
<term><option>--username <replaceable class="parameter">username</replaceable></></term>
<listitem>
<para>
Connect to the database as the user <replaceable
class="parameter">username</replaceable> instead of the default.
(You must have permission to do so, of course.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-v <replaceable class="parameter">assignment</replaceable></></term>
<term><option>--set <replaceable class="parameter">assignment</replaceable></></term>
<term><option>--variable <replaceable class="parameter">assignment</replaceable></></term>
<listitem>
<para>
Perform a variable assignment, like the <command>\set</command>
internal 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 just set a variable without a value,
use the equal sign but leave off the value. These assignments are
done during a very early stage of start-up, so variables reserved
for internal purposes might get overwritten later.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-V</></term>
<term><option>--version</></term>
<listitem>
<para>
Print the <application>psql</application> version and exit.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-w</></term>
<term><option>--no-password</></term>
<listitem>
<para>
Never issue a password prompt. If the server requires password
authentication and a password is not available by other means
such as a <filename>.pgpass</filename> file, the connection
attempt will fail. This option can be useful in batch jobs and
scripts where no user is present to enter a password.
</para>
<para>
Note that this option will remain set for the entire session,
and so it affects uses of the meta-command
<command>\connect</command> as well as the initial connection attempt.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-W</></term>
<term><option>--password</></term>
<listitem>
<para>
Force <application>psql</application> to prompt for a
password before connecting to a database.
</para>
<para>
This option is never essential, since <application>psql</application>
will automatically prompt for a password if the server demands
password authentication. However, <application>psql</application>
will waste a connection attempt finding out that the server wants a
password. In some cases it is worth typing <option>-W</> to avoid
the extra connection attempt.
</para>
<para>
Note that this option will remain set for the entire session,
and so it affects uses of the meta-command
<command>\connect</command> as well as the initial connection attempt.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-x</></term>
<term><option>--expanded</></term>
<listitem>
<para>
Turn on the expanded table formatting mode. This is equivalent to the
<command>\x</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-X,</></term>
<term><option>--no-psqlrc</></term>
<listitem>
<para>
Do not read the start-up file (neither the system-wide
<filename>psqlrc</filename> file nor the user's
<filename>~/.psqlrc</filename> file).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-1</option></term>
<term><option>--single-transaction</option></term>
<listitem>
<para>
When <application>psql</application> executes a script with the
<option>-f</> option, adding this option wraps
<command>BEGIN</>/<command>COMMIT</> around the script to execute it
as a single transaction. This ensures that either all the commands
complete successfully, or no changes are applied.
</para>
<para>
If the script itself uses <command>BEGIN</>, <command>COMMIT</>,
or <command>ROLLBACK</>, this option will not have the desired
effects.
Also, if the script contains any command that cannot be executed
inside a transaction block, specifying this option will cause that
command (and hence the whole transaction) to fail.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><option>-?</></term>
<term><option>--help</></term>
<listitem>
<para>
Show help about <application>psql</application> command line
arguments, and exit.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
<refsect1>
<title>Exit Status</title>
<para>
<application>psql</application> returns 0 to the shell if it
finished normally, 1 if a fatal error of its own occurs (e.g. out of memory,
file not found), 2 if the connection to the server went bad
and the session was not interactive, and 3 if an error occurred in a
script and the variable <varname>ON_ERROR_STOP</varname> was set.
</para>
</refsect1>
<refsect1>
<title>Usage</title>
<refsect2 id="R2-APP-PSQL-connecting">
<title>Connecting To A Database</title>
<para>
<application>psql</application> is a regular
<productname>PostgreSQL</productname> client application. In order
to connect to a database you need to know the name of your target
database, the host name and port number of the server, and what user
name you want to connect as. <application>psql</application> can be
told about those parameters via command line options, namely
<option>-d</option>, <option>-h</option>, <option>-p</option>, and
<option>-U</option> respectively. If an argument is found that does
not belong to any option it will be interpreted as the database name
(or the user name, if the database name is already given). Not all
of these options are required; there are useful defaults. If you omit the host
name, <application>psql</> will connect via a Unix-domain socket
to a server on the local host, or via TCP/IP to <literal>localhost</> on
machines that don't have Unix-domain sockets. The default port number is
determined at compile time.
Since the database server uses the same default, you will not have
to specify the port in most cases. The default user name is your
Unix user name, as is the default database name. Note that you cannot
just connect to any database under any user name. Your database
administrator should have informed you about your access rights.
</para>
<para>
When the defaults aren't quite right, you can save yourself
some typing by setting the environment variables
<envar>PGDATABASE</envar>, <envar>PGHOST</envar>,
<envar>PGPORT</envar> and/or <envar>PGUSER</envar> to appropriate
values. (For additional environment variables, see <xref
linkend="libpq-envars">.) It is also convenient to have a
<filename>~/.pgpass</> file to avoid regularly having to type in
passwords. See <xref linkend="libpq-pgpass"> for more information.
</para>
<para>
An alternative way to specify connection parameters is in a
<parameter>conninfo</parameter> string, 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>
</programlisting>
This way you can also use LDAP for connection parameter lookup as
described in <xref linkend="libpq-ldap">.
See <xref linkend="libpq-connect"> 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>
</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>
Whenever a command is executed, <application>psql</application> also polls
for asynchronous notification events generated by
<xref linkend="SQL-LISTEN" endterm="SQL-LISTEN-title"> and
<xref linkend="SQL-NOTIFY" endterm="SQL-NOTIFY-title">.
</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 into an argument you can quote it with a
single quote. To include a single quote into such an argument,
use two single quotes. Anything contained in single quotes is
furthermore subject to C-like substitutions for
<literal>\n</literal> (new line), <literal>\t</literal> (tab),
<literal>\</literal><replaceable>digits</replaceable> (octal), and
<literal>\x</literal><replaceable>digits</replaceable> (hexadecimal).
</para>
<para>
If an unquoted argument begins with a colon (<literal>:</literal>),
it is taken as a <application>psql</> variable and the value of the
variable is used as the argument instead. If the variable name is
surrounded by single quotes (e.g. <literal>:'var'</literal>), it
will be escaped as an SQL literal and the result will be used as
the argument. If the variable name is surrounded by double quotes,
it will be escaped as an SQL identifier and the result will be used
as the argument.
</para>
<para>
Arguments that are enclosed in backquotes (<literal>`</literal>)
are taken as a command line that is passed to the shell. The
output of the command (with any trailing newline removed) is taken
as the argument value. The above escape sequences also apply in
backquotes.
</para>
<para>
Some commands take an <acronym>SQL</acronym> identifier (such as a
table name) as argument. These arguments follow the syntax rules
of <acronym>SQL</acronym>: Unquoted letters are forced to
lowercase, while double quotes (<literal>"</>) protect letters
from case conversion and allow incorporation of whitespace into
the identifier. Within double quotes, paired double quotes reduce
to a single double quote in the resulting name. For example,
<literal>FOO"BAR"BAZ</> is interpreted as <literal>fooBARbaz</>,
and <literal>"A weird"" name"</> becomes <literal>A weird"
name</>.
