/* This program illustrates the use of Unix/C file descriptors
   for Disk IO.  It copies up to 1k at a time.
*/

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

int main(int argc, char * argv[])
{  int i = 1024;
   int infd, outfd;
   unsigned char buffer[1024];
   if (argc != 3) exit(1);
   infd = open(argv[1],O_RDONLY,0);
   outfd = open(argv[2],O_WRONLY | O_CREAT | O_TRUNC,0755);
   // above line same as outfd = creat(argv[2],0755)
   while (i==1024) 
     {
       i = read(infd,buffer,1024); // read up to 1024 bytes;
       if (i>0) write(outfd,buffer,i);
     }
   close(infd);
   close(outfd);   
   exit(0);
}