PSQL(1) PostgreSQL Client Applications PSQL(1)NAMEpsql - PostgreSQL interactive terminal
SYNOPSISpsql [ option... ] [ dbname
[ username ] ]
DESCRIPTIONpsql is a terminal-based front-end to PostgreSQL. It enables you to
type in queries interactively, issue them to PostgreSQL, 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.
OPTIONS-a
--echo-all
Print all input lines to standard output as they are read. This
is more useful for script processing rather than interactive
mode. This is equivalent to setting the variable ECHO to all.
-A
--no-align
Switches to unaligned output mode. (The default output mode is
otherwise aligned.)
-c command
--command command
Specifies that psql is to execute one command string, command,
and then exit. This is useful in shell scripts.
command must be either a command string that is completely
parsable by the server (i.e., it contains no psql specific fea‐
tures), or a single backslash command. Thus you cannot mix SQL
and psql meta-commands. To achieve that, you could pipe the
string into psql, like this: echo "\x \\ select * from foo;" |
psql.
If the command string contains multiple SQL commands, they are
processed in a single transaction, unless there are explicit
BEGIN/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 psql's standard input.
-d dbname
--dbname dbname
Specifies the name of the database to connect to. This is equiv‐
alent to specifying dbname as the first non-option argument on
the command line.
-e
--echo-queries
Copy all SQL commands sent to the server to standard output as
well. This is equivalent to setting the variable ECHO to
queries.
-E
--echo-hidden
Echo the actual queries generated by \d and other backslash com‐
mands. You can use this to study psql's internal operations.
This is equivalent to setting the variable ECHO_HIDDEN from
within psql.
-f filename
--file filename
Use the file filename as the source of commands instead of read‐
ing commands interactively. After the file is processed, psql
terminates. This is in many ways equivalent to the internal com‐
mand \i.
If filename is - (hyphen), then standard input is read.
Using this option is subtly different from writing psql < file‐
name. In general, both will do what you expect, but using -f
enables some nice features such as error messages with line num‐
bers. 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 that you would have gotten had you
entered everything by hand.
-F separator
--field-separator separator
Use separator as the field separator for unaligned output. This
is equivalent to \pset fieldsep or \f.
-h hostname
--host hostname
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.
-H
--html Turn on HTML tabular output. This is equivalent to \pset format
html or the \H command.
-l
--list List all available databases, then exit. Other non-connection
options are ignored. This is similar to the internal command
\list.
-L filename
--log-file filename
Write all query output into file filename, in addition to the
normal output destination.
-o filename
--output filename
Put all query output into file filename. This is equivalent to
the command \o.
-p port
--port port
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 PGPORT environment variable or, if
not set, to the port specified at compile time, usually 5432.
-P assignment
--pset assignment
Allows you to specify printing options in the style of \pset on
the command line. Note that here you have to separate name and
value with an equal sign instead of a space. Thus to set the
output format to LaTeX, you could write -P format=latex.
-q
--quiet
Specifies that psql 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 -c option. Within psql you can also set the QUIET variable
to achieve the same effect.
-R separator
--record-separator separator
Use separator as the record separator for unaligned output. This
is equivalent to the \pset recordsep command.
-s
--single-step
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.
-S
--single-line
Runs in single-line mode where a newline terminates an SQL com‐
mand, as a semicolon does.
Note: This mode is provided for those who insist on it, but you
are not necessarily encouraged to use it. In particular, if you
mix SQL and meta-commands on a line the order of execution might
not always be clear to the inexperienced user.
-t
--tuples-only
Turn off printing of column names and result row count footers,
etc. This is equivalent to the \t command.
-T table_options
--table-attr table_options
Allows you to specify options to be placed within the HTML table
tag. See \pset for details.
-u Forces psql to prompt for the user name and password before con‐
necting to the database.
This option is deprecated, as it is conceptually flawed.
(Prompting for a non-default user name and prompting for a pass‐
word because the server requires it are really two different
things.) You are encouraged to look at the -U and -W options
instead.
-U username
--username username
Connect to the database as the user username instead of the
default. (You must have permission to do so, of course.)
-v assignment
--set assignment
--variable assignment
Perform a variable assignment, like the \set 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.
-V
--version
Print the psql version and exit.
-W
--password
Forces psql to prompt for a password before connecting to a
database.
psql should automatically prompt for a password whenever the
server requests password authentication. However, currently
password request detection is not totally reliable, hence this
option to force a prompt. If no password prompt is issued and
the server requires password authentication, the connection
attempt will fail.
This option will remain set for the entire session, even if you
change the database connection with the meta-command \connect.
-x
--expanded
Turn on the expanded table formatting mode. This is equivalent
to the \x command.
-X,
--no-psqlrc
Do not read the start-up file (neither the system-wide psqlrc
file nor the user's ~/.psqlrc file).