</para>
<para>
Parsing for arguments stops at the end of the line, or when another
unquoted backslash is found. An unquoted backslash
is taken as the beginning of a new meta-command. The special
sequence <literal>\\</literal> (two backslashes) marks the end of
arguments and continues parsing <acronym>SQL</acronym> commands, if
any. That way <acronym>SQL</acronym> and
<application>psql</application> commands can be freely mixed on a
line. But in any case, the arguments of a meta-command cannot
continue beyond the end of the line.
</para>
<para>
The following meta-commands are defined:
<variablelist>
<varlistentry>
<term><literal>\a</literal></term>
<listitem>
<para>
If the current table output format is unaligned, it is switched to aligned.
If it is not unaligned, it is set to unaligned. This command is
kept for backwards compatibility. See <command>\pset</command> for a
more general solution.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\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>\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>\connect</literal> (or <literal>\c</literal>) <literal>[ <replaceable class="parameter">dbname</replaceable> [ <replaceable class="parameter">username</replaceable> ] [ <replaceable class="parameter">host</replaceable> ] [ <replaceable class="parameter">port</replaceable> ] ]</literal></term>
<listitem>
<para>
Establishes a new connection to a <productname>PostgreSQL</>
server. If the new connection is successfully made, the
previous connection is closed. If any of <replaceable
class="parameter">dbname</replaceable>, <replaceable
class="parameter">username</replaceable>, <replaceable
class="parameter">host</replaceable> or <replaceable
class="parameter">port</replaceable> are omitted or specified
as <literal>-</literal>, the value of that parameter from the
previous connection is used. If there is no previous
connection, the <application>libpq</application> default for
the parameter's value is used.
</para>
<para>
If the connection attempt failed (wrong user name, access
denied, etc.), the previous connection will only be kept if
<application>psql</application> is in interactive mode. When
executing a non-interactive script, processing will
immediately stop with an error. This distinction was chosen as
a user convenience against typos on the one hand, and a safety
mechanism that scripts are not accidentally acting on the
wrong database on the other hand.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\conninfo</literal></term>
<listitem>
<para>
Outputs information about the current database connection.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\copy { <replaceable class="parameter">table</replaceable> [ ( <replaceable class="parameter">column_list</replaceable> ) ] | ( <replaceable class="parameter">query</replaceable> ) }
{ <literal>from</literal> | <literal>to</literal> }
{ <replaceable class="parameter">filename</replaceable> | stdin | stdout | pstdin | pstdout }
[ with ]
[ binary ]
[ oids ]
[ delimiter [ as ] '<replaceable class="parameter">character</replaceable>' ]
[ null [ as ] '<replaceable class="parameter">string</replaceable>' ]
[ csv
[ header ]
[ quote [ as ] '<replaceable class="parameter">character</replaceable>' ]
[ escape [ as ] '<replaceable class="parameter">character</replaceable>' ]
[ force quote <replaceable class="parameter">column_list</replaceable> | * ]
[ force not null <replaceable class="parameter">column_list</replaceable> ] ]</literal>
</term>
<listitem>
<para>
Performs a frontend (client) copy. This is an operation that
runs an <acronym>SQL</acronym> <xref linkend="SQL-COPY"
endterm="SQL-COPY-title"> 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>
The syntax of the command is similar to that of the
<acronym>SQL</acronym> <xref linkend="sql-copy"
endterm="sql-copy-title"> command. Note that, because of this,
special parsing rules apply to the <command>\copy</command>
command. In particular, the variable substitution rules and
backslash escapes do not apply.
</para>
<para>
<literal>\copy ... from stdin | to stdout</literal>
reads/writes based on the command input and output respectively.
All rows are read from the same source that issued the command,
continuing until <literal>\.</literal> is read or the stream
reaches <acronym>EOF</>. Output is sent to the same place as
command output. To read/write from
<application>psql</application>'s standard input or output, use
<literal>pstdin</> or <literal>pstdout</>. This option is useful
for populating tables in-line within a SQL script file.
</para>
<tip>
<para>
This operation is not as efficient as the <acronym>SQL</acronym>
<command>COPY</command> command because all data must pass
through the client/server connection. For large
amounts of data the <acronym>SQL</acronym> command might be preferable.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\copyright</literal></term>
<listitem>
<para>
Shows the copyright and distribution terms of
<productname>PostgreSQL</productname>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\d[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
For each relation (table, view, index, or sequence) 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.
(<quote>Matching the pattern</> is defined in
<xref linkend="APP-PSQL-patterns" endterm="APP-PSQL-patterns-title">
below.)
</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, and the view definition if the relation is a view.
</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>\dtvsxr</command> which will show a list of
all visible tables, views, sequences, and external tables. This is purely a convenience
measure.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\da[S] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists aggregate functions, together with their
return type and the data types they operate on. If <replaceable
class="parameter">pattern</replaceable>
is specified, only aggregates whose names match the pattern are shown.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\db[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists tablespaces. If <replaceable
class="parameter">pattern</replaceable>
is specified, only tablespaces whose names match the pattern are shown.
If <literal>+</literal> is appended to the command name, each object
is listed with its associated permissions.
</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.
</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.
</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 matching the <replaceable
class="parameter">pattern</replaceable>, or of all visible objects 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.
<quote>Object</quote> covers aggregates, functions, operators,
types, relations (tables, views, indexes, sequences), large
objects, rules, and triggers. For example:
<programlisting>
=&gt; <userinput>\dd version</userinput>
Object descriptions
Schema | Name | Object | Description
------------+---------+----------+---------------------------
pg_catalog | version | function | PostgreSQL version string
(1 row)
</programlisting>
</para>
<para>
Descriptions for objects can be created with the <xref
linkend="sql-comment" endterm="sql-comment-title">
<acronym>SQL</acronym> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ddp [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists default access privilege settings. An entry is shown for
each role (and schema, if applicable) for which the default
privilege settings have been changed from the built-in defaults.
If <replaceable class="parameter">pattern</replaceable> is
specified, only entries whose role name or schema name matches
the pattern are listed.
</para>
<para>
The <xref linkend="sql-alterdefaultprivileges"> command is used to set
default access privileges. The meaning of the
privilege display is explained under
<xref linkend="sql-grant">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dD[S] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists domains. If <replaceable
class="parameter">pattern</replaceable>
is specified, only domains whose names match the pattern are shown.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\des[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists foreign servers (mnemonic: <quote>external
servers</quote>).
If <replaceable class="parameter">pattern</replaceable> is
specified, only those servers whose name matches the pattern
are listed. If the form <literal>\des+</literal> is used, a
full description of each server is shown, including the
server's ACL, type, version, and options.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\deu[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists user mappings (mnemonic: <quote>external
users</quote>).
If <replaceable class="parameter">pattern</replaceable> is
specified, only those mappings whose user names match the
pattern are listed. If the form <literal>\deu+</literal> is
used, additional information about each mapping is shown.
