When a program runs in a text based environment like command

When a program runs in a text based environment like command line interface, what determine the order in which things happen?

Solution

It is the program itself (I.e the instructions) that determine how the order in which things happen.

The program that contains many subprogram to which it makes calls .Subprogram routine modules are substituted in the form of assembly language codes which are manipulated as machine language codes.