#include        <unistd.h>
#include        <fcntl.h>
#include        <stdio.h>

main()
{
        int fd, fdr, l1, l2, wb1, wb2;
        char buf [25];

        fd = open( "f1", O_WRONLY);
        fdr = open ("f1", O_RDONLY );
        l1 =lseek ( fd, -3, SEEK_END);
        printf("\nlseek returns %d-->\n",l1);
        wb1 = write(fd, "wxyz", 4);
        //printf("\nlseek2 --> %d\n", lseek(fd,-3,SEEK_END)+4);
        l2 = lseek(fd,4 , SEEK_SET );
        printf("\nlseek returns %d-->\n",l2);
        write(fd, "12",2);

        lseek ( fdr, 0, SEEK_SET );
        wb2 = read (fdr, buf, 20);
        write (1,buf, wb2);
}