</para>
<caution>
<para>
<literal>\deu+</literal> might also display the user name and
password of the remote user, so care should be taken not to
disclose them.
</para>
</caution>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dew[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists foreign-data wrappers (mnemonic: <quote>external
wrappers</quote>).
If <replaceable class="parameter">pattern</replaceable> is
specified, only those foreign-data wrappers whose name matches
the pattern are listed. If the form <literal>\dew+</literal>
is used, the ACL and options of the foreign-data wrapper are
also shown.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\df[antwS+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists functions, together with their arguments, return types, and
function types, which are classified as <quote>agg</> (aggregate),
<quote>normal</>, <quote>trigger</>, or <quote>window</>.
To display only functions
of specific type(s), add the corresponding letters <literal>a</>,
<literal>n</>, <literal>t</>, or <literal>w</> to the command.
If <replaceable
class="parameter">pattern</replaceable> is specified, only
functions whose names match the pattern are shown. If the
form <literal>\df+</literal> is used, additional information
about each function, including volatility, language, source
code and description, is shown. By default, only user-created
objects are shown; supply a pattern or the <literal>S</literal>
modifier to include system objects.
</para>
<tip>
<para>
To look up functions taking arguments or returning values of a specific
type, use your pager's search capability to scroll through the
<literal>\df</> output.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dF[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search configurations.
If <replaceable class="parameter">pattern</replaceable> is specified,
only configurations whose names match the pattern are shown.
If the form <literal>\dF+</literal> is used, a full description of
each configuration is shown, including the underlying text search
parser and the dictionary list for each parser token type.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dFd[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search dictionaries.
If <replaceable class="parameter">pattern</replaceable> is specified,
only dictionaries whose names match the pattern are shown.
If the form <literal>\dFd+</literal> is used, additional information
is shown about each selected dictionary, including the underlying
text search template and the option values.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dFp[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search parsers.
If <replaceable class="parameter">pattern</replaceable> is specified,
only parsers whose names match the pattern are shown.
If the form <literal>\dFp+</literal> is used, a full description of
each parser is shown, including the underlying functions and the
list of recognized token types.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dFt[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists text search templates.
If <replaceable class="parameter">pattern</replaceable> is specified,
only templates whose names match the pattern are shown.
If the form <literal>\dFt+</literal> is used, additional information
is shown about each template, including the underlying function names.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dg[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists database roles. If <replaceable
class="parameter">pattern</replaceable> is specified, only
those roles whose names match the pattern are listed.
(This command is now effectively the same as <literal>\du</literal>).
If the form <literal>\dg+</literal> is used, additional information
is shown about each role, including the comment for each role.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\di[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>
<term><literal>\dP[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<term><literal>\dx[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<term><literal>\dr[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
In this group of commands, the letters
<literal>i</literal>, <literal>s</literal>,
<literal>t</literal>, <literal>v</literal>,
<literal>P</literal>, <literal>x</literal>, and <literal>r</literal>
stand for index, sequence, table, view, parent table, external table, and foreign table respectively.
You can specify any or all of
these letters, in any order, to obtain a listing of objects
of these types. For example, <literal>\dit</> lists indexes
and tables. If <literal>+</literal> is
appended to the command name, each object is listed with its
physical size on disk and its associated description, if any.
If <replaceable class="parameter">pattern</replaceable> is
specified, only objects whose names match the pattern are listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\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>\dn[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists schemas (namespaces). If <replaceable
class="parameter">pattern</replaceable>
is specified, only schemas whose names match the pattern are listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system objects.
If <literal>+</literal> is appended to the command name, each object
is listed with its associated permissions and description, if any.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\do[S] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists operators with their operand and return types.
If <replaceable class="parameter">pattern</replaceable> is
specified, only operators whose names match the pattern are listed.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dp [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists tables, views and sequences with their
associated access privileges.
If <replaceable class="parameter">pattern</replaceable> is
specified, only tables, views and sequences whose names match the
pattern are listed.
</para>
<para>
The <xref linkend="sql-grant" endterm="sql-grant-title"> and
<xref linkend="sql-revoke" endterm="sql-revoke-title">
commands are used to set access privileges. The meaning of the
privilege display is explained under
<xref linkend="sql-grant">.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\drds [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">role-pattern</replaceable></link> [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">database-pattern</replaceable></link> ] ]</literal></term>
<listitem>
<para>
Lists defined configuration settings. These settings can be
role-specific, database-specific, or both.
<replaceable>role-pattern</replaceable> and
<replaceable>database-pattern</replaceable> are used to select
specific roles and databases to list, respectively. If omitted, or if
<literal>*</> is specified, all settings are listed, including those
not role-specific or database-specific, respectively.
</para>
<para>
The <xref linkend="sql-alterrole"> and
<xref linkend="sql-alterdatabase">
commands are used to define per-role and per-database configuration
settings.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\dT[S+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists data types.
If <replaceable class="parameter">pattern</replaceable> is
specified, only types whose names match the pattern are listed.
If <literal>+</literal> is appended to the command name, each type is
listed with its internal name and size, as well as its allowed values
if it is an <type>enum</> type.
By default, only user-created objects are shown; supply a
pattern or the <literal>S</literal> modifier to include system
objects.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\du[+] [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists database roles. 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, including the comment for each role.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\edit</> (or <literal>\e</>) <literal> <optional> <replaceable class="parameter">filename</> </optional> <optional> <replaceable class="parameter">line_number</> </optional> </literal></term>
<listitem>
<para>
If <replaceable class="parameter">filename</replaceable> is
specified, the file is edited; after the editor exits, its
content is copied back to the query buffer. If no <replaceable
class="parameter">filename</replaceable> is given, the current query
buffer is copied to a temporary file which is then edited in the same
fashion.
</para>
<para>
The new query buffer is then re-parsed according to the normal
rules of <application>psql</application>, where the whole buffer
is treated as a single line. (Thus you cannot make scripts this
way. Use <command>\i</command> for that.) This means that
if the query ends with (or contains) a semicolon, it is
immediately executed. Otherwise it will merely wait in the
query buffer; type semicolon or <literal>\g</> to send it, or
<literal>\r</> to cancel.
</para>
<tip>
<para>
<application>psql</application> checks the environment
variables <envar>PSQL_EDITOR</envar>, <envar>EDITOR</envar>, and
<envar>VISUAL</envar> (in that order) for an editor to use. If
all of them are unset, <filename>vi</filename> is used on Unix
systems, <filename>notepad.exe</filename> on Windows systems.
</para>
</tip>
<para>
If a line number is specified, <application>psql</application> will
position the cursor on the specified line of the file or query buffer.
This feature requires the <varname>EDITOR_LINENUMBER_SWITCH</varname>
variable to be set, so that <application>psql</application> knows how
to specify the line number to the editor. Note that if a single
all-digits argument is given, <application>psql</application> assumes
it is a line number not a file name.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\ef <optional> <replaceable class="parameter">function_description</> <optional> <replaceable class="parameter">line_number</> </optional> </optional> </literal></term>
<listitem>
<para>
This command fetches and edits the definition of the named function,
in the form of a <command>CREATE OR REPLACE FUNCTION</> command.
