![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496404851416-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496404859181-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496405043724-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496405055228-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496408777578-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496408920574-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496408958176-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496449542957-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496449549881-wm) vim msgrcv.c ![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496449600089-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496449614583-wm) vim msgsnd.c ![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496449655206-wm)![实验楼](https://dn-simplecloud.shiyanlou.com/4230401496449665370-wm) fifo_write.c代码及注释如下 ``` #include #include #include #include #include #include #include #define MYFIFO "/tmp/myfifo" /* 有名管道文件名*/ #define MAX_BUFFER_SIZE PIPE_BUF /*定义在于 limits.h 中*/ int main(int argc, char * argv[]) /*参数为即将写入的字符串*/ { int fd; char buff[MAX_BUFFER_SIZE]; int nwrite; if(argc <= 1) { printf("Usage: ./fifo_write string\n"); exit(1); } sscanf(argv[1], "%s", buff); /* 以只写阻塞方式打开 FIFO 管道 */ fd = open(MYFIFO, O_WRONLY); if (fd == -1) { printf("Open fifo file error\n"); exit(1); } /*向管道中写入字符串*/ if ((nwrite = write(fd, buff, MAX_BUFFER_SIZE)) > 0) { printf("Write '%s' to FIFO\n", buff); } close(fd); exit(0); } ``` fifo_read.c代码及注释如下 ``` #include #include #include #include #include #include #include #include #define MYFIFO "/tmp/myfifo" /* 有名管道文件名*/ #define MAX_BUFFER_SIZE PIPE_BUF /*定义在于 limits.h 中*/ int main() { char buff[MAX_BUFFER_SIZE]; int fd; int nread; /* 判断有名管道是否已存在，若尚未创建，则以相应的权限创建*/ if (access(MYFIFO, F_OK) == -1) { if ((mkfifo(MYFIFO, 0666) < 0) && (errno != EEXIST)) { printf("Cannot create fifo file\n"); exit(1); } } /* 以只读阻塞方式打开有名管道 */ fd = open(MYFIFO, O_RDONLY); if (fd == -1) { printf("Open fifo file error\n"); exit(1); } while (1) { memset(buff, 0, sizeof(buff)); if ((nread = read(fd, buff, MAX_BUFFER_SIZE)) > 0) { printf("Read '%s' from FIFO\n", buff); } } close(fd); exit(0); } ``` vim msgsnd.c代码及注释 ``` #include #include #include #include #include #include #include #define BUFFER_SIZE 512 struct message { long msg_type; char msg_text[BUFFER_SIZE]; }; int main() { int qid; key_t key; struct message msg; /*根据不同的路径和关键字产生标准的 key*/ if ((key = ftok(".", 'a')) == -1) { perror("ftok"); exit(1); } /*创建消息队列*/ if ((qid = msgget(key, IPC_CREAT|0666)) == -1) { perror("msgget"); exit(1); } printf("Open queue %d\n",qid); while(1) { printf("Enter some message to the queue:"); if ((fgets(msg.msg_text, BUFFER_SIZE, stdin)) == NULL) { puts("no message"); exit(1); } msg.msg_type = getpid(); /*添加消息到消息队列*/ if ((msgsnd(qid, &msg, strlen(msg.msg_text), 0)) < 0) { perror("message posted"); exit(1); } if (strncmp(msg.msg_text, "quit", 4) == 0) { break; } } exit(0); } ``` vim msgrcv.c注释及程序 ``` ```

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