一、要求实现AB进程对话

1. A进程先发送一句话给B进程，B进程接收后打印
2. B进程再回复一句话给A进程，A进程接收后打印
3. 重复1.2步骤，当收到quit后，要结束AB进程

A进程

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
int main(int argc, const char *argv[])
{if(mkfifo("./fifo_A",0664) < 0){if(errno != 17){perror("mkfifo");return -1;}}if(mkfifo("./fifo_B",0664) < 0){if(errno != 17){perror("mkfifo");return -1;}}int fd_A = open("./fifo_A",O_WRONLY);if(fd_A < 0){perror("open");return -1;}int fd_B = open("./fifo_B",O_RDONLY);if(fd_B < 0){perror("open");return -1;}printf("open success\n");char buf[128] = "";while(1){scanf("%s",buf);write(fd_A,buf,sizeof(buf));bzero(buf,sizeof(buf));read(fd_B,buf,sizeof(buf));if(strcmp(buf,"quit") == 0){write(fd_A,buf,sizeof(buf));break;}printf("%s\n",buf);}close(fd_A);close(fd_B);return 0;
}

B进程 

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <unistd.h>
#include <string.h>
int main(int argc, const char *argv[])
{if(mkfifo("./fifo_A",0664) < 0){if(errno != 17){perror("mkfifo");return -1;}}if(mkfifo("./fifo_B",0664) < 0){if(errno != 17){perror("mkfifo");return -1;}}int fd_A = open("./fifo_A",O_RDONLY);if(fd_A < 0){perror("open");return -1;}int fd_B = open("./fifo_B",O_WRONLY);if(fd_B < 0){perror("open");return -1;}printf("open success\n");char buf[128] = "";while(1){bzero(buf,sizeof(buf));read(fd_A,buf,sizeof(buf));if(strcmp(buf,"quit") == 0){write(fd_B,buf,sizeof(buf));break;}printf("%s\n",buf);scanf("%s",buf);write(fd_B,buf,sizeof(buf));}close(fd_A);close(fd_B);return 0;
}