gistfile1.c

#include <sys/types.h>  
#include <unistd.h>      
#include <fcntl.h>
#include <stdio.h>

int main() {
  int fd;
  struct flock lock, savelock;

  fd = open("fake.dat", O_RDWR);
  printf("fd = %d\n", fd);
  
  lock.l_type = F_WRLCK;
  lock.l_start = 0;
  lock.l_whence = SEEK_SET;
  lock.l_len = 0;

  savelock = lock;

  int code = fcntl(fd, F_GETLK, &lock);

  printf("fcntl return code: %d\n", code);

  exit(0);
}