feauture.c

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>

int main (void) {

#ifdef _POSIX_SOURCE
  printf ("_POSIX_SOURCE defined\n");
#endif

#ifdef _POSIX_C_SOURCE
  printf ("_POSIX_C_SOURCE defined: %ldL\n", (long) _POSIX_C_SOURCE);
#endif

#ifdef _POSIX_SAVED_IDS
  printf("_POSIX_SAVED_IDS defined: %d\n", _POSIX_SAVED_IDS);
#endif

#ifdef _ISOC99_SOURCE
  printf ("_ISOC99_SOURCE defined\n");
#endif

#ifdef _XOPEN_SOURCE
  printf ("_XOPEN_SOURCE defined: %d\n", _XOPEN_SOURCE);
#endif

#ifdef _XOPEN_SOURCE_EXTENDED
  printf ("_XOPEN_SOURCE_EXTENDED defined\n");
#endif

#ifdef _LARGEFILE64_SOURCE
  printf ("_LARGEFILE64_SOURCE defined\n");
#endif

#ifdef _FILE_OFFSET_BITS
  printf ("_FILE_OFFSET_BITS defined: %d\n", _FILE_OFFSET_BITS);
#endif

#ifdef _BSD_SOURCE
  printf ("_BSD_SOURCE defined\n");
#endif

#ifdef _SVID_SOURCE
  printf ("_SVID_SOURCE defined\n");
#endif

#ifdef _ATFILE_SOURCE
  printf ("_ATFILE_SOURCE defined\n");
#endif

#ifdef _GNU_SOURCE
  printf ("_GNU_SOURCE defined\n");
#endif

#ifdef _REENTRANT
  printf ("_REENTRANT defined\n");
#endif

#ifdef _THREAD_SAFE
  printf ("_THREAD_SAFE defined\n");
#endif

#ifdef _FORTIFY_SOURCE
  printf ("_FORTIFY_SOURCE defined\n");
#endif

#ifdef _POSIX_JOB_CONTROL
  printf ("_POSIX_JOB_CONTROL defined: %d\n", _POSIX_JOB_CONTROL);
#endif
  
  exit(EXIT_SUCCESS);
}