A程序代码：

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
int main(int argc, const char *argv[])
{if(mkfifo("./fifo1",0664)<0){if(errno !=17){perror("mkfifo");return -1;}}if(mkfifo("./fifo2",0664)<0){if(errno !=17){perror("mkfifo");return -1;}}printf("mkfifo success\n");int fd1 = open("./fifo1",O_WRONLY);if(fd1<0){perror("open");return -1;}int fd2=open("./fifo2",O_RDONLY);if(fd2<0){perror("open_fifo2");return-1;}printf("open RDONLY NONBLOCK success\n");char buf[128];ssize_t res;while(1){printf("输入数据>>\n");fgets(buf,sizeof(buf),stdin);buf[strlen(buf)-1]='\0';if(write(fd1,buf,sizeof(buf))<0){perror("write");return -1;}printf("写入成功\n");if(strcmp(buf,"quit")==0){break;                                                                              }
//读数据ibzero(buf,sizeof(buf));res=read(fd2,buf,sizeof(buf));if(res<0){perror("read");return -1;}else if(res==0){printf("写端关闭，且管道没有数据");break;}printf("fd2:%ld  %s\n",res,buf);}close(fd2);close(fd1);return 0;
}

B程序代码：

#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
int main(int argc, const char *argv[])
{if(mkfifo("./fifo1",0664)<0){if(errno !=17){perror("mkfifo");return -1;}}if(mkfifo("./fifo2",0664)<0){if(errno !=17){perror("mkfifo");return -1;}}printf("mkfifo success\n");pid_t pid;int fd1 = open("./fifo1",O_RDONLY);if(fd1<0){perror("open");return -1;}int fd2 = open("./fifo2",O_WRONLY);if(fd2<0){perror("open");return -1;}printf("open RDONLY NONBLOCK success\n");char buf[128];ssize_t res;while(1){bzero(buf,sizeof(buf));res=read(fd1,buf,sizeof(buf));if(res<0){perror("read");return -1;}else if(0==res){                                                                       printf("写端关闭,且管道里没有数据\n");break;}printf("%ld :%s \n",res,buf);//写数据bzero(buf,sizeof(buf));printf("输入数据>>\n");fgets(buf,sizeof(buf),stdin);buf[strlen(buf)-1]='\0';if(write(fd2,buf,sizeof(buf))<0){perror("write");return -1;}printf("fd2_写入成功\n");if(strcmp(buf,"quit")==0){break;}}close(fd2);close(fd1);return 0;
}

运行结果：