PostgreSQL Contents
psql - run the interactive query front-end
psql [-a authsvc
] [-A ] [-c query ] [-d dbName] [-e ] [-f filename] [-F separator] [-h hostname]
[-H ] [-l ] [-n ] [-o filename ] [-p port] [-q ] [-s ] [-S ] [-t ] [-T table-options
] [-u ] [-x ] [dbname]
psql is a interactive query front-end
to Postgres. It enables you to type in queries interactively, issue them
to Postgres, and see the query results. psql can be used in a pipe sequence,
and automatically detects when it is not listening or talking to a real
tty. psql is designed to be an enhanced version of the older monitor program.
psql is a frontend application, like any other. Hence, a postmaster process
must be running on the database server host before psql is executed. In
addition, the correct postmaster port number must be specified as described
below.
The optional argument dbname specifies the name of the database
to be accessed. This database must already have been created. dbname defaults
to the value of the USER
environment variable or, if that's not set, to
the Unix account name of the current user.
When psql starts, it reads SQL
commands from /etc/psqlrc and then from $(HOME)/.psqlrc This allows SQL
commands like SET which can be used to set the date style to be run at
the start of evry session.
psql understands the following command-line options:
- -a system
- Specifies an authentication system system (see pgintro(1)
) to
use in connecting to the postmaster process. This option no longer has
any effect.
- -A
- Turn off fill justification when printing out table elements.
- -c query
- Specifies that psql is to execute one query string, query, and
then exit. This is useful for shell scripts, typically in conjunction
with the -q options. -c option in shell scripts.
- -d dbName
- Specifies the name
of the database to connect to.
- -e
- Echo the query sent to the backend
- -f
filename
- Use the file filename as the source of queries instead of reading
queries interactively.
- -F separator
- Use separator as the field separator.
The default is "|".
- -h hostname
- Specifies the hostname of the machine on
which the postmaster is running. Without this option, communication is
performed using local Unix domain sockets.
- -H
- Turns on HTML3.0
tabular output.
- -l
- Lists all available databases
- -n
- Do not use the readline library for
input line editing and command history.
- -o filename
- Put all output into
filename
- -p port
- Specifies the TCP/IP port or local Unix domain socket
file extension on which the postmaster is listening for connections. Defaults
to 5432, or the value of the PGPORT
environment variable (if set).
- -q
- Specifies
that psql should do its work quietly. By default, it prints welcome and
exit messages and prompts for each query, and prints out the number of
rows returned from a query. If this option is used, none of this happens.
This is useful with the -c option in shell scripts.
- -s
- Run in single-step
mode where the user at prompted for each query before it is sent to the
backend.
- -S
- Run ins single-line mode where each query is terminated by a
newline, instead of a semicolon.
- -t
- Turn off printing of column names. This
is useful with the -c option in shell scripts.
- -T table-options
- Allows you
to specify options to be placed within the <table ...> tag for HTML3.0
tabular
output. For example border will give you tables with borders.
- -u
- Asks the
user for the user name and password before connecting to the database.
If the database does not require password authentication then these are
ignored. If the option i snot used (and the PGPASSWORD environment variable
is not set) and the database requires password authentication, then the
connection will fail. The user name is ignored anyway.
- -x
- Turns on extended
row format mode. When enabled each row will have its column names printed
on the left with the column values printed on the right. This is useful
for rows which are otherwise too long to fit into one screen line. HTML
row output supports this mode also.
You may set environment variables to
avoid typing some of the above options. See the "ENVIRONMENT VARIABLES"
section below.
psql attempts to make a connection
to the database at the hostname and port number specified on the command
line. If the connection could not be made for any reason (e.g. insufficient
privileges, postmaster is not running on the server, etc) psql will return
an error that says Connection to database failed.
The reason for the connection
failure is not provided.
In normal operation, psql provides
a prompt with the name of the database that psql is current connected
to followed by the string "=>". For example, Welcome to the POSTGRESQL interactive
sql monitor:
Please read the file COPYRIGHT for copyright terms of
POSTGRESQL
type \? for help on slash commands
type \q to quit
type \g or terminate with semicolon to execute query
You are currently
connected to the database: testdb
testdb=>
At the prompt, the user may
type in SQL queries. Unless the -S option is set, input lines are sent
to the backend when a query-terminating semicolon is reached.
