UNIX for Dummies Questions & Answers

Hello everyone,
this question is probably simple for you ppl but i am jus a beginner and still learing. i was wondering if someone could tell me that how does unix identify different program codes in it's environment.
for example, unix recognises this C code in the body of any script. how does that work? or for instance if it was something written in perl, it would be supported!?

#include <stdio.h>
FILE *popen(const char *command, const char *open_mode);
int pclose(FILE *stream_to_close);

Can someone please help me on that!?
Thank You!

What do you mean exactly?

Are you curious as to why some programs, like text editors manage to identify which programming language a piece of code represents? File extension, or even existence of certain keywords particular to a language can help identify the programming language used with a bit of parsing. After all, these are all heuristic methods that practically works quite well with sometimes quite accurate guesses but they are not necessarily correct.

I don't think Unix by itself recognizes the language used. For example, if you want to compile a C program you need to explicitly invoke 'cc'; while for a Perl program you need to invoke 'perl' (or as the top shebang line). There is no mystery in there.

Excuse me??!!! Recognition of c code is not mandated by Posix for any interpreter.

csh
tcsh
sh
ksh
bash

are a few shells that can do no such thing.