#include <fcntl.h>
main()
{
int fd1,fd2,fd3;
char buf[20];
open("fff",O_CREAT|O_TRUNC|O_RDWR,0777);
	fd1=open("fff",O_RDONLY);
		fd2=open("fff",O_WRONLY);
			fd3=open("fff",O_RDWR);
			write(fd3,"hello",5);
		write(fd2,"worlds",6);
	read(fd1,buf,6);
	write(1,buf,6);
                close(fd2);
			write(fd3,"oops",4);
	read(fd1,buf,6);
	write(1,buf,6);
}