main() /* cat command; Kernighan, Ritchie, p. 180 */
{
 copyfile(0,1);
}

#define BLOCK 512

copyfile(fd1,fd2) 
int fd1, fd2;
{
 char buffer[BLOCK];
 int n;

 while ((n = read(fd1, buffer, BLOCK)) > 0)
  write(fd2, buffer, n);
}