Editing is done in the same way as for <literal>\edit</>.
After the editor exits, the updated command waits in the query buffer;
type semicolon or <literal>\g</> to send it, or <literal>\r</>
to cancel.
</para>
<para>
The target function can be specified by name alone, or by name
and arguments, for example <literal>foo(integer, text)</>.
The argument types must be given if there is more
than one function of the same name.
</para>
<para>
If no function is specified, a blank <command>CREATE FUNCTION</>
template is presented for editing.
</para>
<para>
If a line number is specified, <application>psql</application> will
position the cursor on the specified line of the function body
(note that the function body typically does not begin on the
first line of the file).
This feature requires the <varname>EDITOR_LINENUMBER_SWITCH</varname>
variable to be set, so that <application>psql</application> knows how
to specify the line number to the editor.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\echo <replaceable class="parameter">text</replaceable> [ ... ]</literal></term>
<listitem>
<para>
Prints the arguments to the standard output, separated by one
space and followed by a newline. This can be useful to
intersperse information in the output of scripts. For example:
<programlisting>
=&gt; <userinput>\echo `date`</userinput>
Tue Oct 26 21:40:57 CEST 1999
</programlisting>
If the first argument is an unquoted <literal>-n</literal> the trailing
newline is not written.
</para>
<tip>
<para>
If you use the <command>\o</command> command to redirect your
query output you might wish to use <command>\qecho</command>
instead of this command.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\encoding [ <replaceable class="parameter">encoding</replaceable> ]</literal></term>
<listitem>
<para>
Sets the client character set encoding. Without an argument, this command
shows the current encoding.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\f [ <replaceable class="parameter">string</replaceable> ]</literal></term>
<listitem>
<para>
Sets the field separator for unaligned query output. The default
is the vertical bar (<literal>|</literal>). See also
<command>\pset</command> for a generic way of setting output
options.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\g</literal> [ { <replaceable class="parameter">filename</replaceable> | <literal>|</literal><replaceable class="parameter">command</replaceable> } ]</term>
<listitem>
<para>
Sends the current query input buffer to the server and
optionally stores the query's output in <replaceable
class="parameter">filename</replaceable> or pipes the output
into a separate Unix shell executing <replaceable
class="parameter">command</replaceable>. A bare
<literal>\g</literal> is virtually equivalent to a semicolon. A
<literal>\g</literal> with argument is a <quote>one-shot</quote>
alternative to the <command>\o</command> command.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\help</literal> (or <literal>\h</literal>) <literal>[ <replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
Gives syntax help on the specified <acronym>SQL</acronym>
command. If <replaceable class="parameter">command</replaceable>
is not specified, then <application>psql</application> will list
all the commands for which syntax help is available. If
<replaceable class="parameter">command</replaceable> is an
asterisk (<literal>*</literal>), then syntax help on all
<acronym>SQL</acronym> commands is shown.
</para>
<note>
<para>
To simplify typing, commands that consists of several words do
not have to be quoted. Thus it is fine to type <userinput>\help
alter table</userinput>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\H</literal></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 <replaceable class="parameter">filename</replaceable></literal></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>
<note>
<para>
If you want to see the lines on the screen as they are read you
must set the variable <varname>ECHO</varname> to
<literal>all</literal>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\l</literal> (or <literal>\list</literal>)</term>
<term><literal>\l+</literal> (or <literal>\list+</literal>)</term>
<listitem>
<para>
List the names, owners, character set encodings, and access privileges
of all the databases in the server.
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> [ {<replaceable class="parameter">filename</replaceable> | <literal>|</literal><replaceable class="parameter">command</replaceable>} ]</term>
<listitem>
<para>
Saves future query results to the file <replaceable
class="parameter">filename</replaceable> or pipes future results
into a separate Unix shell to execute <replaceable
class="parameter">command</replaceable>. If no arguments are
specified, the query output will be reset to the standard output.
</para>
<para>
<quote>Query results</quote> includes all tables, command
responses, and notices obtained from the database server, as
well as output of various backslash commands that query the
database (such as <command>\d</command>), but not error
messages.
</para>
<tip>
<para>
To intersperse text output in between query results, use
<command>\qecho</command>.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\p</literal></term>
<listitem>
<para>
Print the current query buffer to the standard output.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\password [ <replaceable class="parameter">username</replaceable> ]</literal></term>
<listitem>
<para>
Changes the password of the specified user (by default, the current
user). This command prompts for the new password, encrypts it, and
sends it to the server as an <command>ALTER ROLE</> command. This
makes sure that the new password does not appear in cleartext in the
command history, the server log, or elsewhere.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\prompt [ <replaceable class="parameter">text</replaceable> ] <replaceable class="parameter">name</replaceable></literal></term>
<listitem>
<para>
Prompts the user to set variable <replaceable
class="parameter">name</>. An optional prompt, <replaceable
class="parameter">text</>, can be specified. (For multiword
prompts, use single quotes.)
</para>
<para>
By default, <literal>\prompt</> uses the terminal for input and
output. However, if the <option>-f</> command line switch is
used, <literal>\prompt</> uses standard input and standard output.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\pset <replaceable class="parameter">option</replaceable> [ <replaceable class="parameter">value</replaceable> ]</literal></term>
<listitem>
<para>
This command sets options affecting the output of query result tables.
<replaceable class="parameter">option</replaceable>
indicates which option is to be set. The semantics of
<replaceable class="parameter">value</replaceable> vary depending
on the selected option. For some options, omitting <replaceable
class="parameter">value</replaceable> causes the option to be toggled
or unset, as described under the particular option. If no such
behavior is mentioned, then omitting
<replaceable class="parameter">value</replaceable> just results in
the current setting being displayed.
</para>
<para>
Adjustable printing options are:
<variablelist>
<varlistentry>
<term><literal>format</literal></term>
<listitem>
<para>
Sets the output format to one of <literal>unaligned</literal>,
<literal>aligned</literal>, <literal>wrapped</literal>,
<literal>html</literal>,
<literal>latex</literal>, or <literal>troff-ms</literal>.
Unique abbreviations are allowed. (That would mean one letter
is enough.)
</para>
<para>
<literal>unaligned</> format writes all columns of a row on one
line, separated by the currently active field separator. This
is useful for creating output that might be intended to be read
in by other programs (for example, tab-separated or comma-separated
format).
</para>
<para>
<literal>aligned</literal> format is the standard, human-readable,
nicely formatted text output; this is the default.
</para>
<para>
<literal>wrapped</> format is like <literal>aligned</> but wraps
wide data values across lines to make the output fit in the target
column width. The target width is determined as described under
the <literal>columns</> option. Note that <application>psql</> will
not attempt to wrap column header titles; therefore,
<literal>wrapped</> format behaves the same as <literal>aligned</>
if the total width needed for column headers exceeds the target.
