Interactive command-line interface for Greenplum Database
psql [<option> ...] [<dbname> [<username>]]
psql
is a terminal-based front-end to Greenplum Database. It enables you to type in queries interactively, issue them to Greenplum Database, 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.
Specifies that psql
is to execute the specified command string, and then exit. This is useful in shell scripts. command must be either a command string that is completely parseable by the server, 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
, like this:
echo '\x \\ SELECT * FROM foo;' | psql
(\\
is the separator meta-command.)
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.
Specifies the name of the database to connect to. This is equivalent to specifying dbname as the first non-option argument on the command line.
conninfo
string; for example you can pass
'dbname=postgres user=username password=mypass'
as
dbname
.
\d
and other backslash commands. You can use this to study
psql
's internal operations.
psql
terminates. If filename is
-
(hyphen), then standard input is read. 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.
\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
.
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.
\pset tuples_only
and is provided for convenience.
\pset
for details.
\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.
psql
version and exit.
psqlrc
file nor the user's
~/.psqlrc
file).
When psql
executes a script with the -f
option, adding this option wraps BEGIN/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.
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.
psql
command line arguments, and exit.
Connection Options
The host name of the machine on which the Greenplum master database server is running. If not specified, reads from the environment variable PGHOST
or defaults to localhost.
psql
on the master host, if the host value begins with a slash, it is used as the directory for the UNIX-domain socket.
PGPORT
or defaults to 5432.
PGUSER
or defaults to the current system role name.
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.
Never issue a password prompt. If the server requires password authentication and a password is not available by other means such as a .pgpass 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.
\connect
as well as the initial connection attempt.
psql
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.
Connecting to a Database
psql
is a client application for Greenplum Database. 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 Greenplum master server and what database 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 these options are required; there are useful defaults. If you omit the host name, psql
will connect via a UNIX-domain socket to a master server on the local host, or via TCP/IP to localhost
on machines that do not have UNIX-domain sockets. The default master port number is 5432. If you use a different port for the master, you must specify the port. The default database 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.
When the defaults are not right, you can save yourself some typing by setting any or all of the environment variables PGAPPNAME
, PGDATABASE
, PGHOST
, PGPORT
, and PGUSER
to appropriate values.
It is also convenient to have a ~/.pgpass
file to avoid regularly having to type in passwords. This file should reside in your home directory and contain lines of the following format:
<hostname>:<port>:<database>:<username>:<password>
The permissions on .pgpass
must disallow any access to world or group (for example: chmod 0600 ~/.pgpass
). If the permissions are less strict than this, the file will be ignored. (The file permissions are not currently checked on Microsoft Windows clients, however.)
If the connection could not be made for any reason (insufficient privileges, server is not running, etc.), psql
will return an error and terminate.
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 a regular user or =# for a superuser. For example:
testdb=>
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.
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, use two single quotes. 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 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 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-command cannot continue beyond the end of the line.
The following meta-commands are defined:
\pset
for a more general solution.
\!pwd
.
\pset title
.
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, and a safety mechanism that scripts are not accidentally acting on the wrong database.
TCP/IP
, etc.), the host, and the port.
Performs a frontend (client) copy. This is an operation that runs an SQL COPY
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
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.
COPY
command because all data must pass through the client/server connection.
For each relation (table, external table, view, index, or sequence) matching the relation 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 relation is a view.
\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. \d
or \d+
specified with the root partition table or child partition table displays information about the table including partition keys on the current level of the partition table. The command \d+
also displays the immediate child partitions of the table and whether the child partition is an external table or regular table. \d+
displays the storage options for a table. For append-optimized tables, the options are displayed for the table. For column-oriented tables, storage options are displayed for each column.\dS
is identical, except that system information is displayed as well as user information. For example, \dt
displays user tables, but not system tables; \dtS
displays both user and system tables. Both these commands can take the +
parameter to display additional information, as in \dt+
and \dtS+
. \d
is used without a pattern argument, it is equivalent to \dtvs
which will show a list of all tables, views, and sequences.\df+
is used, additional information about each function, including language and description, is shown. To reduce clutter,
\df
does not show data type I/O functions. This is implemented by ignoring functions that accept or return type
cstring
.
i
,
s
,
t
,
P
,
v
,
E
,
S
stand for index, sequence, table, parent table, view, external table, 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 command name, each object is listed with its associated description, if any. If a pattern is specified, only objects whose names match the pattern are listed.