Whenever a
query is executed, psql also polls for asynchronous notification events
generated by listen(l)
and notify(l)
.
Anything you enter
in psql that begins with an unquoted backslash is a psql command. Anything
else is SQL and simply goes into the current query buffer (and once you
have at least one complete query, it gets automatically submitted to
the backend). Psql commands are also called slash 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 white space characters.
With single
character command verbs, you don't actually need to separate the command
verb from the argument with white space, for historical reasons. You should
anyway.
- \a
- Toggle field alignment when printing out table elements.
- \C caption
- Set the HTML3.0 table caption.
- \connect dbname username
- Establish a connection
to a new database. The previous connection is closed.
- \copy table {FROM
| TO} filename
- Perform a frontend copy. This is an operation that runs
a SQL COPY command, but instead of the backend reading or writing a specified
file, and consequently requiring special user privilege, psql reads or
writes the file and routes the data to or from the backend.
- \d [table ]
- List tables in the database, or if table is specified, list the columns
in table. If table name is *, list all tables and column information for
each tables.
- \da
- List aggregates.
- \dd object
- List the description of the table,
table.column, type, operator, or aggregate.
- \df
- List functions.
- \di
- List only
indexes.
- \do
- List operators.
- \ds
- List only sequences.
- \dS
- List system tables
and indexes.
- \dt
- List only tables.
- \dT
- List types.
- \e [filename ]
- Edit the current
query buffer or file .
- \E [filename ]
- Edit the current query buffer or file
and execute it upon editor exit.
- \f [separator ]
- Set the field separator.
Default is a single blank space.
- \g [|command ] | [filename ]
- Send the current
query input buffer to the backend and optionally save the output in filename
or pipe the output into |command.
- \h [command ]
- Give syntax help on the specified
SQL command. If the command is not specified, list all the commands for
which syntax help is available. If the command is *, give syntax help
on all SQL commands.
- \H
- Toggle html3 output.
- \i filename
- Read queries from
filename into the query input buffer.
- \l
- List all the databases in the server.
- \m
- Toggle monitor-like table display. This is standard SQL output (i.e extra
border characters).
- \o [|command ] | [filename ]
- Send query results to filename.
Or pipe into command. If no arguments are specified, send query results
to stdout.
- \p
- Print the current query buffer.
- \q
- Quit the psql program.
- \r
- Reset(clear)
the query buffer.
- \s [filename ]
- Print or save the command line history
to filename . (Only available if psql is configured to use readline)
- \t
- Toggle display of output column name headings and row count (defaults
to on).
- \T
- Set html3.0 <table ...> options.
- \x
- Toggles extended row format mode.
When enabled each row will have its column names printed on the left with
the column values printed on the right. This is useful for rows which are
otherwise too long to fit into one screen line. HTML row output mode supports
this flag too.
- \z
- Produces a list of all tables in database with their appropriate
ACLs (grant/revoke permissions) listed.
- \! [command ]
- Escape to shell or
execute command.
- \?
- Get help information about the \ commands.
There are some environment variables which can be used in liu
of command line arguments; these are detailed below. Additionally, the
Postgres frontend library used by the psql application looks for other
optional environment variables to configure, for example, the style of
date/time representation and the local time zone. Refer to libpq(3)
for
more details.
You may set any of the following environment variables to
avoid specifying command-line options: hostname: PGHOST
port:
PGPORT
tty: PGTTY
options: PGOPTION
realm: PGREALM
Setting PGHOST to a non-zero-length string causes TCP/IP communication to
be used, rather than the default local Unix domain sockets.
If PGOPTION
is specified, then the options it contains are parsed before any command-line
options.
PGREALM
only applies if Kerberos authentication is in use. If
this environment variable is set, Postgres will attempt authentication
with servers for this realm and use separate ticket files to avoid conflicts
with local ticket files. See pgintro(1)
for additional information on Kerberos.
psql returns 0 to the shell on successful completion of
all queries, 1 for errors, 2 for abrupt disconnection from the backend.
psql will also return 1 if the connection to a database could not be made
for any reason.
libpq(3)
, monitor(1)
postgres(1)
, postmaster(1)
.
Table of Contents