</para>
<para>
The <literal>html</>, <literal>latex</>, and <literal>troff-ms</>
formats put out tables that are intended to
be included in documents using the respective mark-up
language. They are not complete documents! (This might not be
so dramatic in <acronym>HTML</acronym>, but in LaTeX you must
have a complete document wrapper.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>columns</literal></term>
<listitem>
<para>
Sets the target width for the <literal>wrapped</> format, and also
the width limit for determining whether output is wide enough to
require the pager.
Zero (the default) causes the target width to be controlled by the
environment variable <envar>COLUMNS</>, or the detected screen width
if <envar>COLUMNS</> is not set.
In addition, if <literal>columns</> is zero then the
<literal>wrapped</> format only affects screen output.
If <literal>columns</> is nonzero then file and pipe output is
wrapped to that width as well.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>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 this depends on the particular format. In
<acronym>HTML</acronym> format, this will translate directly
into the <literal>border=...</literal> attribute; in the
other formats only values 0 (no border), 1 (internal dividing lines),
and 2 (table frame) make sense.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>linestyle</literal></term>
<listitem>
<para>
Sets the border line drawing style to one
of <literal>ascii</literal>, <literal>old-ascii</literal>
or <literal>unicode</literal>.
Unique abbreviations are allowed. (That would mean one
letter is enough.)
The default setting is <literal>ascii</>.
This option only affects the <literal>aligned</> and
<literal>wrapped</> output formats.
</para>
<para>
<literal>ascii</literal> style uses plain <acronym>ASCII</acronym>
characters. Newlines in data are shown using
a <literal>+</literal> symbol in the right-hand margin.
When the <literal>wrapped</literal> format wraps data from
one line to the next without a newline character, a dot
(<literal>.</>) is shown in the right-hand margin of the first line,
and again in the left-hand margin of the following line.
</para>
<para>
<literal>old-ascii</literal> style uses plain <acronym>ASCII</>
characters, using the formatting style used
in <productname>PostgreSQL</productname> 8.4 and earlier.
Newlines in data are shown using a <literal>:</literal>
symbol in place of the left-hand column separator.
When the data is wrapped from one line
to the next without a newline character, a <literal>;</>
symbol is used in place of the left-hand column separator.
</para>
<para>
<literal>unicode</literal> style uses Unicode box-drawing characters.
Newlines in data are shown using a carriage return symbol
in the right-hand margin. When the data is wrapped from one line
to the next without a newline character, an ellipsis symbol
is shown in the right-hand margin of the first line, and
again in the left-hand margin of the following line.
</para>
<para>
When the <literal>border</> setting is greater than zero,
this 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>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. If <replaceable
class="parameter">value</replaceable> is omitted the command toggles
between regular and expanded mode.
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.
</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>fieldsep</literal></term>
<listitem>
<para>
Specifies the field separator to be used in unaligned output
format. That way one can create, for example, tab- or
comma-separated output, which other programs might prefer. To
set a tab as field separator, type <literal>\pset fieldsep
'\t'</literal>. The default field separator is
<literal>'|'</literal> (a vertical bar).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>footer</literal></term>
<listitem>
<para>
If <replaceable class="parameter">value</replaceable> is specified
it must be either <literal>on</literal> or <literal>off</literal>
which will enable or disable display of the table footer
(the <literal>(<replaceable>n</> rows)</literal> count).
If <replaceable class="parameter">value</replaceable> is omitted the
command toggles footer display on or off.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>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>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>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>title</literal></term>
<listitem>
<para>
Sets the table title for any subsequently printed tables. This
can be used to give your output descriptive tags. If no
<replaceable class="parameter">value</replaceable> is given,
the title is unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>tableattr</literal> (or <literal>T</literal>)</term>
<listitem>
<para>
Specifies attributes to be placed inside the
<acronym>HTML</acronym> <sgmltag>table</sgmltag> tag in
<literal>html</> output format. 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>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>pager</literal></term>
<listitem>
<para>
Controls use of a pager program for query and <application>psql</>
help output. If the environment variable <envar>PAGER</envar>
is set, the output is piped to the specified program.
Otherwise a platform-dependent default (such as
<filename>more</filename>) is used.
</para>
<para>
When the <literal>pager</> option is <literal>off</>, the pager
program is not used. When the <literal>pager</> option is
<literal>on</>, the pager is used when appropriate, i.e., when the
output is to a terminal and will not fit on the screen.
The <literal>pager</> option can also be set to <literal>always</>,
which causes the pager to be used for all terminal output regardless
of whether it fits on the screen. <literal>\pset pager</>
without a <replaceable class="parameter">value</replaceable>
toggles pager use on and off.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
Illustrations of how these different formats look can be seen in
the <xref linkend="APP-PSQL-examples"
endterm="APP-PSQL-examples-title"> section.
</para>
<tip>
<para>
There are various shortcut commands for <command>\pset</command>. See
<command>\a</command>, <command>\C</command>, <command>\H</command>,
<command>\t</command>, <command>\T</command>, and <command>\x</command>.
</para>
</tip>
<note>
<para>
It is an error to call <command>\pset</command> without any
arguments. In the future this case might show the current status
of all printing options.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\q</literal></term>
<listitem>
<para>
Quits the <application>psql</application> program.
</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></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 or save the 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. This option is only available
if <application>psql</application> is configured to use the
<acronym>GNU</acronym> <application>Readline</application> library.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\set [ <replaceable class="parameter">name</replaceable> [ <replaceable class="parameter">value</replaceable> [ ... ] ] ]</literal></term>
<listitem>
<para>
Sets the internal 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 no second
argument is given, the variable is just set with no value. To
unset a variable, use the <command>\unset</command> command.
</para>
<para>
Valid variable names can contain characters, digits, and
underscores. See the section <xref
linkend="APP-PSQL-variables"
endterm="APP-PSQL-variables-title"> below for details.
Variable names are case-sensitive.
</para>
<para>
Although you are welcome to set any variable to anything you
want, <application>psql</application> treats several variables
as special. They are documented in the section about variables.
</para>
<note>
<para>
This command is totally separate from the <acronym>SQL</acronym>
command <xref linkend="SQL-SET" endterm="SQL-SET-title">.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\sf[+] <replaceable class="parameter">function_description</> </literal></term>
<listitem>
<para>
This command fetches and shows the definition of the named function,
in the form of a <command>CREATE OR REPLACE FUNCTION</> command.
The definition is printed to the current query output channel,
as set by <command>\o</command>.
</para>
<para>
The target function can be specified by name alone, or by name
and arguments, for example <literal>foo(integer, text)</>.
The argument types must be given if there is more
than one function of the same name.
