table of contents
PSQL(1) | PostgreSQL 9.2.24 Documentation | PSQL(1) |
NAME¶
psql - PostgreSQL interactive terminal
SYNOPSIS¶
psql [option...] [dbname [username]]
DESCRIPTION¶
psql 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
-A, --no-align
-c command, --command=command
command must be either a command string that is completely parsable by the server (i.e., it contains no psql-specific features), or a single backslash command. Thus you cannot mix SQL and psql meta-commands with this option. To achieve that, you could pipe the string into psql, for example: echo '\x \\ SELECT * FROM foo;' | psql. (\\ is the separator meta-command.)
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. Also, only the result of the last SQL command is returned.
Because of these legacy behaviors, putting more than one command in the -c string often has unexpected results. It's better to feed multiple commands to psql's standard input, either using echo as illustrated above, or via a shell here-document, for example:
psql <<EOF \x SELECT * FROM foo; EOF
-d dbname, --dbname=dbname
If this parameter contains an = sign or starts with a valid URI prefix (postgresql:// or postgres://), it is treated as a conninfo string. See Section 31.1, “Database Connection Control Functions”, in the documentation for more information.
-e, --echo-queries
-E, --echo-hidden
-f filename, --file=filename
If filename is - (hyphen), then standard input is read until an EOF indication or \q meta-command. Note however that Readline is not used in this case (much as if -n had been specified).
Using this option is subtly different from writing psql < filename. In general, both will do what you expect, but using -f 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.
-F separator, --field-separator=separator
-h hostname, --host=hostname
-H, --html
-l, --list
-L filename, --log-file=filename
-n, --no-readline
-o filename, --output=filename
-p port, --port=port
-P assignment, --pset=assignment
-q, --quiet
-R separator, --record-separator=separator
-s, --single-step
-S, --single-line
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
-T table_options, --table-attr=table_options
-U username, --username=username
-v assignment, --set=assignment, --variable=assignment
-V, --version
-w, --no-password
Note that this option will remain set for the entire session, and so it affects uses of the meta-command \connect as well as the initial connection attempt.
-W, --password
This option is never essential, since psql will automatically prompt for a password if the server demands password authentication. However, psql will waste a connection attempt finding out that the server wants a password. In some cases it is worth typing -W to avoid the extra connection attempt.
Note that this option will remain set for the entire session, and so it affects uses of the meta-command \connect as well as the initial connection attempt.
-x, --expanded
-X,, --no-psqlrc
-z, --field-separator-zero
-0, --record-separator-zero
-1, --single-transaction
If the script itself uses BEGIN, COMMIT, or 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.
-?, --help
EXIT STATUS¶
psql 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 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 connect 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 of 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 determined at compile time. Since the database server uses the same default, you will not have to specify the port in most cases. The default user name is your operating-system user name, as is the default database name. Note that you cannot just connect to any database under any user name. Your database administrator should have informed you about your access rights.
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 Section 31.14, “Environment Variables”, in the documentation.) It is also convenient to have a ~/.pgpass file to avoid regularly having to type in passwords. See Section 31.15, “The Password File”, in the documentation for more information.
An alternative way to specify connection parameters is in a conninfo string or a URI, which is used instead of a database name. This mechanism give you very wide control over the connection. For example:
$ psql "service=myservice sslmode=require" $ psql postgresql://dbmaster:5433/mydb?sslmode=require
This way you can also use LDAP for connection parameter lookup as described in Section 31.17, “LDAP Lookup of Connection Parameters”, in the documentation. See Section 31.1, “Database Connection Control Functions”, in the documentation for more information on all the available connection options.
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.
If at least one of standard input or standard output are a terminal, then psql sets the client encoding to “auto”, which will detect the appropriate client encoding from the locale settings (LC_CTYPE environment variable on Unix systems). If this doesn't work out as expected, the client encoding can be overridden using the environment variable PGCLIENTENCODING.
Entering SQL Commands¶
In normal operation, psql provides a prompt with the name of the database to which psql is currently connected, followed by the string =>. For example:
$ psql testdb psql (9.2.24) Type "help" for help. testdb=>
At the prompt, the user can 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 notification events generated by LISTEN(7) and 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 make psql more useful for administration or scripting. Meta-commands are often 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 in an argument you can quote it with single quotes. To include a single quote in an argument, write two single quotes within single-quoted text. Anything contained in single quotes is furthermore subject to C-like substitutions for \n (new line), \t (tab), \b (backspace), \r (carriage return), \f (form feed), \digits (octal), and \xdigits (hexadecimal). A backslash preceding any other character within single-quoted text quotes that single character, whatever it is.
