进程间通信之消息队列

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key_t ftok( const char * fname, int id )

用于生成ID值

int msgget(key_t key, int msgflg);

通过key，获取消息队列权限或创建消息队列

int msgsnd(int msqid, const void *msgp, size_t msgsz, int msgflg);

size_t msgrcv(int msqid, void *msgp, size_t msgsz, long msgtyp, int msgflg);

发送接收消息函数

以下为创建发送消息的一段代码

#include <stdio.h>#include <sys/ipc.h>#include <sys/msg.h>#include <sys/types.h>struct msgbuf{    long type;    char text[256];};int main(){    key_t key;    int ret;    int qid;    struct msgbuf msg;    key = ftok(".", 'a');    printf("key is %d\n", key);   qid = msgget(key,IPC_CREAT|0666);    if(-1 == qid)    {        printf("msgget error\n");        return -1;    }    printf("qid is %d\n", qid);    msg.type = 100;    (void)strcpy(&msg.text, "hello");    ret = msgsnd(qid, &msg, sizeof(msg.text), msg.type);    if(ret < 0)    {        printf("msgsnd error\n");        return -1;    }    return 0;}

执行上面程序2次后

linux-o45o:~ # ipcs -q
------ Message Queues --------
key msqid owner perms used-bytes messages
0x61122012 0 root 666 512 2

#include <stdio.h>#include <sys/ipc.h>#include <sys/msg.h>#include <sys/types.h>struct msgbuf{    long type;    char text[256];};int main(){    key_t key;    int ret;    int qid;    struct msgbuf msg;    key = ftok(".", 'a');    printf("key is %d\n", key);    qid = msgget(key,IPC_CREAT|0666);    if(-1 == qid)    {        printf("msgget error\n");        return -1;    }    printf("qid is %d\n", qid);    msg.type = 100;    ret = msgrcv(qid, &msg, sizeof(msg.text), msg.type, 0);    if(ret < 0)    {        printf("msgrcv error\n");        return -1;    }    printf("msg is %s\n", msg.text);    return 0;}

执行程序1输出
key is 1628577810
qid is 0
执行程序2输出
key is 1628577810
qid is 0
msg is hello