An administrator is generally a person who is
  in charge of installing and running the server.  A user
  could be anyone who is using, or wants to use, any part of the
  PostgreSQL system.  These terms should not
  be interpreted too narrowly; this documentation set does not have fixed
  presumptions about system administration procedures.
 
  We use /usr/local/pgsql/ as the root
  directory of the installation and /usr/local/pgsql/data
  as the directory with the database files.  These directories may vary
  on your site, details can be derived in the Administrator's Guide.
 
  In a command synopsis, brackets
  ([ and ]) indicate an optional phrase or keyword.
  Anything in braces
  ({ and }) and containing vertical bars
  (|)
  indicates that you must choose one alternative.
 
  Examples will show commands executed from various accounts and programs.
  Commands executed from a Unix shell may be preceded with a dollar sign
  ("$").  Commands executed from particular user
  accounts such as root or postgres are specially flagged and explained.
  SQL commands may be preceded with
  "=>"
  or will have no leading prompt, depending on the context.
 
Note:    The notation for
   flagging commands is not universally consistent throughout the
   documentation set.
   Please report problems to the documentation mailing list
   <pgsql-docs@postgresql.org>.