If you've got a database, Perl can work with it. This section describes some of the common types of databases. We've seen the DBI module briefly in Chapter 15.
B.7.1. Direct System Database Access
Perl can directly access some system databases, sometimes with the help of a module. These are databases like the Windows Registry (which holds machine-level settings), or the Unix password database (which lists which username corresponds to which number, and related information), as well as the domain-name database (which lets you translate an IP number into a machine name, and vice versa).
B.7.2. Flat-File Database Access
If you'd like to access your own flat-file databases from Perl, there are modules to help you do that (seemingly a new one every month or two, so any list here would be out of date).