</para>
<para>
If <literal>+</literal> is appended to the command name, then the
output lines are numbered, with the first line of the function body
being line 1.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\t</literal></term>
<listitem>
<para>
Toggles the display of output column name headings and row count
footer. This command is equivalent to <literal>\pset
tuples_only</literal> and is provided for convenience.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\T <replaceable class="parameter">table_options</replaceable></literal></term>
<listitem>
<para>
Specifies attributes to be placed within the
<sgmltag>table</sgmltag> tag in <acronym>HTML</acronym>
output format. This command is equivalent to <literal>\pset
tableattr <replaceable
class="parameter">table_options</replaceable></literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\timing [ <replaceable class="parameter">on</replaceable> | <replaceable class="parameter">off</replaceable> ]</literal></term>
<listitem>
<para>
Without parameter, toggles a display of how long each SQL statement
takes, in milliseconds. With parameter, sets same.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\w</literal> <replaceable class="parameter">filename</replaceable></term>
<term><literal>\w</literal> <literal>|</><replaceable class="parameter">command</replaceable></term>
<listitem>
<para>
Outputs the current query buffer to the file <replaceable
class="parameter">filename</replaceable> or pipes it to the Unix
command <replaceable class="parameter">command</replaceable>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\x</literal></term>
<listitem>
<para>
Toggles expanded table formatting mode. As such it is equivalent to
<literal>\pset expanded</literal>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\z [ <link linkend="APP-PSQL-patterns"><replaceable class="parameter">pattern</replaceable></link> ]</literal></term>
<listitem>
<para>
Lists tables, views and sequences with their
associated access privileges.
If a <replaceable class="parameter">pattern</replaceable> is
specified, only tables, views and sequences whose names match the
pattern are listed.
</para>
<para>
This is an alias for <command>\dp</command> (<quote>display
privileges</quote>).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\! [ <replaceable class="parameter">command</replaceable> ]</literal></term>
<listitem>
<para>
Escapes to a separate Unix shell or executes the Unix command
<replaceable class="parameter">command</replaceable>. The
arguments are not further interpreted; the shell will see them
as-is.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>\?</literal></term>
<listitem>
<para>
Shows help information about the backslash commands.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<refsect3 id="APP-PSQL-patterns">
<title id="APP-PSQL-patterns-title">Patterns</title>
<indexterm>
<primary>patterns</primary>
<secondary>in psql and pg_dump</secondary>
</indexterm>
<para>
The various <literal>\d</> commands accept a <replaceable
class="parameter">pattern</replaceable> parameter to specify the
object name(s) to be displayed. In the simplest case, a pattern
is just the exact name of the object. The characters within a
pattern are normally folded to lower case, just as in SQL names;
for example, <literal>\dt FOO</> will display the table named
<literal>foo</>. As in SQL names, placing double quotes around
a pattern stops folding to lower case. Should you need to include
an actual double quote character in a pattern, write it as a pair
of double quotes within a double-quote sequence; again this is in
accord with the rules for SQL quoted identifiers. For example,
<literal>\dt "FOO""BAR"</> will display the table named
<literal>FOO"BAR</> (not <literal>foo"bar</>). Unlike the normal
rules for SQL names, you can put double quotes around just part
of a pattern, for instance <literal>\dt FOO"FOO"BAR</> will display
the table named <literal>fooFOObar</>.
</para>
<para>
Whenever the <replaceable class="parameter">pattern</replaceable> parameter
is omitted completely, the <literal>\d</> commands display all objects
that are visible in the current schema search path &mdash; this is
equivalent to using <literal>*</> as the pattern.
(An object is said to be <firstterm>visible</> if its
containing schema is in the search path and no object of the same
kind and name appears earlier in the search path. This is equivalent to the
statement that the object can be referenced by name without explicit
schema qualification.)
To see all objects in the database regardless of visibility,
use <literal>*.*</> as the pattern.
</para>
<para>
Within a pattern, <literal>*</> matches any sequence of characters
(including no characters) and <literal>?</> matches any single character.
(This notation is comparable to Unix shell file name patterns.)
For example, <literal>\dt int*</> displays tables whose names
begin with <literal>int</>. But within double quotes, <literal>*</>
and <literal>?</> lose these special meanings and are just matched
literally.
</para>
<para>
A pattern that contains a dot (<literal>.</>) is interpreted as a schema
name pattern followed by an object name pattern. For example,
<literal>\dt foo*.*bar*</> displays all tables whose table name
includes <literal>bar</> that are in schemas whose schema name
starts with <literal>foo</>. When no dot appears, then the pattern
matches only objects that are visible in the current schema search path.
Again, a dot within double quotes loses its special meaning and is matched
literally.
</para>
<para>
Advanced users can use regular-expression notations such as character
classes, for example <literal>[0-9]</> to match any digit. All regular
expression special characters work as specified in
<xref linkend="functions-posix-regexp">, except for <literal>.</> which
is taken as a separator as mentioned above, <literal>*</> which is
translated to the regular-expression notation <literal>.*</>,
<literal>?</> which is translated to <literal>.</>, and
<literal>$</> which is matched literally. You can emulate
these pattern characters at need by writing
<literal>?</> for <literal>.</>,
<literal>(<replaceable class="parameter">R</replaceable>+|)</literal> for
<literal><replaceable class="parameter">R</replaceable>*</literal>, or
<literal>(<replaceable class="parameter">R</replaceable>|)</literal> for
<literal><replaceable class="parameter">R</replaceable>?</literal>.
<literal>$</> is not needed as a regular-expression character since
the pattern must match the whole name, unlike the usual
interpretation of regular expressions (in other words, <literal>$</>
is automatically appended to your pattern). Write <literal>*</> at the
beginning and/or end if you don't wish the pattern to be anchored.
Note that within double quotes, all regular expression special characters
lose their special meanings and are matched literally. Also, the regular
expression special characters are matched literally in operator name
patterns (i.e., the argument of <literal>\do</>).
</para>
</refsect3>
</refsect2>
<refsect2>
<title>Advanced features</title>
<refsect3 id="APP-PSQL-variables">
<title id="APP-PSQL-variables-title">Variables</title>
<para>
<application>psql</application> provides variable substitution
features similar to common Unix command shells.
Variables are simply name/value pairs, where the value
can be any string of any length. To set variables, use the
<application>psql</application> meta-command
<command>\set</command>:
<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 and use it as the argument of any slash
command:
<programlisting>
testdb=&gt; <userinput>\echo :foo</userinput>
bar
</programlisting>
</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>
If you call <command>\set</command> without a second argument, the
variable is set, with an empty string as value. To unset (or delete) a
variable, use the command <command>\unset</command>.
</para>
<para>
<application>psql</application>'s internal variable names can
consist of letters, numbers, and underscores in any order and any
number of them. A number of these variables are treated specially
by <application>psql</application>. They indicate certain option
settings that can be changed at run time by altering the value of
the variable or that represent some state of the application. Although
you can use these variables for any other purpose, this is not
recommended, as the program behavior might grow really strange
really quickly. By convention, all specially treated variables
consist of all upper-case letters (and possibly numbers and
underscores). To ensure maximum compatibility in the future, avoid
using such variable names for your own purposes. A list of all specially
treated variables follows.