-?
--help Show help about psql command line arguments, and exit.
EXIT STATUSpsql returns 0 to the shell if it finished normally, 1 if a fatal error
of its own (out of memory, file not found) occurs, 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 ON_ERROR_STOP was set.
USAGE
CONNECTING TO A DATABASE
psql is a regular PostgreSQL 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 con‐
nect as. psql can be told about those parameters via command line
options, namely -d, -h, -p, and -U 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 these options are required; there are useful defaults.
If you omit the host name, psql will connect via a Unix-domain socket
to a server on the local host, or via TCP/IP to localhost on machines
that don't have Unix-domain sockets. The default port number is deter‐
mined 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 can't just connect to any database under any user
name. Your database administrator should have informed you about your
access rights.
When the defaults aren't quite right, you can save yourself some typing
by setting the environment variables PGDATABASE, PGHOST, PGPORT and/or
PGUSER to appropriate values. (For additional environment variables,
see the documentation.) It is also convenient to have a ~/.pgpass file
to avoid regularly having to type in passwords. See the documentation
for more information.
If the connection could not be made for any reason (e.g., insufficient
privileges, server is not running on the targeted host, etc.), psql
will return an error and terminate.
ENTERING SQL COMMANDS
In normal operation, psql provides a prompt with the name of the data‐
base to which psql is currently connected, followed by the string =>.
For example,
$ psql testdb
Welcome to psql 8.1.0, the PostgreSQL interactive terminal.
Type: \copyright for distribution terms
\h for help with SQL commands
\? for help with psql commands
\g or terminate with semicolon to execute query
\q to quit
testdb=>
At the prompt, the user may type in SQL 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.
Whenever a command is executed, psql also polls for asynchronous noti‐
fication events generated by LISTEN [listen(7)] and NOTIFY [notify(7)].
META-COMMANDS
Anything you enter in psql that begins with an unquoted backslash is a
psql meta-command that is processed by psql itself. These commands help
make psql more useful for administration or scripting. Meta-commands
are more commonly called slash or backslash commands.
The format of a psql 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.
To include whitespace into an argument you may quote it with a single
quote. To include a single quote into such an argument, precede it by a
backslash. Anything contained in single quotes is furthermore subject
to C-like substitutions for \n (new line), \t (tab), \digits (octal),
and \xdigits (hexadecimal).
If an unquoted argument begins with a colon (:), it is taken as a psql
variable and the value of the variable is used as the argument instead.
Arguments that are enclosed in backquotes (`) 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.
Some commands take an SQL identifier (such as a table name) as argu‐
ment. These arguments follow the syntax rules of SQL: Unquoted letters
are forced to lowercase, while double quotes (") protect letters from
case conversion and allow incorporation of whitespace into the identi‐
fier. Within double quotes, paired double quotes reduce to a single
double quote in the resulting name. For example, FOO"BAR"BAZ is inter‐
preted as fooBARbaz, and "A weird"" name" becomes A weird" name.
Parsing for arguments stops when another unquoted backslash occurs.
This is taken as the beginning of a new meta-command. The special
sequence \\ (two backslashes) marks the end of arguments and continues
parsing SQL commands, if any. That way SQL and psql commands can be
freely mixed on a line. But in any case, the arguments of a meta-com‐
mand cannot continue beyond the end of the line.
The following meta-commands are defined:
\a 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 \pset for
a more general solution.
\cd [ directory ]
Changes the current working directory to directory. Without
argument, changes to the current user's home directory.
Tip: To print your current working directory, use \!pwd.
\C [ title ]
Sets the title of any tables being printed as the result of a
query or unset any such title. This command is equivalent to
\pset title title. (The name of this command derives from ``cap‐
tion'', as it was previously only used to set the caption in an
HTML table.)
\connect (or \c) [ dbname [ username ] ]
Establishes a connection to a new database and/or under a user
name. The previous connection is closed. If dbname is - the cur‐
rent database name is assumed.
If username is omitted the current user name is assumed.
As a special rule, \connect without any arguments will connect
to the default database as the default user (as you would have
gotten by starting psql without any arguments).
If the connection attempt failed (wrong user name, access
denied, etc.), the previous connection will be kept if and only
if psql 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 acci‐
dentally acting on the wrong database on the other hand.
\copy table
Performs a frontend (client) copy. This is an operation that
runs an SQL COPY [copy(7)] command, but instead of the server
reading or writing the specified file, psql 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.
The syntax of the command is similar to that of the SQL COPY
[copy(7)] command. Note that, because of this, special parsing
rules apply to the \copy command. In particular, the variable
substitution rules and backslash escapes do not apply.
