The file .pgpass in a user's home directory can
   contain passwords to
   be used if the connection requires a password (and no password has been
   specified  otherwise). On Microsoft Windows the file is named
   %APPDATA%\postgresql\pgpass.conf (where
   %APPDATA% refers to the Application Data subdirectory in
   the user's profile).
   Alternatively, a password file can be specified
   using the connection parameter passfile
   or the environment variable PGPASSFILE.
  
This file should contain lines of the following format:
hostname:port:database:username:password
   (You can add a reminder comment to the file by copying the line above and
   preceding it with #.)
   Each of the first four fields can be a literal value, or
   *, which matches anything.  The password field from
   the first line that matches the current connection parameters will be
   used.  (Therefore, put more-specific entries first when you are using
   wildcards.) If an entry needs to contain : or
   \, escape this character with \.
   The host name field is matched to the host connection
   parameter if that is specified, otherwise to
   the hostaddr parameter if that is specified; if neither
   are given then the host name localhost is searched for.
   The host name localhost is also searched for when
   the connection is a Unix-domain socket connection and
   the host parameter
   matches libpq's default socket directory path.
   In a standby server, a database field of replication
   matches streaming replication connections made to the master server.
   The database field is of limited usefulness otherwise, because users have
   the same password for all databases in the same cluster.
  
   On Unix systems, the permissions on a password file must
   disallow any access to world or group; achieve this by a command such as
   chmod 0600 ~/.pgpass.  If the permissions are less
   strict than this, the file will be ignored.  On Microsoft Windows, it
   is assumed that the file is stored in a directory that is secure, so
   no special permissions check is made.