PHP problem needs PHP experts

Question

Hey guys, I have a task to make a php script that takes txt file on INPUT and return another modified file on OUTPUT.

It's a terminal script(command line).

It's like syntax analysis in scanner of a compiler.
I have to go through chars 1 by 1 and detect macros (regex) and replace them....

Question1:
I used fgetc() but I need white spaces... how can I solve it?

Question2:
How to effectively use regex in php? (smth more than IF web)

Answer 1

Question3:
Where in PHP can I build structures? I need to store every macro(@macro_name) in a list or tree.

Question4:
How to manage command line arguments in php? I mean, I want to implement:
$ script_name -controller ; where controller changes behavior of the script.