Sendmail, 3rd Edition

Name

hash

Synopsis

The hash database-map type uses a hashing algorithm for storing data. This approach to a database is described in A New Hash Package for UNIX, by Margo Seltzer (Usenix Proceedings, Winter 1991). The hash type is available only if sendmail was compiled with NEWDB defined and the Berkeley or Sleepycat db(3) library linked.

The hash type is the default that is used with most of the features offered by the mc configuration technique (see Table 23-4 in Section 23.5). For example, consider the following:

Kuudomain hash -o /etc/mail/uudomain

Here, a database map named uudomain is declared to be of type hash. The -o says that the database file /etc/mail/uudomain is optional.

Quite a few other database-map switches are available with this type. The complete list is shown in Table 23-13.

Table 23-13. The hash database-map type K command switches

Switch	§	Description
-A	-A	Append values for duplicate keys
-a	-a	Append tag on successful match
-D	-D	Don’t use this database map if DeliveryMode=defer
-f	-f	Don’t fold keys to lowercase
-m	-m	Suppress replacement on match
-N	-N	Append a null byte to all keys
-O	-O	Never add a null byte
-o	-o	This database map is optional
-q	-q	Don’t strip quotes from key
-S	-S	Space replacement character
-T	-T	Suffix to append on temporary failure
-t	-t	Ignore temporary errors

The -d38.20 command-line switch (-d38.20) can be used to observe this type’s lookups in more detail. See also the btree type (btree