</para>
<variablelist>
<varlistentry>
<indexterm>
<primary>autocommit</primary>
<secondary>psql</secondary>
</indexterm>
<term><varname>AUTOCOMMIT</varname></term>
<listitem>
<para>
When <literal>on</> (the default), each SQL command is automatically
committed upon successful completion. To postpone commit in this
mode, you must enter a <command>BEGIN</> or <command>START
TRANSACTION</> SQL command. When <literal>off</> or unset, SQL
commands are not committed until you explicitly issue
<command>COMMIT</> or <command>END</>. The autocommit-off
mode works by issuing an implicit <command>BEGIN</> for you, just
before any command that is not already in a transaction block and
is not itself a <command>BEGIN</> or other transaction-control
command, nor a command that cannot be executed inside a transaction
block (such as <command>VACUUM</>).
</para>
<note>
<para>
In autocommit-off mode, you must explicitly abandon any failed
transaction by entering <command>ABORT</> or <command>ROLLBACK</>.
Also keep in mind that if you exit the session
without committing, your work will be lost.
</para>
</note>
<note>
<para>
The autocommit-on mode is <productname>PostgreSQL</>'s traditional
behavior, but autocommit-off is closer to the SQL spec. If you
prefer autocommit-off, you might wish to set it in the system-wide
<filename>psqlrc</filename> file or your
<filename>~/.psqlrc</filename> file.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>DBNAME</varname></term>
<listitem>
<para>
The name of the database you are currently connected to. This is
set every time you connect to a database (including program
start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ECHO</varname></term>
<listitem>
<para>
If set to <literal>all</literal>, all lines
entered from the keyboard or from a script are written to the standard output
before they are parsed or executed. To select this behavior on program
start-up, use the switch <option>-a</option>. If set to
<literal>queries</literal>,
<application>psql</application> merely prints all queries as
they are sent to the server. The switch for this is
<option>-e</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ECHO_HIDDEN</varname></term>
<listitem>
<para>
When this variable is set and a backslash command queries the
database, the query is first shown. This way you can study the
<productname>PostgreSQL</productname> internals and provide
similar functionality in your own programs. (To select this behavior
on program start-up, use the switch <option>-E</option>.) If you set
the variable to the value <literal>noexec</literal>, the queries are
just shown but are not actually sent to the server and executed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ENCODING</varname></term>
<listitem>
<para>
The current client character set encoding.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>FETCH_COUNT</varname></term>
<listitem>
<para>
If this variable is set to an integer value &gt; 0,
the results of <command>SELECT</command> queries are fetched
and displayed in groups of that many rows, rather than the
default behavior of collecting the entire result set before
display. Therefore only a
limited amount of memory is used, regardless of the size of
the result set. Settings of 100 to 1000 are commonly used
when enabling this feature.
Keep in mind that when using this feature, a query might
fail after having already displayed some rows.
</para>
<tip>
<para>
Although you can use any output format with this feature,
the default <literal>aligned</> format tends to look bad
because each group of <varname>FETCH_COUNT</varname> rows
will be formatted separately, leading to varying column
widths across the row groups. The other output formats work better.
</para>
</tip>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HISTCONTROL</varname></term>
<listitem>
<para>
If this variable is set to <literal>ignorespace</literal>,
lines which begin with a space are not entered into the history
list. If set to a value of <literal>ignoredups</literal>, lines
matching the previous history line are not entered. A value of
<literal>ignoreboth</literal> combines the two options. If
unset, or if set to any other value than those above, all lines
read in interactive mode are saved on the history list.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HISTFILE</varname></term>
<listitem>
<para>
The file name that will be used to store the history list. The default
value is <filename>~/.psql_history</filename>. For example, putting:
<programlisting>
\set HISTFILE ~/.psql_history- :DBNAME
</programlisting>
in <filename>~/.psqlrc</filename> will cause
<application>psql</application> to maintain a separate history for
each database.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HISTSIZE</varname></term>
<listitem>
<para>
The number of commands to store in the command history. The
default value is 500.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>HOST</varname></term>
<listitem>
<para>
The database server host you are currently connected to. This is
set every time you connect to a database (including program
start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>IGNOREEOF</varname></term>
<listitem>
<para>
If unset, sending an <acronym>EOF</> character (usually
<keycombo action="simul"><keycap>Control</><keycap>D</></>)
to an interactive session of <application>psql</application>
will terminate the application. If set to a numeric value,
that many <acronym>EOF</> characters are ignored before the
application terminates. If the variable is set but has no
numeric value, the default is 10.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>Bash</application>.
</para>
</note>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>LASTOID</varname></term>
<listitem>
<para>
The value of the last affected OID, as returned from an
<command>INSERT</command> or <command>lo_insert</command>
command. This variable is only guaranteed to be valid until
after the result of the next <acronym>SQL</acronym> command has
been displayed.
</para>
</listitem>
</varlistentry>
<varlistentry>
<indexterm>
<primary>rollback</primary>
<secondary>psql</secondary>
</indexterm>
<term><varname>ON_ERROR_ROLLBACK</varname></term>
<listitem>
<para>
When <literal>on</>, if a statement in a transaction block
generates an error, the error is ignored and the transaction
continues. When <literal>interactive</>, such errors are only
ignored in interactive sessions, and not when reading script
files. When <literal>off</> (the default), a statement in a
transaction block that generates an error aborts the entire
transaction. The on_error_rollback-on mode works by issuing an
implicit <command>SAVEPOINT</> for you, just before each command
that is in a transaction block, and rolls back to the savepoint
on error.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>ON_ERROR_STOP</varname></term>
<listitem>
<para>
By default, if non-interactive scripts encounter an error, such
as a malformed <acronym>SQL</acronym> command or internal
meta-command, processing continues. This has been the
traditional behavior of <application>psql</application> but it
is sometimes not desirable. If this variable is set, script
processing will immediately terminate. If the script was called
from another script it will terminate in the same fashion. If
the outermost script was not called from an interactive
<application>psql</application> session but rather using the
<option>-f</option> option, <application>psql</application> will
return error code 3, to distinguish this case from fatal error
conditions (error code 1).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>PORT</varname></term>
<listitem>
<para>
The database server port to which you are currently connected.
This is set every time you connect to a database (including
program start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>PROMPT1</varname></term>
<term><varname>PROMPT2</varname></term>
<term><varname>PROMPT3</varname></term>
<listitem>
<para>
These specify what the prompts <application>psql</application>
issues should look like. See <xref
linkend="APP-PSQL-prompting"
endterm="APP-PSQL-prompting-title"> below.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>QUIET</varname></term>
<listitem>
<para>
This variable is equivalent to the command line option
<option>-q</option>. It is probably not too useful in
interactive mode.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SINGLELINE</varname></term>
<listitem>
<para>
This variable is equivalent to the command line option
<option>-S</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>SINGLESTEP</varname></term>
<listitem>
<para>
This variable is equivalent to the command line option
<option>-s</option>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>USER</varname></term>
<listitem>
<para>
The database user you are currently connected as. This is set
every time you connect to a database (including program
start-up), but can be unset.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><varname>VERBOSITY</varname></term>
<listitem>
<para>
This variable can be set to the values <literal>default</>,
<literal>verbose</>, or <literal>terse</> to control the verbosity
of error reports.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect3>
<refsect3>
<title><acronym>SQL</acronym> Interpolation</title>
<para>
An additional useful feature of <application>psql</application>
variables is that you can substitute (<quote>interpolate</quote>)
them into regular <acronym>SQL</acronym> statements.
