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RedHat 9 (Linux i386) - man page for psql (redhat section 1)

PSQL(1) 			  PostgreSQL Client Applications			  PSQL(1)

       psql - PostgreSQL interactive terminal

       psql [ options ] [ dbname [ user ] ]

       psql is a terminal-based front-end to PostgreSQL. It enables you to type in queries inter-
       actively, 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.


	      Print all the lines to the screen 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.


	      Switches to unaligned output mode. (The default output mode is otherwise aligned.)

       -c query

       --command query
	      Specifies that psql is to execute one query string, query, and then exit.  This  is
	      useful in shell scripts.

	      query  must  be  either  a  query string that is completely parsable by the backend
	      (i.e., it contains no psql specific features), or it is 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.

       -d dbname

       --dbname dbname
	      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.


	      Show  all  queries  that are sent to the backend. This is equivalent to setting the
	      variable ECHO to queries.


	      Echoes the actual queries generated by \d and other backslash commands. You can use
	      this  if	you wish to include similar functionality into your own programs. This is
	      equivalent to setting the variable ECHO_HIDDEN from within psql.

       -f filename

       --file filename
	      Use the file filename as the source of queries instead of reading queries  interac-
	      tively.  After the file is processed, psql terminates. This is in many ways equiva-
	      lent to the internal command \i.

	      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. 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. This is equivalent to \pset fieldsep or \f.

       -h hostname

       --host hostname
	      Specifies  the host name of the machine on which the postmaster is running. If host
	      begins with a slash, it is used as the directory for the Unix-domain socket.


       --html Turns on HTML tabular output. This is equivalent to \pset format	html  or  the  \H


       --list Lists  all  available  databases,  then  exits.  Other  non-connection  options are
	      ignored. This is similar to the internal command \list.

       -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/IP port or, by omission, the local Unix domain socket file exten-
	      sion on which the postmaster 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.


	      Specifies  that psql should do its work quietly. By default, it prints welcome mes-
	      sages and various informational output. If this option is used, none of  this  hap-
	      pens.  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. This is equivalent to  the  \pset	recordsep


	      Run  in single-step mode. That means the user is prompted before each query is sent
	      to the backend, with the option to cancel execution as  well.  Use  this	to  debug


	      Runs in single-line mode where a newline terminates a query, 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.


	      Turn  off  printing  of  column names and result row count footers, etc. It is com-
	      pletely equivalent to the \t meta-command.

       -T table_options

       --table-attr table_options
	      Allows you to specify options to be placed within the HTML table tag. See \pset for

       -u     Makes psql prompt for the user name and password before connecting to the database.

	      This  option  is	deprecated,  as it is conceptually flawed.  (Prompting for a non-
	      default user name and prompting for a password because the backend requires it  are
	      really  two  different things.) You are encouraged to look at the -U and -W options

       -U username

       --username username
	      Connects 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
	      Performs	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 overwrit-
	      ten later.


	      Shows the psql version.


	      Requests that psql should prompt for a password before connecting  to  a	database.
	      This  will  remain set for the entire session, even if you change the database con-
	      nection with the meta-command \connect.

	      In the current version, psql automatically issues a password  prompt  whenever  the
	      backend  requests  password  authentication.  Because  this is currently based on a
	      hack, the automatic recognition might mysteriously fail, hence this option to force
	      a prompt. If no password prompt is issued and the backend requires password authen-
	      tication the connection attempt will fail.


	      Turns on extended row format mode. This is equivalent to the command \x.


	      Do not read the start-up file ~/.psqlrc.


       --help Shows help about psql command line arguments.

       Long options are not available on all platforms.

       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 backend went bad and the ses-
       sion is not interactive, and 3  if  an  error  occurred	in  a  script  and  the  variable
       ON_ERROR_STOP was set.

       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 also given). Not all these options are required, defaults do
       apply.  If  you omit the host name, psql will connect via a Unix domain socket to a server
       on the local host. The default port number is compile-time determined.  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. To save you some typing you can also  set  the
       environment variables PGDATABASE, PGHOST, PGPORT and PGUSER to appropriate values.

