#include <stdio.h>                              /* interleavingRead1.c */
#include <unistd.h>
#include <fcntl.h>
#include <sys/types.h>
#include <errno.h>
int main(void) { pid_t childpid; int i,k,n,fd; char buf[2];

   if ((childpid = fork()) == -1) { perror("fork"); return 1; }
   if ((fd = open("test",O_RDONLY)) == -1)
     { perror("couldn't open"); return 1; }

   k =  (childpid == 0) ? 1 : 10; /* distinguish parent and child */
   for (i=0; i<10; i++) {
     while((n = read(fd, buf, 1)) == -1 && (errno == EINTR)) {}
     printf("%2d: %2d --- %c\n", k, k * i, buf[0]);
     usleep((10 + k) * 20000);                                         }
   return 0; }