\lo_list
, which shows a list of large objects.
+
is appended to the command name, each object is listed with its associated permissions and description, if any.
GRANT
and
REVOKE
commands are used to set access privileges.
\dT+
shows extra information.
\dx
and
\dx+
are functionally equivalent.
If a file name 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 temporary 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.
psql
searches the environment variables
PSQL_EDITOR
,
EDITOR
, 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 Windows systems.
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.
\o
command to redirect your query output you may wish to use
\qecho
instead of this command.
|
). See also
\pset
for a generic way of setting output options.
\g
is virtually equivalent to a semicolon. A
\g
with argument is a one-shot alternative to the
\o
command.
psql
will list all the commands for which syntax help is available. Use an asterisk (*) to show syntax help on all SQL commands. To simplify typing, commands that consist of several words do not have to be quoted.
\pset
about setting other output options.
ECHO
to all.
+
is appended to the command name, database descriptions are also displayed.
lo_export
, which acts with the permissions of the user that the database server runs as and on the server's file system. Use
\lo_list
to find out the large object's OID.
Stores the file into a large object. Optionally, it associates the given comment with the object. Example:
mydb=> \lo_import '/home/gpadmin/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
to find out the large object's OID.
\d
), but not error messages. To intersperse text output in between query results, use
'echo
.
ALTER ROLE
command. This makes sure that the new password does not appear in cleartext in the command history, the server log, or elsewhere.
Prompts the user to set a variable name. Optionally, you can specify a prompt. Enclose prompts longer than one word in single quotes.
This command sets options affecting the output of query result tables. print_option describes which option is to be set. Adjustable printing options are:
format
– Sets the output format to one of unaligned
, aligned
, html
, latex
, troff-ms
, or wrapped
. First letter abbreviations are allowed. Unaligned writes all columns of a row on a line, separated by the currently active field separator. This is intended to create output that might be intended to be read in by other programs. Aligned mode is the standard, human-readable, 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.) aligned
parameter , but wraps wide data values across lines to make the output fit in the target column width. The target width is set with the columns
option. To specify the column width and select the wrapped format, use two \pset commands; for example, to set the with to 72 columns and specify wrapped format, use the commands \pset columns 72
and then \pset format wrapped
. psql
does not attempt to wrap column header titles, the wrapped format behaves the same as aligned if the total width needed for column headers exceeds the target.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 border=...
attribute, in the others only values 0
(no border), 1
(internal dividing lines), and 2
(table frame) make sense.columns
– Sets the target width for the wrapped
format, and also the width limit for determining whether output is wide enough to require the pager. The default is zero. Zero causes the target width to be controlled by the environment variable COLUMNS
, or the detected screen width if COLUMNS
is not set. In addition, if columns
is zero then the wrapped format affects screen output only. If columns is nonzero then file and pipe output is wrapped to that width as well. \pset format wrapped
to enable the wrapped format.expanded
| 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 would not fit on the screen in the normal horizontal mode. Expanded mode is supported by all four output formats.linestyle
[unicode
| ascii
| old-ascii
] – Sets the border line drawing style to one of unicode, ascii, or old-ascii. Unique abbreviations, including one letter, are allowed for the three styles. The default setting is ascii
. This option only affects the aligned
and wrapped
output formats. ascii
– 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. 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 'string'
– The second argument is a string to print whenever a column is null. The default is not to print anything, which can easily be mistaken for an empty string. For example, the command \pset``null '(empty)'
displays (empty) in null columns.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 vertical bar).footer
– Toggles the display of the default footer (x rows).numericlocale
– Toggles the display of a locale-aware character to separate 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.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
| 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
.tuples_only
| t
[novalue | on | off] – The \pset tuples_only
command by itselt toggles between tuples only and full display. The values on and off set the tuples display, regardless of the current setting. Full display may show extra information such as column headers, titles, and various footers. In tuples only mode, only actual table data is shown The \t
command is equivalent to \pset``tuples_only
and is provided for convenience.pager
– Controls the use of a pager for query and psql
help output. When on
, 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 off
, the pager is not used. When on
, the pager is used only when appropriate. Pager can also be set to always
, which causes the pager to be always used.psql
program.