       If  the	connection could not be made for any reason (e.g., insufficient privileges, post-
       master is not running on the server, etc.), psql will return an error and terminate.

       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
       Welcome to psql 7.3rc2, the PostgreSQL interactive terminal.

       Type:  \copyright for distribution terms
	      \h for help with SQL commands
	      \? for help on internal slash commands
	      \g or terminate with semicolon to execute query
	      \q to quit


       At  the prompt, the user may type in SQL queries.  Ordinarily, input lines are sent to the
       backend when a query-terminating semicolon is reached. An end of line does not terminate a
       query!  Thus  queries  can be spread over several lines for clarity. If the query was sent
       and without error, the query results are displayed on the screen.

       Whenever a query is executed, psql also polls for asynchronous notification events  gener-
       ated by LISTEN [listen(7)] and NOTIFY [notify(7)].

       Anything  you  enter in psql that begins with an unquoted backslash is a psql meta-command
       that is processed by psql itself. These commands  are  what  makes  psql  interesting  for
       administration  or  scripting.  Meta-commands  are more commonly called slash or backslash

       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 sin-
       gle quotes is furthermore subject to C-like substitutions for \n  (new  line),  \t  (tab),
       \digits, \0digits, and \0xdigits (the character with the given decimal, octal, or hexadec-
       imal code).

       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 regarding  double  quotes:  an  identifier  without  double
       quotes  is coerced to lower-case, while whitespace within double quotes is included in the

       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 queries, 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 con-
       tinue beyond the end of the line.

       The following meta-commands are defined:

       \a     If the current table output format is unaligned, switch to aligned.  If it  is  not
	      unaligned,  set  it to unaligned. This command is kept for backwards compatibility.
	      See \pset for a general solution.

       \cd [directory]
	      Change the current working directory to directory. Without argument, change to  the
	      current user's home directory.

	      Tip: To print your current working directory, use \!pwd.

       \C [ title ]
	      Set  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 com-
	      mand derives from ``caption'', 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 current 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 data-
	      base as the default user (as you would have gotten by  starting  psql  without  any

	      If the connection attempt failed (wrong user name, access denied, etc.), the previ-
	      ous connection will be kept if and only if psql is in interactive mode.  When  exe-
	      cuting  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 data-
	      base 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 backend's reading or writing the specified
	      file, psql reads or writes the file and routes the data between the backend 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	(see  its
	      description  for	the  details).	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.

	      Tip:  This  operation  is not as efficient as the SQL COPY command because all data
	      must pass through the client/server IP or socket connection. For large  amounts  of
	      data the other technique may be preferable.

	      Note:  Note  the	difference in interpretation of stdin and stdout between frontend
	      and backend copies: in a frontend copy these always refer to psql's input and  out-
	      put  stream.  On a backend copy stdin comes from wherever the COPY itself came from
	      (for example, a script run with the -f option), and stdout refers to the query out-
	      put stream (see \o meta-command below).

	      Shows the copyright and distribution terms of PostgreSQL.

       \d [ pattern ]
	      For  each relation (table, view, index, or sequence) matching the pattern, show all
	      columns, their types, 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.  (``Matching the  pattern''  is  defined

	      The  command form \d+ is identical, but any comments associated with the table col-
	      umns are shown as well.

	      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

       \da [ pattern ]
	      Lists all available aggregate functions, together with the data type  they  operate
	      on.  If  pattern	(a regular expression) is specified, only matching aggregates are

       \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 exam-

	      => \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 ON SQL command.

	      Note: PostgreSQL stores the object descriptions in the pg_description system table.

       \dD [ pattern ]
	      Lists all available domains (derived types). If pattern is specified, only matching
	      domains are shown.

       \df [ pattern ]
	      Lists  available	functions, together with their argument and return types. If pat-
	      tern is specified, only matching functions are shown. If the  form  \df+	is  used,
	      additional  information about each function, including language and description, is

	      Note: To reduce clutter, \df does not show data type I/O functions. This is  imple-
	      mented by ignoring functions that accept or return type cstring.

       \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 command name, each object is listed
	      with its associated description, if any.

	      If a pattern is specified, only objects whose name matches the pattern are listed.

       \dl    This is an alias for \lo_list, which shows a list of large objects.