Within an argument, text that is enclosed in backquotes (`) is taken as a command line that is passed to the shell. The output of the command (with any trailing newline removed) replaces the backquoted text.
If an unquoted colon (:) followed by a psql variable name appears within an argument, it is replaced by the variable's value, as described in SQL Interpolation.
Some commands take an SQL identifier (such as a table name) as argument. 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 identifier. Within double quotes, paired double quotes reduce to a single double quote in the resulting name. For example, FOO"BAR"BAZ is interpreted as fooBARbaz, and "A weird"" name" becomes A weird" name.
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 \\ (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-command cannot continue beyond the end of the line.
The following meta-commands are defined:
\a
\c or \connect [ -reuse-previous=on|off ] [ dbname [ username ] [ host ] [ port ] | conninfo ]
Where the command omits database name, user, host, or port, the new connection can reuse values from the previous connection. By default, values from the previous connection are reused except when processing a conninfo string. Passing a first argument of -reuse-previous=on or -reuse-previous=off overrides that default. When the command neither specifies nor reuses a particular parameter, the libpq default is used. Specifying any of dbname, username, host or port as - is equivalent to omitting that parameter.
If the new connection is successfully made, the previous connection is closed. If the connection attempt failed (wrong user name, access denied, etc.), the previous connection will only be kept if 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 accidentally acting on the wrong database on the other hand.
Examples:
=> \c mydb myuser host.dom 6432 => \c service=foo => \c "host=localhost port=5432 dbname=mydb connect_timeout=10 sslmode=disable" => \c postgresql://tom@localhost/mydb?application_name=myapp
\C [ title ]
\cd [ directory ]
Tip
To print your current working directory, use \! pwd.
\conninfo
\copy { table [ ( column_list ) ] | ( query ) } { from | to } { filename | stdin | stdout | pstdin | pstdout } [ with ] [ binary ] [ oids ] [ delimiter [ as ] 'character' ] [ null [ as ] 'string' ] [ csv [ header ] [ quote [ as ] 'character' ] [ escape [ as ] 'character' ] [ force quote column_list | * ] [ force not null column_list ] ]
The syntax of the command is similar to that of the SQLCOPY(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 ... from stdin | to stdout reads/writes based on the command 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 output, 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 SQLCOPY command because all data must pass through the client/server connection. For large amounts of data the SQL command might be preferable.
\copyright
\d[S+] [ pattern ]
For some types of relation, \d shows additional information for each column: column values for sequences, indexed expression for indexes and foreign data wrapper options for foreign tables.
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, the view definition if the relation is a view.
By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects.
Note
If \d is used without a pattern argument, it is equivalent to \dtvsE which will show a list of all visible tables, views, sequences and foreign tables. This is purely a convenience measure.
\da[S] [ pattern ]
\db[+] [ pattern ]
\dc[S+] [ pattern ]
\dC[+] [ pattern ]
\dd[S] [ pattern ]
\dd displays descriptions for objects matching the pattern, or of visible objects of the appropriate type if no argument is given. But in either case, only objects that have a description are listed. By default, only user-created objects are shown; supply a pattern or the S modifier to include system objects.
Descriptions for objects can be created with the COMMENT(7)SQL command.
\ddp [ pattern ]
The ALTER DEFAULT PRIVILEGES (ALTER_DEFAULT_PRIVILEGES(7)) command is used to set default access privileges. The meaning of the privilege display is explained under GRANT(7).
\dD[S+] [ pattern ]
\dE[S+] [ pattern ], \di[S+] [ pattern ], \ds[S+] [ pattern ], \dt[S+] [ pattern ], \dv[S+] [ pattern ]
\des[+] [ pattern ]
\det[+] [ pattern ]
\deu[+] [ pattern ]
Caution
\deu+ might also display the user name and password of the remote user, so care should be taken not to disclose them.
\dew[+] [ pattern ]
\df[antwS+] [ pattern ]
Tip
To look up functions taking arguments or returning values of a specific type, use your pager's search capability to scroll through the \df output.
