To modify the prompt, use \set to change the strings held by the three prompt variables. When defining your prompt strings, use % to designate that you wish for a variable to be substituted into the string (read further for a list of defined substitutions you can make with the % sign). You may also use \n to display new line character. All other characters will be displayed normally. The following example adds a trivial amount of information into the PROMPT1 variable: the prompt will now display the prefix psql .
Example 4-60. Setting the Prompt Variables
testdb=# \set PROMPT1 'psql %/%R%' psql testdb=
Table 4-17. Defined % Substitution Strings
This will insert the name of the database you are currently working in; however, if you are currently working in the default database, a tilde ( ~ ) will be displayed.
This will insert a number sign (#) if the current user is defined as a superuser within the database. Otherwise, it will insert a greater-than sign ( > ).
This will insert the port number the database server is currently accepting connections at.
This will insert the name of the database you are currently working in.
This will insert the hostname of the server the database is currently running on, truncated down to the string before the first dot (i.e., "yourserver.com" would become "yourserver" when inserted).
This will insert the full hostname of the server the database is currently running on. If no hostname information is available, the string "localhost" will be inserted.
This will insert the database username you are currently connected as.
When used with PROMPT1, this will insert an equal sign (=) during normal operation; in single-line mode, it will insert a caret (^); and if your session ever becomes disconnected from the backend process, an exclamation point (!) is inserted. When used with PROMPT2, %R inserts a dash (-) instead of an equal sign during normal operation, and whatever you entered as the end-symbol if you started a new line during an unterminated statement (for example, if you leave a parenthesis open while entering a multi-line query, this variable will display a parenthesis in the prompt). Nothing is inserted if this is used with the PROMPT3 variable.
%[ number ]
You may enter decimal, octal, or hexidecimal numbers into the prompt variables. To specify whether the number you are entering is octal, prefix it with a 0; to specify the number is hexidecimal, prefix it with a 0x; otherwise it is interepreted as decimal number.
%:[ variable_name ]
To insert a psql variable, use the colon (:) and the variable's identifier.
%` command ]`
Inserts the output of whatever command is specified with the command parameter.