\copy table from stdin | stdout reads/writes based on the com‐
mand input and output respectively. All rows are read from the
same source that issued the command, continuing until \. is read
or the stream reaches EOF. Output is sent to the same place as
command output. To read/write from psql's standard input or out‐
put, use pstdin or pstdout. This option is useful for populating
tables in-line within a SQL script file.
Tip: This operation is not as efficient as the SQL COPY command
because all data must pass through the client/server connection.
For large amounts of data the SQL command may be preferable.
\copyright
Shows the copyright and distribution terms of PostgreSQL.
\d [ pattern ]
\d+ [ pattern ]
For each relation (table, view, index, or sequence) matching the
pattern, show all columns, their types, the tablespace (if not
the default) and any special attributes such as NOT NULL or
defaults, if any. Associated indexes, constraints, rules, and
triggers are also shown, as is the view definition if the rela‐
tion is a view. (``Matching the pattern'' is defined below.)
The command form \d+ 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.
Note: If \d is used without a pattern argument, it is equivalent
to \dtvs which will show a list of all tables, views, and
sequences. This is purely a convenience measure.
\da [ pattern ]
Lists all available aggregate functions, together with the data
type they operate on. If pattern is specified, only aggregates
whose names match the pattern are shown.
\db [ pattern ]
\db+ [ pattern ]
Lists all available tablespaces. If pattern is specified, only
tablespaces whose names match the pattern are shown. If + is
appended to the command name, each object is listed with its
associated permissions.
\dc [ pattern ]
Lists all available conversions between character-set encodings.
If pattern is specified, only conversions whose names match the
pattern are listed.
\dC Lists all available type casts.
\dd [ pattern ]
Shows the descriptions of objects matching the pattern, or of
all visible objects if no argument is given. But in either case,
only objects that have a description are listed. (``Object''
covers aggregates, functions, operators, types, relations
(tables, views, indexes, sequences, large objects), rules, and
triggers.) For example:
=> \dd version
Object descriptions
Schema | Name | Object | Description
------------+---------+----------+---------------------------
pg_catalog | version | function | PostgreSQL version string
(1 row)
Descriptions for objects can be created with the COMMENT [com‐
ment(7)] SQL command.
\dD [ pattern ]
Lists all available domains. If pattern is specified, only
matching domains are shown.
\df [ pattern ]
\df+ [ pattern ]
Lists available functions, together with their argument and
return types. If pattern is specified, only functions whose
names match the pattern are shown. If the form \df+ is used,
additional information about each function, including language
and description, is shown.
Note:
To look up functions taking argument or returning values of a
specific type, use your pager's search capability to scroll
through the \df output.
To reduce clutter, \df does not show data type I/O functions.
This is implemented by ignoring functions that accept or return
type cstring.
\dg [ pattern ]
Lists all database roles. If pattern is specified, only those
roles whose names match the pattern are listed. (This command
is now effectively the same as \du.)
\distvS [ pattern ]
This is not the actual command name: the letters i, s, t, v, S
stand for index, sequence, table, view, and system table,
respectively. You can specify any or all of these letters, in
any order, to obtain a listing of all the matching objects. The
letter S restricts the listing to system objects; without S,
only non-system objects are shown. If + is appended to the com‐
mand name, each object is listed with its associated descrip‐
tion, if any.
If pattern is specified, only objects whose names match the pat‐
tern are listed.
\dl This is an alias for \lo_list, which shows a list of large
objects.
\dn [ pattern ]
\dn+ [ pattern ]
Lists all available schemas (namespaces). If pattern (a regular
expression) is specified, only schemas whose names match the
pattern are listed. Non-local temporary schemas are suppressed.
If + is appended to the command name, each object is listed with
its associated permissions and description, if any.
\do [ pattern ]
Lists available operators with their operand and return types.
If pattern is specified, only operators whose names match the
pattern are listed.
\dp [ pattern ]
Produces a list of all available tables, views and sequences
with their associated access privileges. If pattern is speci‐
fied, only tables, views and sequences whose names match the
pattern are listed.
The commands GRANT and REVOKE are used to set access privileges.
See GRANT [grant(7)] for more information.
\dT [ pattern ]
\dT+ [ pattern ]
Lists all data types or only those that match pattern. The com‐
mand form \dT+ shows extra information.
\du [ pattern ]
Lists all database roles, or only those that match pattern.
\edit (or \e) [ filename ]
If filename is specified, the file is edited; after the editor
exits, its content is copied back to the query buffer. If no
argument is given, the current query buffer is copied to a tem‐
porary file which is then edited in the same fashion.
The new query buffer is then re-parsed according to the normal
rules of psql, where the whole buffer is treated as a single
line. (Thus you cannot make scripts this way. Use \i for that.)
This means also that if the query ends with (or rather contains)
a semicolon, it is immediately executed. In other cases it will
merely wait in the query buffer.
