The makemap (1) program (part of sendmail 's source) is useful for producing database files. It supports the ndbm (3) form of database, and the hash and btree forms of the Berkeley db (3) database (see §33.2).
makemapswitches class database
The
makemap
(1) program reads from its standard input lines of text with the key preceding the value on each line. Output is to
database
file. The
class
is selected from
dbm
,
btree
, or
hash
. The
switches
are:
Allows duplicate keys. Without this switch, duplicate keys cause warnings to be printed (see §33.2.1.1).
Prevents (the default) folding of keys from upper- to lowercase (see §33.2.1.2).
Appends a null byte to all keys (see §33.2.1.3).
Prevents file from being truncated on open (2). In other words, append to, don't overwrite the file (see §33.2.1.4).
Replaces (silently) a duplicate key's value with the new value (see §33.2.1.5).
Sets verbose mode so that you can watch keys and data being added (see §33.2.1.6).