       \do [ pattern ]
	      Lists available operators with their operand and return types.   If  a  pattern  is
	      specified, only operators whose name matches the pattern are listed.

       \dp [ pattern ]
	      Produces	a  list of all available tables with their associated access permissions.
	      If a pattern is specified, only tables whose name matches the pattern are listed.

	      The commands grant(7) and  revoke(7)  are  used  to  set	access	permissions.  See
	      grant(7) for more information.

       \dT [ pattern ]
	      Lists  all data types or only those that match pattern. The command form \dT+ shows
	      extra information.

       \du [ pattern ]
	      Lists all database users, 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 buf-
	      fer 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  con-
	      tains)  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, EDITOR,  and  VISUAL  (in
	      that order) for an editor to use. If all of them are unset, /bin/vi is run.

       \echo text [ ... ]
	      Prints the arguments to the standard output, separated by one space and followed by
	      a newline. This can be useful to intersperse information in the output of  scripts.
	      For example:

	      => \echo `date`
	      Tue Oct 26 21:40:57 CEST 1999

	      If the first argument is an unquoted -n the 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 encoding, if you are using multibyte encodings.  Without	an  argu-
	      ment, this command shows the current encoding.

       \f [ string ]
	      Sets  the  field separator for unaligned query output. The default is pipe (|). See
	      also \pset for a generic way of setting output options.

       \g [ { filename | |command } ]
	      Sends the current query input buffer to the backend and optionally saves the output
	      in  filename  or	pipes the output into a separate Unix shell to execute command. A
	      bare \g is virtually equivalent to a semicolon. A \g  with  argument  is	a  ``one-
	      shot'' alternative to the \o command.

       \help (or \h) [ command ]
	      Give  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 con-
	      venience, 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)
	      List all the databases in the server as well as their owners.  Append  a	``+''  to
	      the  command  name to see any descriptions for the databases as well. If your Post-
	      greSQL installation was compiled with  multibyte	encoding  support,  the  encoding
	      scheme of each database is shown as well.

       \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.

	      Note: See the description of the LO_TRANSACTION variable for important  information
	      concerning all large object operations.

       \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.

	      Note:  See the description of the LO_TRANSACTION variable for important information
	      concerning all large object operations.

	      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.

	      Note:  See the description of the LO_TRANSACTION variable for important information
	      concerning all large object operations.

       \o [ {filename | |command} ]
	      Saves future query results to the file filename or pipes future results into a sep-
	      arate  Unix shell to execute command. If no arguments are specified, the query out-
	      put will be reset to stdout.

	      ``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, or latex. Unique
		     abbreviations are allowed.  (That would mean one letter is enough.)

		     ``Unaligned'' writes all fields of a tuple on a line, separated by the  cur-
		     rently  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-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.)

	      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 partic-
		     ular  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.

	      expanded (or x)
		     Toggles  between  regular	and  expanded  format.	When  expanded	format is
		     enabled, all output has two columns with the field 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 modes.

	      null   The second argument is a string that should be printed whenever a	field  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

		     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 ``pipe'' symbol).

	      footer Toggles the display of the default footer (x rows).

		     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 display 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

		     Note:  This  formerly only affected HTML mode. You can now set titles in any
		     output format.

	      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

	      pager  Toggles  the  use of a pager for query and psql help output. If the environ-
		     ment variable PAGER is set, the output is piped to  the  specified  program.
		     Otherwise a platform-dependent default (such as more) is used.

		     In  any  case,  psql only uses the pager if it seems appropriate. That means
		     among other things that the output is to a terminal and that the table would
		     normally  not fit on the screen. Because of the modular nature of the print-
		     ing routines it is not always possible to predict the number of  lines  that
		     will  actually  be  printed. For that reason psql might not appear very dis-
		     criminating about when to use the pager.

       Illustrations on how these different formats look can be seen in  the  Examples	[psql(1)]

	      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     Quit the psql program.

       \qecho text [ ... ]
	      This command is identical to \echo except that all 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 history library.

	      Note:  In  the  current version, it is no longer necessary to save the command his-
	      tory, 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 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 the sec-
	      tion about psql variables for details.

