The file .pgpass in a user's home directory is a file that can contain passwords to be used if the connection requires a password (and no password has been specified otherwise). This file should have lines of the following format:
Each of the first four fields may 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 permissions on .pgpass must disallow any access to world or group; achieve this by the command chmod 0600 ~/.pgpass. If the permissions are less strict than this, the file will be ignored.