Tip: psql searches the environment variables PSQL_EDITOR, EDI‐
TOR, and VISUAL (in that order) for an editor to use. If all of
them are unset, vi is used on Unix systems, notepad.exe on Win‐
dows systems.
\echo text [ ... ]
Prints the arguments to the standard output, separated by one
space and followed by a newline. This can be useful to inter‐
sperse information in the output of scripts. For example:
=> \echo `date`
Tue Oct 26 21:40:57 CEST 1999
If the first argument is an unquoted -n the trailing newline is
not written.
Tip: If you use the \o command to redirect your query output you
may wish to use \qecho instead of this command.
\encoding [ encoding ]
Sets the client character set encoding. Without an argument,
this command shows the current encoding.
\f [ string ]
Sets the field separator for unaligned query output. The default
is the vertical bar (|). See also \pset for a generic way of
setting output options.
\g [ { filename | |command } ]
Sends the current query input buffer to the server and option‐
ally stores the query's output in filename or pipes the output
into a separate Unix shell executing command. A bare \g is vir‐
tually equivalent to a semicolon. A \g with argument is a ``one-
shot'' alternative to the \o command.
\help (or \h) [ command ]
Gives syntax help on the specified SQL command. If command is
not specified, then psql will list all the commands for which
syntax help is available. If command is an asterisk (*), then
syntax help on all SQL commands is shown.
Note: To simplify typing, commands that consists of several
words do not have to be quoted. Thus it is fine to type \help
alter table.
\H Turns on HTML query output format. If the HTML format is already
on, it is switched back to the default aligned text format. This
command is for compatibility and convenience, but see \pset
about setting other output options.
\i filename
Reads input from the file filename and executes it as though it
had been typed on the keyboard.
Note: If you want to see the lines on the screen as they are
read you must set the variable ECHO to all.
\l (or \list)
\l+ (or \list+)
List the names, owners, and character set encodings of all the
databases in the server. If + is appended to the command name,
database descriptions are also displayed.
\lo_export loid filename
Reads the large object with OID loid from the database and
writes it to filename. Note that this is subtly different from
the server function lo_export, which acts with the permissions
of the user that the database server runs as and on the server's
file system.
Tip: Use \lo_list to find out the large object's OID.
\lo_import filename [ comment ]
Stores the file into a PostgreSQL large object. Optionally, it
associates the given comment with the object. Example:
foo=> \lo_import '/home/peter/pictures/photo.xcf' 'a picture of me'
lo_import 152801
The response indicates that the large object received object ID
152801 which one ought to remember if one wants to access the
object ever again. For that reason it is recommended to always
associate a human-readable comment with every object. Those can
then be seen with the \lo_list command.
Note that this command is subtly different from the server-side
lo_import because it acts as the local user on the local file
system, rather than the server's user and file system.
\lo_list
Shows a list of all PostgreSQL large objects currently stored in
the database, along with any comments provided for them.
\lo_unlink loid
Deletes the large object with OID loid from the database.
Tip: Use \lo_list to find out the large object's OID.
\o [ {filename | |command} ]
Saves future query results to the file filename or pipes future
results into a separate Unix shell to execute command. If no
arguments are specified, the query output will be reset to the
standard output.
``Query results'' 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 \d),
but not error messages.
Tip: To intersperse text output in between query results, use
\qecho.
\p Print the current query buffer to the standard output.
\pset parameter [ value ]
This command sets options affecting the output of query result
tables. parameter describes which option is to be set. The
semantics of value depend thereon.
Adjustable printing options are:
format Sets the output format to one of unaligned, aligned,
html, latex, or troff-ms. Unique abbreviations are
allowed. (That would mean one letter is enough.)
``Unaligned'' writes all columns of a row on a line, sep‐
arated by the currently active field separator. This is
intended to create output that might be intended to be
read in by other programs (tab-separated, comma-sepa‐
rated). ``Aligned'' mode is the standard, human-read‐
able, nicely formatted text output that is default. The
``HTML'' and ``LaTeX'' modes 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 HTML, but in LaTeX you must
have a complete document wrapper.)
border The second argument 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
HTML mode, this will translate directly into the bor‐
der=... attribute, in the others only values 0 (no bor‐
der), 1 (internal dividing lines), and 2 (table frame)
make sense.
expanded (or x)
Toggles between regular and expanded format. When
expanded format 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 ``horizontal''
mode.
Expanded mode is supported by all four output formats.
null The second argument is a string that should be printed
whenever a column is null. The default is not to print
anything, which can easily be mistaken for, say, an empty
string. Thus, one might choose to write \pset null
'(null)'.
fieldsep
Specifies the field separator to be used in unaligned
output mode. 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 \pset
fieldsep '\t'. The default field separator is '|' (a ver‐
tical bar).
footer Toggles the display of the default footer (x rows).
numericlocale
Toggles the display of a locale-aware character to sepa‐
rate groups of digits to the left of the decimal marker.