\dF[+] [ pattern ]
\dFd[+] [ pattern ]
\dFp[+] [ pattern ]
\dFt[+] [ pattern ]
\dg[+] [ pattern ]
\dl
\dL[S+] [ pattern ]
\dn[S+] [ pattern ]
\do[S] [ pattern ]
\dO[S+] [ pattern ]
\dp [ pattern ]
The GRANT(7) and REVOKE(7) commands are used to set access privileges. The meaning of the privilege display is explained under GRANT(7).
\drds [ role-pattern [ database-pattern ] ]
The ALTER ROLE (ALTER_ROLE(7)) and ALTER DATABASE (ALTER_DATABASE(7)) commands are used to define per-role and per-database configuration settings.
\dT[S+] [ pattern ]
\du[+] [ pattern ]
\dx[+] [ pattern ]
\e or \edit [ filename ] [ line_number ]
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 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 \g to send it, or \r to cancel.
If a line number is specified, psql will position the cursor on the specified line of the file or query buffer. Note that if a single all-digits argument is given, psql assumes it is a line number, not a file name.
Tip
See under ENVIRONMENT for how to configure and customize your editor.
\echo text [ ... ]
=> \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 might wish to use \qecho instead of this command.
\ef [ function_description [ line_number ] ]
The target function can be specified by name alone, or by name and arguments, for example foo(integer, text). The argument types must be given if there is more than one function of the same name.
If no function is specified, a blank CREATE FUNCTION template is presented for editing.
If a line number is specified, psql 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.)
Tip
See under ENVIRONMENT for how to configure and customize your editor.
\encoding [ encoding ]
\f [ string ]
\g [ filename ], \g [ |command ]
\h or \help [ command ]
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 or \html
\i or \include filename
If filename is - (hyphen), then standard input is read until an EOF indication or \q meta-command. This can be used to intersperse interactive input with input from files. Note that Readline behavior will be used only if it is active at the outermost level.
Note
If you want to see the lines on the screen as they are read you must set the variable ECHO to all.
\ir or \include_relative filename
\l (or \list), \l+ (or \list+)
\lo_export loid filename
Tip
Use \lo_list to find out the large object's OID.
\lo_import filename [ comment ]
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 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 \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
\lo_unlink loid
Tip
Use \lo_list to find out the large object's OID.
\o or \out [ filename ], \o or \out [ |command ]
“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 or \print
\password [ username ]
\prompt [ text ] name
By default, \prompt uses the terminal for input and output. However, if the -f command line switch was used, \prompt uses standard input and standard output.
\pset option [ value ]
Adjustable printing options are:
border
columns
expanded (or x)
fieldsep
fieldsep_zero
footer
format
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).
aligned format is the standard, human-readable, nicely formatted text output; this is the default.
wrapped format is like 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 columns option. Note that psql will not attempt to wrap column header titles; therefore, wrapped format behaves the same as aligned if the total width needed for column headers exceeds the target.
The html, latex, and 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 HTML, but in LaTeX you must have a complete document wrapper.)
linestyle
ascii style uses plain ASCII characters. Newlines in data are shown using a + symbol in the right-hand margin. When the wrapped format wraps data from one line to the next without a newline character, a dot (.) is shown in the right-hand margin of the first line, and again in the left-hand margin of the following line.
old-ascii style uses plain ASCII characters, using the formatting style used in PostgreSQL 8.4 and earlier. Newlines in data are shown using a : 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 ; symbol is used in place of the left-hand column separator.
unicode 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.
When the border setting is greater than zero, this option also determines the characters with which the border lines are drawn. Plain ASCII characters work everywhere, but Unicode characters look nicer on displays that recognize them.
null
numericlocale
pager
When the pager option is off, the pager program is not used. When the pager option is on, the pager is used when appropriate, i.e., when the output is to a terminal and will not fit on the screen. The pager option can also be set to always, which causes the pager to be used for all terminal output regardless of whether it fits on the screen. \pset pager without a value toggles pager use on and off.
recordsep
recordsep_zero
tableattr (or T)
title
tuples_only (or t)
Illustrations of how these different formats look can be seen in the EXAMPLES 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 any arguments. In the future this case might show the current status of all printing options.
