#include <unistd.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdio.h>

int main()
{
  char block[1024];
  int in,out;
  in = open("file1",O_RDONLY);
  out = open("file8",O_WRONLY|O_CREAT,S_IRUSR|S_IWUSR);
  char buf[1024];

  int bytes_to_read;
 
    for (;bytes_to_read;)     // 这里和 for(;;) 和 while(1) 没有区别吗？
    {
        int read_chunk = bytes_to_read > sizeof(buf) ? sizeof(buf) : bytes_to_read;
        int bytes_read = read(in, buf, read_chunk);
        printf("%d\n",read_chunk);
        printf("%d\n",bytes_read);

        if (bytes_to_read < 0)
        {
            printf("Error reading context.\n");
        }
        printf("Test%d\n",read_chunk);
        printf("Test%d\n",bytes_read);
        bytes_to_read -= read_chunk;
    }
  exit(0);
}