It also enables a locale-aware decimal marker.
recordsep
Specifies the record (line) separator to use in unaligned
output mode. The default is a newline character.
tuples_only (or t)
Toggles between tuples only and full display. Full dis‐
play may show extra information such as column headers,
titles, and various footers. In tuples only mode, only
actual table data is shown.
title [ text ]
Sets the table title for any subsequently printed tables.
This can be used to give your output descriptive tags. If
no argument is given, the title is unset.
tableattr (or T) [ text ]
Allows you to specify any attributes to be placed inside
the HTML table tag. This could for example be cellpadding
or bgcolor. Note that you probably don't want to specify
border here, as that is already taken care of by \pset
border.
pager Controls use of a pager for query and psql help output.
If the environment variable PAGER is set, the output is
piped to the specified program. Otherwise a platform-
dependent default (such as more) is used.
When the pager is off, the pager is not used. When the
pager is on, the pager is used only when appropriate,
i.e. the output is to a terminal and will not fit on the
screen. (psql does not do a perfect job of estimating
when to use the pager.) \pset pager turns the pager on
and off. Pager can also be set to always, which causes
the pager to be always used.
Illustrations on how these different formats look can be seen in the
Examples [psql(1)] section.
Tip: There are various shortcut commands for \pset. See \a, \C,
\H, \t, \T, and \x.
Note: It is an error to call \pset without arguments. In the
future this call might show the current status of all printing
options.
\q Quits the psql program.
\qecho text [ ... ]
This command is identical to \echo except that the output will
be written to the query output channel, as set by \o.
\r Resets (clears) the query buffer.
\s [ filename ]
Print or save the command line history to filename. If filename
is omitted, the history is written to the standard output. This
option is only available if psql is configured to use the GNU
Readline library.
Note: In the current version, it is no longer necessary to save
the command history, since that will be done automatically on
program termination. The history is also loaded automatically
every time psql starts up.
\set [ name [ value [ ... ] ] ]
Sets the internal variable name to value or, if more than one
value is given, to the concatenation of all of them. If no sec‐
ond argument is given, the variable is just set with no value.
To unset a variable, use the \unset command.
Valid variable names can contain characters, digits, and under‐
scores. See the section Variables [psql(1)] below for details.
Variable names are case-sensitive.
Although you are welcome to set any variable to anything you
want, psql treats several variables as special. They are docu‐
mented in the section about variables.
Note: This command is totally separate from the SQL command SET
[set(7)].
\t Toggles the display of output column name headings and row count
footer. This command is equivalent to \pset tuples_only and is
provided for convenience.
\T table_options
Allows you to specify attributes to be placed within the table
tag in HTML tabular output mode. This command is equivalent to
\pset tableattr table_options.
\timing
Toggles a display of how long each SQL statement takes, in mil‐
liseconds.
\w {filename | |command}
Outputs the current query buffer to the file filename or pipes
it to the Unix command command.
\x Toggles expanded table formatting mode. As such it is equivalent
to \pset expanded.
\z [ pattern ]
Produces a list of all available tables, views and sequences
with their associated access privileges. If a pattern is speci‐
fied, only tables,views and sequences whose names match the pat‐
tern are listed.
The commands GRANT and REVOKE are used to set access privileges.
See GRANT [grant(7)] for more information.
This is an alias for \dp (``display privileges'').
\! [ command ]
Escapes to a separate Unix shell or executes the Unix command
command. The arguments are not further interpreted, the shell
will see them as is.
\? Shows help information about the backslash commands.
The various \d commands accept a pattern parameter to specify the
object name(s) to be displayed. * means ``any sequence of characters''
and ? means ``any single character''. (This notation is comparable to
Unix shell file name patterns.) Advanced users can also use regular-
expression notations such as character classes, for example [0-9] to
match ``any digit''. To make any of these pattern-matching characters
be interpreted literally, surround it with double quotes.
A pattern that contains an (unquoted) dot is interpreted as a schema
name pattern followed by an object name pattern. For example, \dt
foo*.bar* displays all tables in schemas whose name starts with foo and
whose table name starts with bar. If no dot appears, then the pattern
matches only objects that are visible in the current schema search
path.
Whenever the pattern parameter is omitted completely, the \d commands
display all objects that are visible in the current schema search path.
To see all objects in the database, use the pattern *.*.
ADVANCED FEATURES
VARIABLES
psql 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 psql meta-
command \set:
testdb=> \set foo bar
sets the variable foo to the value bar. To retrieve the content of the
variable, precede the name with a colon and use it as the argument of
any slash command:
testdb=> \echo :foo
bar
Note: The arguments of \set are subject to the same substitution
rules as with other commands. Thus you can construct interesting
references such as \set :foo 'something' and get ``soft links''
or ``variable variables'' of Perl or PHP fame, respectively.
