BASH has the ability to load compiled modules to create new commands which interface with the operating system more directly than can be achieved by calling external commands. These are called loadable builtins.

Loadable builtins must be compiled for your system, usually from within the bash source tree: 

 .../bash-3.2$ CC=whatever ./configure
 .../bash-3.2$ make
 .../bash-3.2$ exec ./bash
 .../bash-3.2$ cd examples/loadables/
 .../loadables$

The rest is going to require a machine with dlopen() apparently. :(