Configuration files are placed in / etc by most software developers, and this is standard practice for Debian packages. If the file is fairly simple, and the only file required, it is often placed directly in / etc with a .conf extension, such as / etc/ inetd. conf for the openbsd-inetd package. For packages that require a more complex configuration, usually via multiple configuration files, those files are placed in a subdirectory of /etc which is generally named after the package. A good example of this is the apache2 package, which has its configuration files in / etc/ apache2 and its subdirectories.
Multiple files in a subdirectory are used for a number of reasons. In some cases, it is because the original software uses different files for different purposes. In other cases, it is done to organize configuration items into a more manageable and understandable group. Occasionally, Debian developers have modified the package to organize the configuration to simplify or streamline administration.
A good example of this is Apache. Normal Apache configuration is either by a single file or multiple files that are included by the master configuration file. Traditionally, SSL (Secure Sockets Layer) certificates and keys, and Virtual Host configuration files are contained in a subdirectory, but all major options are configured in one or a few files in the main directory. Debian has actually split the configuration into many files in various subdirectories. This allows Debian to supply separate packages that provide certain features via individual configuration files that are added to the proper directory, rather than requiring modification of the primary configuration files. Also, there are subdirectories for modules and virtual hosts prefixed by available-or enabled-. This allows a simple script to activate or deactivate modules and virtual hosts easily and quickly.
As it's not yet available in the stable release, Debian developers are taking < this concept further in future releases, by providing a config-available and config-enabled directory, as well as allowing features to be activated and deactivated without editing config files or installing or removing feature packages. This will probably be available in Debian 8, code-named Jessie.