Unfortunately (or fortunately?), there is no way to do anything
useful with these constructs. On the other hand, \set bar :foo
is a perfectly valid way to copy a variable.
If you call \set without a second argument, the variable is set, with
an empty string as value. To unset (or delete) a variable, use the com‐
mand \unset.
psql'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 psql. They indicate certain option
settings that can be changed at run time by altering the value of the
variable or 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 con‐
vention, all specially treated variables consist of all upper-case let‐
ters (and possibly numbers and underscores). To ensure maximum compati‐
bility in the future, avoid using such variable names for your own pur‐
poses. A list of all specially treated variables follows.
AUTOCOMMIT
When on (the default), each SQL command is automatically commit‐
ted upon successful completion. To postpone commit in this mode,
you must enter a BEGIN or START TRANSACTION SQL command. When
off or unset, SQL commands are not committed until you explic‐
itly issue COMMIT or END. The autocommit-off mode works by issu‐
ing an implicit BEGIN for you, just before any command that is
not already in a transaction block and is not itself a BEGIN or
other transaction-control command, nor a command that cannot be
executed inside a transaction block (such as VACUUM).
Note: In autocommit-off mode, you must explicitly abandon any
failed transaction by entering ABORT or ROLLBACK. Also keep in
mind that if you exit the session without committing, your work
will be lost.
Note: The autocommit-on mode is PostgreSQL's traditional behav‐
ior, but autocommit-off is closer to the SQL spec. If you prefer
autocommit-off, you may wish to set it in the system-wide psqlrc
file or your ~/.psqlrc file.
DBNAME 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.
ECHO If set to all, 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 -a. If set to queries, psql merely prints all queries
as they are sent to the server. The switch for this is -e.
ECHO_HIDDEN
When this variable is set and a backslash command queries the
database, the query is first shown. This way you can study the
PostgreSQL internals and provide similar functionality in your
own programs. (To select this behavior on program start-up, use
the switch -E.) If you set the variable to the value noexec, the
queries are just shown but are not actually sent to the server
and executed.
ENCODING
The current client character set encoding.
HISTCONTROL
If this variable is set to ignorespace, lines which begin with a
space are not entered into the history list. If set to a value
of ignoredups, lines matching the previous history line are not
entered. A value of ignoreboth 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.
Note: This feature was shamelessly plagiarized from Bash.
HISTFILE
The file name that will be used to store the history list. The
default value is ~/.psql_history. For example, putting
\set HISTFILE ~/.psql_history- :DBNAME
in ~/.psqlrc will cause psql to maintain a separate history for
each database.
Note: This feature was shamelessly plagiarized from Bash.
HISTSIZE
The number of commands to store in the command history. The
default value is 500.
Note: This feature was shamelessly plagiarized from Bash.
HOST 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.
IGNOREEOF
If unset, sending an EOF character (usually Control+D) to an
interactive session of psql will terminate the application. If
set to a numeric value, that many EOF characters are ignored
before the application terminates. If the variable is set but
has no numeric value, the default is 10.
Note: This feature was shamelessly plagiarized from Bash.
LASTOID
The value of the last affected OID, as returned from an INSERT
or lo_insert command. This variable is only guaranteed to be
valid until after the result of the next SQL command has been
displayed.
ON_ERROR_ROLLBACK
When on, if a statement in a transaction block generates an
error, the error is ignored and the transaction continues. When
interactive, such errors are only ignored in interactive ses‐
sions, and not when reading script files. When 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 SAVEPOINT for you, just before
each command that is in a transaction block, and rolls back to
the savepoint on error.
ON_ERROR_STOP
By default, if non-interactive scripts encounter an error, such
as a malformed SQL command or internal meta-command, processing
continues. This has been the traditional behavior of psql but it
is sometimes not desirable. If this variable is set, script pro‐
cessing 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 psql
session but rather using the -f option, psql will return error
code 3, to distinguish this case from fatal error conditions
(error code 1).
PORT The database server port to which you are currently connected.
This is set every time you connect to a database (including pro‐
gram start-up), but can be unset.
PROMPT1
PROMPT2
PROMPT3
These specify what the prompts psql issues should look like. See
Prompting [psql(1)] below.
QUIET This variable is equivalent to the command line option -q. It is
probably not too useful in interactive mode.
SINGLELINE
This variable is equivalent to the command line option -S.
SINGLESTEP
This variable is equivalent to the command line option -s.
USER 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.
VERBOSITY
This variable can be set to the values default, verbose, or
terse to control the verbosity of error reports.
SQL INTERPOLATION
An additional useful feature of psql variables is that you can substi‐
tute (``interpolate'') them into regular SQL statements. The syntax for
this is again to prepend the variable name with a colon (:).
testdb=> \set foo 'my_table'
testdb=> SELECT * FROM :foo;
would then query the table my_table. 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.