\q or \quit
\qecho text [ ... ]
\r or \reset
\s [ filename ]
\set [ name [ value [ ... ] ] ]
\set without any arguments displays the names and values of all currently-set psql variables.
Valid variable names can contain letters, digits, and underscores. See the section Variables 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 documented in the section about variables.
\setenv name [ value ]
testdb=> \setenv PAGER less testdb=> \setenv LESS -imx4F
\sf[+] function_description
The target function can be specified by name alone, or by name and arguments, for example foo(integer, text). The argument types must be given if there is more than one function of the same name.
If + is appended to the command name, then the output lines are numbered, with the first line of the function body being line 1.
\t
\T table_options
\timing [ on | off ]
\unset name
\w or \write filename, \w or \write |command
\x [ on | off | auto ]
\z [ pattern ]
This is an alias for \dp (“display privileges”).
\! [ command ]
\?
Patterns
The various \d commands accept a pattern 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, \dt FOO will display the table named 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, \dt "FOO""BAR" will display the table named FOO"BAR (not foo"bar). Unlike the normal rules for SQL names, you can put double quotes around just part of a pattern, for instance \dt FOO"FOO"BAR will display the table named fooFOObar.
Whenever the pattern parameter is omitted completely, the \d commands display all objects that are visible in the current schema search path — this is equivalent to using * as the pattern. (An object is said to be 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 *.* as the pattern.
Within a pattern, * matches any sequence of characters (including no characters) and ? matches any single character. (This notation is comparable to Unix shell file name patterns.) For example, \dt int* displays tables whose names begin with int. But within double quotes, * and ? lose these special meanings and are just matched literally.
A pattern that contains a dot (.) is interpreted as a schema name pattern followed by an object name pattern. For example, \dt foo*.*bar* displays all tables whose table name includes bar that are in schemas whose schema name starts with 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.
Advanced users can use regular-expression notations such as character classes, for example [0-9] to match any digit. All regular expression special characters work as specified in Section 9.7.3, “POSIX Regular Expressions”, in the documentation, except for . which is taken as a separator as mentioned above, * which is translated to the regular-expression notation .*, ? which is translated to ., and $ which is matched literally. You can emulate these pattern characters at need by writing ? for ., (R+|) for R*, or (R|) for R?. $ 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, $ is automatically appended to your pattern). Write * 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 \do).
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. The name must consist of letters (including non-Latin letters), digits, and underscores.
To set a variable, use the psql meta-command \set. For example,
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, for example:
testdb=> \echo :foo bar
This works in both regular SQL commands and meta-commands; there is more detail in SQL Interpolation, below.
If you call \set without a second argument, the variable is set, with an empty string as value. To unset (i.e., delete) a variable, use the command \unset. To show the values of all variables, call \set without any argument.
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.
A number of these variables are treated specially by psql. They represent certain option settings that can be changed at run time by altering the value of the variable, or in some cases represent changeable state of psql. Although you can use these variables for other purposes, this is not recommended, as the program behavior might grow really strange really quickly. By convention, all specially treated variables' names consist of all upper-case ASCII letters (and possibly digits and underscores). To ensure maximum compatibility in the future, avoid using such variable names for your own purposes. A list of all specially treated variables follows.
AUTOCOMMIT
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 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 psqlrc file or your ~/.psqlrc file.
COMP_KEYWORD_CASE
DBNAME
ECHO
ECHO_HIDDEN
ENCODING
FETCH_COUNT
Tip
Although you can use any output format with this feature, the default aligned format tends to look bad because each group of FETCH_COUNT rows will be formatted separately, leading to varying column widths across the row groups. The other output formats work better.
HISTCONTROL
Note
This feature was shamelessly plagiarized from Bash.
HISTFILE
\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
Note
This feature was shamelessly plagiarized from Bash.
HOST
IGNOREEOF
Note
This feature was shamelessly plagiarized from Bash.
LASTOID
ON_ERROR_ROLLBACK
ON_ERROR_STOP
PORT
PROMPT1, PROMPT2, PROMPT3
QUIET
SINGLELINE
SINGLESTEP
USER
VERBOSITY
SQL Interpolation
A key feature of psql variables is that you can substitute (“interpolate”) them into regular SQL statements, as well as the arguments of meta-commands. Furthermore, psql provides facilities for ensuring that variable values used as SQL literals and identifiers are properly quoted. The syntax for interpolating a value without any quoting is to prepend the variable name with a colon (:). For example,
testdb=> \set foo 'my_table' testdb=> SELECT * FROM :foo;
would query the table my_table. Note that this may be unsafe: the value of the variable is copied literally, so it can contain unbalanced quotes, or even backslash commands. You must make sure that it makes sense where you put it.
