Whenever we type in a command of AIX, how does it get interpreted by AIX?(backend processing)
The little man in AIX, you can see him in smit if you have a LFT or GUI interface, jots down your command on a piece of paper, then he goes to the library (/lib directories) and looks up what to do for your command, you can see what he is looking up in the manual pages.
When he has found what you want him to do he then looks up where he needs to go next, you will not see this in the manual pages because it is secret.
He might go and get some data from a disk, or he might ask one of his special little friends to call up another system over the network.
It all depends on what commands you use really.
why would you like to know How AIX processes this command unless you are a Hardware or O/S programmer ? and if you were you wouldn't have asked this question 
search google: commands UNIX operating level compile - Google Search