Readings

Apache docs to build mods:

https://httpd.apache.org/docs/2.4/developer/modguide.html

https://httpd.apache.org/docs/trunk/programs/apxs.html

https://www.freepascal.org/~michael/articles/apache/apache.pdf

http://chriswu.me/blog/writing-hello-world-in-fcgi-with-c-plus-plus/

Outdated but interesting reading:

http://www.kaiyuanba.cn/content/develop/Perl/Writing_Apache_Modules_with_Perl_and_C.pdf