SAVE PREPROCESSOR OUTPUT

root@dev:~$ nano programName.c 
#include <stdio.h>
int main(void)
{
  printf("Hello World\n");
  return 0;
}

root@dev:~$ gcc -E programName.c -o programName.i

 * the -E option allows the programmer to save the outputs of the PREPROCESSOR!
    -   -E Preprocess only; do not compile, assemble or link.

root@dev:~$ ls
 programName.c programName.i
 
root@dev:~$ cat programName.i
 ## 1 "tiny_program.c"
 ## 1 "<built-in>"
 ## 1 "<command-line>"
 ## 31 "<command-line>"
 ## 1 "/usr/include/stdc-predef.h" 1 3 4
 ## 32 "<command-line>" 2
 ## 1 "tiny_program.c"
 ## 1 "/usr/include/stdio.h" 1 3 4
 ## 27 "/usr/include/stdio.h" 3 4
 ## 1 "/usr/include/x86_64-linux-gnu/bits/libc-header-start.h" 1 3 4
 ## 33 "/usr/include/x86_64-linux-gnu/bits/libc-header-start.h" 3 4
 ## 1 "/usr/include/features.h" 1 3 4
 ## 424 "/usr/include/features.h" 3 4
 ## 1 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 1 3 4
 ## 427 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 3 4
 ## 1 "/usr/include/x86_64-linux-gnu/bits/wordsize.h" 1 3 4
 ## 428 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 2 3 4
 ## 1 "/usr/include/x86_64-linux-gnu/bits/long-double.h" 1 3 4
 ## 429 "/usr/include/x86_64-linux-gnu/sys/cdefs.h" 2 3 4
 ## 425 "/usr/include/features.h" 2 3 4
 ## 448 "/usr/include/features.h" 3 4
 ## 1 "/usr/include/x86_64-linux-gnu/gnu/stubs.h" 1 3 4
 ## 10 "/usr/include/x86_64-linux-gnu/gnu/stubs.h" 3 4
 ## 1 "/usr/include/x86_64-linux-gnu/gnu/stubs-64.h" 1 3 4
 ## 11 "/usr/include/x86_64-linux-gnu/gnu/stubs.h" 2 3 4
 ## 449 "/usr/include/features.h" 2 3 4
 ## 34 "/usr/include/x86_64-linux-gnu/bits/libc-header-start.h" 2 3 4
 ## 28 "/usr/include/stdio.h" 2 3 4
 **** About 700 lines ****

extern void funlockfile (FILE*__stream) __attribute__((__nothrow__,__leaf__));
## 868 "/usr/include/stdio.h" 3 4
## 2 "tiny_program.c" 2
## 3 "tiny_program.c"
int main(void)
{
  printf("Hello World\n");
  return 0;
}

 * ONLY the last four lines are C source code; the rest are code included in the
   program by the preprocessor
    - all of these code are passed to the gcc compiler!