接受消息队列

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <errno.h>
#include <string.h>

typedef struct
{
long int nType;
char szText[256];
}MSG;

int main(int argc, char** argv) {
    key_t IKey1;
    int n,nMsgId;
    MSG msg;
    if((IKey1 = ftok("/etc/profile",1)) == -1)
    {
        perror("ftok");
        exit(1);
    }
    
    if((nMsgId = msgget(IKey1,0)) == -1)
    {
        perror("msgget");
        exit(2);
    }
   
    printf("KeyID=%x\n",IKey1);
    printf("MsgID=%d\n",nMsgId);
    
    memset(&msg,0x00,sizeof(MSG));
    if((n = msgrcv(nMsgId,(const void*)&msg,sizeof(msg.szText),2L,0))<0)
    {
        perror("msgrcv");
    }
    else
    {
        printf("msgrcv return length=[%d] text=[%s]\n",n,msg.szText);
    }
   
    return 0;
}

运行结果， 消息数变为1， 长度变为6

[root@elm64 ~]# ipcs -q

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    
0x010088c2 0          root       666        12           2           

[root@elm64 ~]# ipcs -q

------ Message Queues --------
key        msqid      owner      perms      used-bytes   messages    
0x010088c2 0          root       666        6            1           

[root@elm64 ~]#