When a value is to be used as an SQL literal or identifier, it is safest to arrange for it to be quoted. To quote the value of a variable as an SQL literal, write a colon followed by the variable name in single quotes. To quote the value as an SQL identifier, write a colon followed by the variable name in double quotes. These constructs deal correctly with quotes and other special characters embedded within the variable value. The previous example would be more safely written this way:
testdb=> \set foo 'my_table' testdb=> SELECT * FROM :"foo";
Variable interpolation will not be performed within quoted SQL literals and identifiers. Therefore, a construction such as ':foo' doesn't work to produce a quoted literal from a variable's value (and it would be unsafe if it did work, since it wouldn't correctly handle quotes embedded in the value).
One example use of this mechanism is to copy the contents of a file into a table column. First load the file into a variable and then interpolate the variable's value as a quoted string:
testdb=> \set content `cat my_file.txt` testdb=> INSERT INTO my_table VALUES (:'content');
(Note that this still won't work if my_file.txt contains NUL bytes. psql does not support embedded NUL bytes in variable values.)
Since colons can legally appear in SQL commands, an apparent attempt at interpolation (that is, :name, :'name', or :"name") is not replaced unless the named variable is currently set. In any case, you can escape a colon with a backslash to protect it from substitution.
The colon syntax for variables is standard SQL for embedded query languages, such as ECPG. The colon syntaxes for array slices and type casts are PostgreSQL extensions, which can sometimes conflict with the standard usage. The colon-quote syntax for escaping a variable's value as an SQL literal or identifier is a psql extension.
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 entry, for example because the command was not terminated with a semicolon or a quote was not closed. Prompt 3 is issued when you are running an SQLCOPY FROM STDIN command and you need to type in a row value on the terminal.
The value of the selected prompt variable is printed literally, except where a percent sign (%) is encountered. Depending on the next character, certain other text is substituted instead. Defined substitutions are:
%M
%m
%>
%n
%/
%~
%#
%R
%x
%digits
%:name:
%`command`
%[ ... %]
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.
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¶
COLUMNS
PAGER
PGDATABASE, PGHOST, PGPORT, PGUSER
PSQL_EDITOR, EDITOR, VISUAL
The built-in default editors are vi on Unix systems and notepad.exe on Windows systems.
PSQL_EDITOR_LINENUMBER_ARG
PSQL_EDITOR_LINENUMBER_ARG='+' PSQL_EDITOR_LINENUMBER_ARG='--line '
The default is + on Unix systems (corresponding to the default editor vi, and useful for many other common editors); but there is no default on Windows systems.
PSQL_HISTORY
PSQLRC
SHELL
TMPDIR
This utility, like most other PostgreSQL utilities, also uses the environment variables supported by libpq (see Section 31.14, “Environment Variables”, in the documentation).
FILES¶
psqlrc and ~/.psqlrc
The system-wide startup file is named psqlrc and is sought in the installation's “system configuration” directory, which is most reliably identified by running pg_config --sysconfdir. By default this directory will be ../etc/ relative to the directory containing the PostgreSQL executables. The name of this directory can be set explicitly via the PGSYSCONFDIR environment variable.
The user's personal startup file is named .psqlrc and is sought in the invoking user's home directory. On Windows, which lacks such a concept, the personal startup file is named %APPDATA%\postgresql\psqlrc.conf. The location of the user's startup file can be set explicitly via the PSQLRC environment variable.
Both the system-wide startup file and the user's personal startup file can be made psql-version-specific by appending a dash and the PostgreSQL major or minor release number to the file name, for example ~/.psqlrc-9.2 or ~/.psqlrc-9.2.5. The most specific version-matching file will be read in preference to a non-version-specific file.
.psql_history
The location of the history file can be set explicitly via the PSQL_HISTORY environment variable.
NOTES¶
NOTES FOR WINDOWS USERS¶
psql 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:
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
2017-11-06 | PostgreSQL 9.2.24 |