pg_passwd is a tool to manipulate a flat text password file for the purpose of using that file to control client authentication of the PostgreSQL server. More information about setting up this authentication mechanism can be found in the Administrator's Guide.
The form of a text password file is one entry per line; the fields of each entry are separated by colons. The first field is the user name, the second field is the encrypted password. Other fields are ignored (to allow password files to be shared between applications that use similar formats). The functionality of the pg_passwd utility is to enable a user to interactively add entries to such a file, to alter passwords of existing entries, and to take care of encrypting the passwords.
Supply the name of the password file as argument to the pg_passwd command. To be of use for client authentication the file needs to be located in the server's data directory, and the base name of the file needs to be specified in the pg_hba.conf access control file.
$ pg_passwd /usr/local/pgsql/data/passwords File "/usr/local/pgsql/data/passwords" does not exist. Create? (y/n): y Username: guest Password: Re-enter password:where the Password: and Re-enter password: prompts require the same password input which is not displayed on the terminal. Note that the password is limited to eight useful characters by restrictions of the standard crypt(3) library routine.
The original password file is renamed to passwords.bk.
To make use of this password file, put a line like the following in pg_hba.conf:
host mydb 184.108.40.206 255.255.255.255 password passwordswhich would allow access to database mydb from host 220.127.116.11 using the passwords listed in the passwords file (and only to the users listed in that file).
Note: It is also useful to have entries in a password file with an empty password field. (This is different from an empty password.) These entries cannot be managed by pg_passwd, but it is always possible to edit password files manually.