<application>psql</application> provides special facilities for
ensuring that values used as SQL literals and identifiers are
properly escaped. The syntax for interpolating a value without
any special escaping is again to prepend the variable name with a colon
(<literal>:</literal>):
<programlisting>
testdb=&gt; <userinput>\set foo 'my_table'</userinput>
testdb=&gt; <userinput>SELECT * FROM :foo;</userinput>
</programlisting>
would then query the table <literal>my_table</literal>. Note that this
may be unsafe: the value of the variable is copied literally, so it can
even contain unbalanced quotes or 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 escaped. To escape the value of
a variable as an SQL literal, write a colon followed by the variable
name in single quotes. To escape the value an SQL identifier, write
a colon followed by the variable name in double quotes. 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>
Variable interpolation will not be performed into quoted
<acronym>SQL</acronym> entities.
</para>
<para>
One possible 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 proceed as above:
<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.
psql does not support embedded NUL bytes in variable values.)
</para>
<para>
Since colons can legally appear in SQL commands, an apparent attempt
at interpolation (such as <literal>:name</literal>,
<literal>:'name'</literal>, or <literal>:"name"</literal>) is not
changed unless the named variable is currently set. In any case, you
can escape a colon with a backslash to protect it from substitution.
(The colon syntax for variables is standard <acronym>SQL</acronym> for
embedded query languages, such as <application>ECPG</application>.
The colon syntax for array slices and type casts are
<productname>PostgreSQL</productname> extensions, hence the
conflict. The colon syntax for escaping a variable's value as an
SQL literal or identifier is a <application>psql</application>
extension.)
</para>
</refsect3>
<refsect3 id="APP-PSQL-prompting">
<title id="APP-PSQL-prompting-title">Prompting</title>
<para>
The prompts <application>psql</application> issues can be customized
to your preference. The three variables <varname>PROMPT1</varname>,
<varname>PROMPT2</varname>, and <varname>PROMPT3</varname> contain strings
and special escape sequences that describe the appearance of the
prompt. Prompt 1 is the normal prompt that is issued when
<application>psql</application> requests a new command. Prompt 2 is
issued when more input is expected during command input because the
command was not terminated with a semicolon or a quote was not closed.
Prompt 3 is issued when you run an <acronym>SQL</acronym>
<command>COPY</command> command and you are expected to type in the
row values on the terminal.
</para>
<para>
The value of the selected prompt variable is printed literally,
except where a percent sign (<literal>%</literal>) is encountered.
Depending on the next character, certain other text is substituted
instead. Defined substitutions are:
<variablelist>
<varlistentry>
<term><literal>%M</literal></term>
<listitem>
<para>
The full host name (with domain name) of the database server,
or <literal>[local]</literal> if the connection is over a Unix
domain socket, or
<literal>[local:<replaceable>/dir/name</replaceable>]</literal>,
if the Unix domain socket is not at the compiled in default
location.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%m</literal></term>
<listitem>
<para>
The host name of the database server, truncated at the
first dot, or <literal>[local]</literal> if the connection is
over a Unix domain socket.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%&gt;</literal></term>
<listitem><para>The port number at which the database server is listening.</para></listitem>
</varlistentry>
<varlistentry>
<term><literal>%n</literal></term>
<listitem>
<para>
The database session user name. (The expansion of this
value might change during a database session as the result
of the command <command>SET SESSION
AUTHORIZATION</command>.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%/</literal></term>
<listitem><para>The name of the current database.</para></listitem>
</varlistentry>
<varlistentry>
<term><literal>%~</literal></term>
<listitem><para>Like <literal>%/</literal>, but the output is <literal>~</literal>
(tilde) if the database is your default database.</para></listitem>
</varlistentry>
<varlistentry>
<term><literal>%#</literal></term>
<listitem>
<para>
If the session user is a database superuser, then a
<literal>#</literal>, otherwise a <literal>&gt;</literal>.
(The expansion of this value might change during a database
session as the result of the command <command>SET SESSION
AUTHORIZATION</command>.)
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%R</literal></term>
<listitem>
<para>
In prompt 1 normally <literal>=</literal>, but <literal>^</literal> if
in single-line mode, and <literal>!</literal> if the session is
disconnected from the database (which can happen if
<command>\connect</command> fails). In prompt 2 the sequence is
replaced by <literal>-</literal>, <literal>*</literal>, a single quote,
a double quote, or a dollar sign, depending on whether
<application>psql</application> expects more input because the
command wasn't terminated yet, because you are inside a
<literal>/* ... */</literal> comment, or because you are inside
a quoted or dollar-escaped string. In prompt 3 the sequence doesn't
produce anything.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%x</literal></term>
<listitem>
<para>
Transaction status: an empty string when not in a transaction
block, or <literal>*</> when in a transaction block, or
<literal>!</> when in a failed transaction block, or <literal>?</>
when the transaction state is indeterminate (for example, because
there is no connection).
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%</literal><replaceable class="parameter">digits</replaceable></term>
<listitem>
<para>
The character with the indicated octal code is substituted.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%:</literal><replaceable class="parameter">name</replaceable><literal>:</literal></term>
<listitem>
<para>
The value of the <application>psql</application> variable
<replaceable class="parameter">name</replaceable>. See the
section <xref linkend="APP-PSQL-variables"
endterm="APP-PSQL-variables-title"> for details.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%`</literal><replaceable class="parameter">command</replaceable><literal>`</literal></term>
<listitem>
<para>
The output of <replaceable
class="parameter">command</replaceable>, similar to ordinary
<quote>back-tick</quote> substitution.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><literal>%[</literal> ... <literal>%]</literal></term>
<listitem>
<para>
Prompts can contain terminal control characters which, for
example, change the color, background, or style of the prompt
text, or change the title of the terminal window. In order for
the line editing features of <application>Readline</application> to work properly, these
non-printing control characters must be designated as invisible
by surrounding them with <literal>%[</literal> and
<literal>%]</literal>. Multiple pairs of these can occur within
the prompt. For example:
<programlisting>
testdb=&gt; \set PROMPT1 '%[%033[1;33;40m%]%n@%/%R%[%033[0m%]%# '
</programlisting>
results in a boldfaced (<literal>1;</literal>) yellow-on-black
(<literal>33;40</literal>) prompt on VT100-compatible, color-capable
terminals.
</para>
</listitem>
</varlistentry>
</variablelist>
To insert a percent sign into your prompt, write
<literal>%%</literal>. The default prompts are
<literal>'%/%R%# '</literal> for prompts 1 and 2, and
<literal>'&gt;&gt; '</literal> for prompt 3.
</para>
<note>
<para>
This feature was shamelessly plagiarized from
<application>tcsh</application>.
</para>
</note>
</refsect3>
<refsect3>
<title>Command-Line Editing</title>