Variable interpolation will not be performed into quoted SQL entities.
A popular application of this facility is to refer to the last inserted
OID in subsequent statements to build a foreign key scenario. Another
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.
testdb=> \set content '\'' `cat my_file.txt` '\''
testdb=> INSERT INTO my_table VALUES (:content);
One possible problem with this approach is that my_file.txt might con‐
tain single quotes. These need to be escaped so that they don't cause a
syntax error when the second line is processed. This could be done with
the program sed:
testdb=> \set content '\'' `sed -e "s/'/\\\\\\'/g" < my_file.txt` '\''
Observe the correct number of backslashes (6)! It works this way: After
psql has parsed this line, it passes sed -e "s/'/\\\'/g" < my_file.txt
to the shell. The shell will do its own thing inside the double quotes
and execute sed with the arguments -e and s/'/\\'/g. When sed parses
this it will replace the two backslashes with a single one and then do
the substitution. Perhaps at one point you thought it was great that
all Unix commands use the same escape character. And this is ignoring
the fact that you might have to escape all backslashes as well because
SQL text constants are also subject to certain interpretations. In that
case you might be better off preparing the file externally.
Since colons may legally appear in SQL commands, the following rule
applies: the character sequence ``:name'' is not changed unless
``name'' is the name of a variable that is currently set. In any case
you can escape a colon with a backslash to protect it from substitu‐
tion. (The colon syntax for variables is standard SQL for embedded
query languages, such as ECPG. The colon syntax for array slices and
type casts are PostgreSQL extensions, hence the conflict.)
PROMPTING
The prompts psql issues can be customized to your preference. The three
variables PROMPT1, PROMPT2, and PROMPT3 contain strings and special
escape sequences that describe the appearance of the prompt. Prompt 1
is the normal prompt that is issued when psql 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 SQL COPY command and
you are expected to type in the row values on the terminal.
The value of the selected prompt variable is printed literally, except
where a percent sign (%) is encountered. Depending on the next charac‐
ter, certain other text is substituted instead. Defined substitutions
are:
%M The full host name (with domain name) of the database server, or
[local] if the connection is over a Unix domain socket, or
[local:/dir/name], if the Unix domain socket is not at the com‐
piled in default location.
%m The host name of the database server, truncated at the first
dot, or [local] if the connection is over a Unix domain socket.
%> The port number at which the database server is listening.
%n The database session user name. (The expansion of this value
might change during a database session as the result of the com‐
mand SET SESSION AUTHORIZATION.)
%/ The name of the current database.
%~ Like %/, but the output is ~ (tilde) if the database is your
default database.
%# If the session user is a database superuser, then a #, otherwise
a >. (The expansion of this value might change during a data‐
base session as the result of the command SET SESSION AUTHORIZA‐
TION.)
%R In prompt 1 normally =, but ^ if in single-line mode, and ! if
the session is disconnected from the database (which can happen
if \connect fails). In prompt 2 the sequence is replaced by -,
*, a single quote, a double quote, or a dollar sign, depending
on whether psql expects more input because the command wasn't
terminated yet, because you are inside a /* ... */ comment, or
because you are inside a quoted or dollar-escaped string. In
prompt 3 the sequence doesn't produce anything.
%x Transaction status: an empty string when not in a transaction
block, or * when in a transaction block, or ! when in a failed
transaction block, or ? when the transaction state is indeter‐
minate (for example, because there is no connection).
%digits
The character with the indicated octal code is substituted.
%:name:
The value of the psql variable name. See the section Variables
[psql(1)] for details.
%`command`
The output of command, similar to ordinary ``back-tick'' substi‐
tution.
%[ ... %]
Prompts may contain terminal control characters which, for exam‐
ple, 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 Readline to work properly, these non-
printing control characters must be designated as invisible by
surrounding them with %[ and %]. Multiple pairs of these may
occur within the prompt. For example,
testdb=> \set PROMPT1 '%[%033[1;33;40m%]%n@%/%R%[%033[0m%#%] '
results in a boldfaced (1;) yellow-on-black (33;40) prompt on
VT100-compatible, color-capable terminals.
To insert a percent sign into your prompt, write %%. The default
prompts are '%/%R%# ' for prompts 1 and 2, and '>> ' for prompt 3.
Note: This feature was shamelessly plagiarized from tcsh.
COMMAND-LINE EDITING
psql supports the Readline library for convenient line editing and
retrieval. The command history is automatically saved when psql exits
and is reloaded when psql starts up. Tab-completion is also supported,
although the completion logic makes no claim to be an SQL parser. If
for some reason you do not like the tab completion, you can turn it off
by putting this in a file named .inputrc in your home directory:
$if psql
set disable-completion on
$endif
(This is not a psql but a Readline feature. Read its documentation for
further details.)