	      Although you are welcome to set any variable to anything you want, psql treats sev-
	      eral variables as special. They are documented 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 com-
	      mand is equivalent to \pset tuples_only and is provided for convenience.

       \T table_options
	      Allows you to specify options to be placed within the table  tag	in  HTML  tabular
	      output mode. This command is equivalent to \pset tableattr table_options.

	      Toggles a display of how long each SQL statement takes, in milliseconds.

       \w {filename | |command}
	      Outputs  the current query buffer to the file filename or pipes it to the Unix com-
	      mand command.

       \x     Toggles extended row format mode. As such it is equivalent to \pset expanded.

       \z [ pattern ]
	      Produces a list of all available tables with their associated  access  permissions.
	      If a pattern is specified, only tables whose name matches the pattern are listed.

	      The  commands  grant(7)  and  revoke(7)  are  used  to  set access permissions. See
	      grant(7) for more information.

	      This is an alias for \dp (``display permissions'').

       \! [ command ]
	      Escapes to a separate Unix shell or executes the Unix command  command.  The  argu-
	      ments are not further interpreted, the shell will see them as is.

       \?     Get help information about the backslash (``\'') commands.

       The  various  \d  commands  accept a pattern parameter to specify the object name(s) to be
       displayed. Patterns are interpreted similarly to SQL identifiers, in that 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.

       More interestingly, \d patterns allow the use of * to mean ``any sequence of characters'',
       and  ?  to mean ``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 *.*.

       psql  provides  variable substitution features similar to common Unix command shells. This
       feature is new and not very sophisticated, yet, but there are plans to expand  it  in  the
       future.	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

	      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  use-
	      ful  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 simply set, but has no  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 regular 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 convention, all specially  treated	variables
       consist	of all upper-case letters (and possibly numbers and underscores). To ensure maxi-
       mum compatibility in the future, avoid such variables. A list  of  all  specially  treated
       variables follows.

       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 or from a script are written to  the  standard
	      output before they are parsed or executed. To specify this on program start-up, use
	      the switch -a. If set to ``queries'', psql merely prints all queries  as	they  are
	      sent to the backend. The option for this is -e.

	      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. If you set the variable to the value noexec,
	      the queries are just shown but are not actually sent to the backend and executed.

	      The current client multibyte encoding. If you are not set up to use multibyte char-
	      acters, this variable will always contain ``SQL_ASCII''.

	      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.

	      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.

	      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 char-
	      acters 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.

	      The  value  of  the last affected OID, as returned from an INSERT or lo_insert com-
	      mand. This variable is only guaranteed to be valid until after the  result  of  the
	      next SQL command has been displayed.

	      If  you use the PostgreSQL large object interface to specially store data that does
	      not fit into one tuple, all the operations  must	be  contained  in  a  transaction
	      block.  (See the documentation of the large object interface for more information.)
	      Since psql has no way to tell if you already have a transaction  in  progress  when
	      you  call one of its internal commands (\lo_export, \lo_import, \lo_unlink) it must
	      take some arbitrary action. This action could either be to roll back  any  transac-
	      tion that might already be in progress, or to commit any such transaction, or to do
	      nothing at all. In the last case you must provide your own BEGIN TRANSACTION/COMMIT
	      block  or  the  results  will  be  unpredictable	(usually resulting in the desired
	      action's not being performed in any case).

	      To choose what you want to do you set this variable to one of ``rollback'',  ``com-
	      mit'',  or  ``nothing''.	The  default is to roll back the transaction. If you just
	      want to load one or a few objects this is fine. However, if you intend to  transfer
	      many large objects, it might be advisable to provide one explicit transaction block
	      around all commands.

	      By default, if non-interactive scripts encounter an error, such as a malformed  SQL
	      query 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
	      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).

       PORT   The database server port to which you are currently connected.  This is  set  every
	      time you connect to a database (including program start-up), but can be unset.



	      These specify what the prompt psql issues is supposed to 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.

	      This  variable  is  set by the command line option -S. You can unset or reset it at
	      run time.

	      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  con-
	      nect to a database (including program start-up), but can be unset.