\echo
except that the output will be written to the query output channel, as set by
\o
.
Sets the internal variable name to value 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 \unset
command.
Valid variable names can contain characters, digits, and underscores. See "Variables" in Advanced Features. 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 topic about variables.
SET
.
\t
command by itself toggles a display of output column name headings and row count footer. The values
on
and
off
set the tuples display, regardless of the current setting. This command is equivalent to
\pset tuples_only
and is provided for convenience.
\timing
command by itself toggles a display of how long each SQL statement takes, in milliseconds. The values
on
and
off
set the time display, regardless of the current setting.
\dp
.
psql
backslash commands.
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
.
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 all 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 starts with 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. All regular expression special characters work as specified in the PostgreSQL documentation on regular expressions, except for .
which is taken as a separator as mentioned above, *
which is translated to the regular-expression notation .*
, and ?
which is translated to ..
You can emulate these pattern characters at need by writing ?
for .,``(R+|)
for R*
, or (R|)
for R?
. Remember that the pattern must match the whole name, unlike the usual interpretation of regular expressions; 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 (such as the argument of \do
).
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 the pattern *.
To see all objects in the database, use the pattern *.*.
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, 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 command \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 behave unexpectedly. 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 are as follows:
When on (the default), each SQL command is automatically committed 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 explicitly issue COMMIT
or END
. The autocommit-on mode works by issuing 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
).
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.
~/.psqlrc
file.
-a
. If set to queries,
psql
merely prints all queries as they are sent to the server. The switch for this is
-e
.
-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.
If this variable is set to an integer value > 0, the results of SELECT
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 may fail after having already displayed some rows.
FETCH_COUNT
rows will be formatted separately, leading to varying column widths across the row groups. The other output formats work better.
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.
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
~/.psqlrc
will cause
psql
to maintain a separate history for each database.
EOF
character (usually
CTRL+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
.
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.
SAVEPOINT
for you, just before each command that is in a transaction block, and rolls back to the savepoint on error.
psql
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
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).
psql
issues should look like. See "Prompting".
-q
. It is not very useful in interactive mode.
-S
.
-s
.
default
,
verbose
, or
terse
to control the verbosity of error reports.
SQL Interpolation
An additional useful feature of psql
variables is that you can substitute (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 problem with this approach is that my_file.txt
might contain 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`
''''
If you are using non-standard-conforming strings then you'll also need to double backslashes. This is a bit tricky:
testdb=> \set content '''' `sed -e "s/'/''/g" -e
's/\\/\\\\/g' < my_file.txt` ''''
Note the use of different shell quoting conventions so that neither the single quote marks nor the backslashes are special to the shell. Backslashes are still special to sed
, however, so we need to double them.
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 substitution. (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 Greenplum Database 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 character, certain other text is substituted instead. Defined substitutions are:
[local]
if the connection is over a UNIX domain socket, or
[local:/dir/name]
, if the UNIX domain socket is not at the compiled in default location.
[local]
if the connection is over a UNIX domain socket.
SET SESSION AUTHORIZATION
.)
%/
, but the output is
~
(tilde) if the database is your default database.
SET SESSION AUTHORIZATION
.)
\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.
psql
variable name. See "Variables" in
Advanced Features for details.
Prompts may 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 line editing 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%]%#'
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.
Command-Line Editing
psql
supports the NetBSD libedit 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
more
or
less
. The default is platform-dependent. The use of the pager can be deactivated by using the
\pset
command.
\e
command. The variables are examined in the order listed; the first that is set is used.
\!
command.
/tmp
.
Before starting up, psql
attempts to read and execute commands from the user's ~/.psqlrc
file.
The command-line history is stored in the file ~/.psql_history
.
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.
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:
Set the code page by entering:
cmd.exe /c chcp 1252
1252
is a character encoding of the Latin alphabet, used by Microsoft Windows for English and some other Western languages. 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.
Start psql
in interactive mode:
psql -p 54321 -U sally mydatabase
In psql
interactive mode, 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
Look at the table definition:
testdb=> \d my_table
Table "my_table"
Attribute | Type | Modifier
-----------+---------+--------------------
first | integer | not null default 0
second | text |
Run psql
in non-interactive mode by passing in a file containing SQL commands:
psql -f /home/gpadmin/test/myscript.sql