ENVIRONMENT
PAGER If the query results do not fit on the screen, they are piped
through this command. Typical values are more or less. The
default is platform-dependent. The use of the pager can be dis‐
abled by using the \pset command.
PGDATABASE
Default connection database
PGHOST
PGPORT
PGUSER Default connection parameters
PSQL_EDITOR
EDITOR
VISUAL Editor used by the \e command. The variables are examined in the
order listed; the first that is set is used.
SHELL Command executed by the \! command.
TMPDIR Directory for storing temporary files. The default is /tmp.
FILES
· Before starting up, psql attempts to read and execute commands from
the system-wide psqlrc file and the user's ~/.psqlrc file. (On Win‐
dows, the user's startup file is named %APPDATA%\post‐
gresql\psqlrc.conf.) See PREFIX/share/psqlrc.sample for information
on setting up the system-wide file. It could be used to set up the
client or the server to taste (using the \set and SET commands).
· Both the system-wide psqlrc file and the user's ~/.psqlrc file can be
made version-specific by appending a dash and the PostgreSQL release
number, for example ~/.psqlrc-8.1.0. A matching version-specific
file will be read in preference to a non-version-specific file.
· The command-line history is stored in the file ~/.psql_history, or
%APPDATA%\postgresql\psql_history on Windows.
NOTES
· In an earlier life psql allowed the first argument of a single-letter
backslash command to start directly after the command, without inter‐
vening whitespace. For compatibility this is still supported to some
extent, but we are not going to explain the details here as this use
is discouraged. If you get strange messages, keep this in mind. For
example
testdb=> \foo
Field separator is "oo".
which is perhaps not what one would expect.
· psql only works smoothly with servers of the same version. That does
not mean other combinations will fail outright, but subtle and not-
so-subtle problems might come up. Backslash commands are particularly
likely to fail if the server is of a different version.
NOTES FOR WINDOWS USERSpsql is built as a ``console application''. Since the Windows console
windows use a different encoding than the rest of the system, you must
take special care when using 8-bit characters within psql. If psql
detects a problematic console code page, it will warn you at startup.
To change the console code page, two things are necessary:
· Set the code page by entering cmd.exe /c chcp 1252. (1252 is a code
page that is appropriate for German; replace it with your value.) If
you are using Cygwin, you can put this command in /etc/profile.
· Set the console font to ``Lucida Console'', because the raster font
does not work with the ANSI code page.
EXAMPLES
The first example shows how to spread a command over several lines of
input. Notice the changing prompt:
testdb=> CREATE TABLE my_table (
testdb(> first integer not null default 0,
testdb(> second text)
testdb-> ;
CREATE TABLE
Now look at the table definition again:
testdb=> \d my_table
Table "my_table"
Attribute | Type | Modifier
-----------+---------+--------------------
first | integer | not null default 0
second | text |
Now we change the prompt to something more interesting:
testdb=> \set PROMPT1 '%n@%m %~%R%# '
peter@localhost testdb=>
Let's assume you have filled the table with data and want to take a
look at it:
peter@localhost testdb=> SELECT * FROM my_table;
first | second
-------+--------
1 | one
2 | two
3 | three
4 | four
(4 rows)
You can display tables in different ways by using the \pset command:
peter@localhost testdb=> \pset border 2
Border style is 2.
peter@localhost testdb=> SELECT * FROM my_table;
+-------+--------+
| first | second |
+-------+--------+
| 1 | one |
| 2 | two |
| 3 | three |
| 4 | four |
+-------+--------+
(4 rows)
peter@localhost testdb=> \pset border 0
Border style is 0.
peter@localhost testdb=> SELECT * FROM my_table;
first second
----- ------
1 one
2 two
3 three
4 four
(4 rows)
peter@localhost testdb=> \pset border 1
Border style is 1.
peter@localhost testdb=> \pset format unaligned
Output format is unaligned.
peter@localhost testdb=> \pset fieldsep ","
Field separator is ",".
peter@localhost testdb=> \pset tuples_only
Showing only tuples.
peter@localhost testdb=> SELECT second, first FROM my_table;
one,1
two,2
three,3
four,4
Alternatively, use the short commands:
peter@localhost testdb=> \a \t \x
Output format is aligned.
Tuples only is off.
Expanded display is on.
peter@localhost testdb=> SELECT * FROM my_table;
-[ RECORD 1 ]-
first | 1
second | one
-[ RECORD 2 ]-
first | 2
second | two
-[ RECORD 3 ]-
first | 3
second | three
-[ RECORD 4 ]-
first | 4
second | four
SEE ALSO
Environment Variables (the documentation)
Application 2005-11-05 PSQL(1)