       An  additional  useful  feature	of  psql variables is that you can substitute (``interpo-
       late'') 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 enti-

       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 field. 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 contain single quotes.
       These need to be escaped so that they don't cause a syntax error when the  third  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)! You can resolve it 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 com-
       mands 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 queries, the following rule applies: If the variable is
       not  set, the character sequence ``colon+name'' is not changed. In any case you can escape
       a colon with a backslash to protect it from interpretation. (The colon  syntax  for  vari-
       ables  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.)

       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 query. Prompt 2 is issued when more input is expected during query input because the
       query 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 tuples on the termi-

       The value of the respective prompt variable is printed literally, except where  a  percent
       sign  (``%'') is encountered.  Depending on the next character, certain other text is sub-
       stituted 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 compiled in default location.

       %m     The host name of the database server, truncated after 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 user name you are connected as (not your local system user name).

       %/     The name of the current database.

       %~     Like %/, but the output is ``~'' (tilde) if the database is your default database.

       %#     If the current user is a database superuser, then a ``#'', otherwise a ``>''.

       %R     In prompt 1 normally ``='', but ``^'' if in single-line mode, and ``!'' if the ses-
	      sion is disconnected from the database (which can happen	if  \connect  fails).  In
	      prompt  2  the  sequence	is  replaced by ``-'', ``*'', a single quote, or a double
	      quote, depending on whether psql expects more input because the query wasn't termi-
	      nated  yet, because you are inside a /* ... */ comment, or because you are inside a
	      quote. In prompt 3 the sequence doesn't resolve to anything.

	      If digits starts with 0x the rest of the characters are interpreted as a	hexadeci-
	      mal  digit  and  the  character  with the corresponding code is substituted. If the
	      first digit is 0 the characters are interpreted as on octal number and  the  corre-
	      sponding character is substituted. Otherwise a decimal number is assumed.

	      The  value  of the psql, variable name. See the section ``Variables [psql(1)]'' for

	      The output of command, similar to ordinary ``back-tick'' substitution.

       To insert a percent sign into your prompt, write %%. The default prompts are equivalent to
       '%/%R%# ' for prompts 1 and 2, and '>> ' for prompt 3.

	      Note: This feature was shamelessly plagiarized from tcsh.

       psql  supports the Readline library for convenient line editing and retrieval. The command
       history is stored in a file named .psql_history in your home  directory	and  is  reloaded
       when psql starts up. Tab-completion is also supported, although the completion logic makes
       no claim to be an SQL parser. When available, psql is automatically  built  to  use  these
       features.  If  for  some reason you do not like the tab completion, you can turn if off by
       putting this in a file named .inputrc in your home directory:

       $if psql
       set disable-completion on

       (This is not a psql but a readline feature. Read its documentation for further details.)

       HOME   Directory for initialization file (.psqlrc) and command  history	file  (.psql_his-

       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 disabled by using the \pset command.

	      Default database to connect to



       PGUSER Default connection parameters



       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.

       o Before  starting  up,	psql  attempts	to  read  and  execute	commands  from	the  file
	 $HOME/.psqlrc.  It  could be used to set up the client or the server to taste (using the
	 \set and SET commands).

       o The command-line history is stored in the file $HOME/.psql_history.

       o In an earlier life psql allowed the first argument of a single-letter backslash  command
	 to  start  directly after the command, without intervening whitespace. For compatibility
	 this is still supported to some extent, but I am 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.

       o psql only works smoothly with servers of the same version. That does not mean other com-
	 binations will fail outright, but subtle and not-so-subtle problems might come up. Back-
	 slash commands are particularly likely to fail if the server is of a different version.

       o Pressing  Control-C during a ``copy in'' (data sent to the server) doesn't show the most
	 ideal of behaviors. If you get a  message  such  as  ``COPY  state  must  be  terminated
	 first'', simply reset the connection by entering \c - -.

	      Note: This section only shows a few examples specific to psql. If you want to learn
	      SQL or get familiar with PostgreSQL, you might wish to read the  Tutorial  that  is
	      included in the distribution.

       The  first  example  shows  how	to spread a query 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-> );

       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    |

       At this point you decide to 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 make this table look differently 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;

       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

Application				    2002-11-22					  PSQL(1)

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