In this section we will create the same "Hello World" module using the C API. This will show you how closely related the two APIs really are. Many of the details in this section are specific for Unix versions of Apache. For differences relating to working in Win32 environments, be sure to read the section Section 2.5.3.
The preparation for writing C API modules is somewhat simpler than that for the Perl modules. You just need to create a subdirectory in the Apache source tree to hold your site-specific source code. We recommend creating a directory named site in the modules subdirectory. The complete path to the directory will be something like ~www/src/modules/site (C:\Apache\src\modules\site on Win32 systems).
To have this new subdirectory participate in the server build process, create a file within it named Makefile.tmpl. For simple modules that are contained within a single source file, Makefile.tmpl can be completely empty. The Apache configure script does a pretty good job of creating a reasonable default makefile. Makefile.tmpl is there to provide additional file and library dependencies that Apache doesn't know about.
The next step is to create the module itself. Example 2.2 shows the source for mod_hello. Create a file in the site subdirectory named mod_hello.c and type in the source code (or better yet, steal it from the source code listings in http://www.modperl.com/book/source/).