lab 1

int father[2]，son[2];
int son[2];

if (fork() == 0) {
    int n;
    char buf[1];

    close(0);
    dup(father[1]);
    close(1);
    dup(son[0]);
    
    for(;;) {
        read(0,buf,n);
        write(1,buf,1);
    }
    
    
} else {
    int n ;
    char buf[1] = 'c';

    close(1);
    dup(father[0]);
    close(0);
    dup(son[1]);

    for{ ;; }{
        write(1,buf,1);
        read(0,buf,n)    ;
    }