有P1,P2,P3三个进程,利用Linux的通信机制实现字符串的分发:P1负责从键盘接收字符串,如果字符串的长度为偶数,则P1将字符串分发给P2,P2显示”P2 received *** from P1" ;如果字符串的长度为奇数,则P1将字符串分发给P3,P3显示”P3 received *** from P1" ;