## 編譯時 gcc xx.c -o xx -pthread
#include <stdio.h>
#include <sys/types.h>
#include <sys/ipc.h>
#include <stdlib.h>
#include <sys/msg.h>
#include <string.h>
#include <pthread.h>

struct msgbuf {
    long mtype;       /* message type, must be > 0 */     //8
    char
 
 mtext[100];  /* message data */ //可以 為所欲為  100
};

int msqid;

void *readMsg(void *arg)
{
    struct msgbuf sm;
    int ret;
    while(1){
        bzero(sm.mtext,sizeof(sm.mtext));
        ret= msgrcv(msqid,&sm,sizeof(struct msgbuf)-sizeof(long),1,0);
        if(ret<0){
            perror("msgrcv error
 
");
            exit(-1);
        }
        printf("yy:%s\n",sm.mtext);
    }
    return NULL;
}
int main(void)
{
    key_t key = ftok("../xx.c",5);
    if(key<0){
        perror("ftok error");
        exit(-1);
    }
    printf("key:%#x\n",key);

    // 建立或者獲取訊息佇列
    msqid = msgget(key,IPC_CREAT|0666
 
);
    if(msqid<0){
        perror("msgget error");
        exit(-1);
    }
    printf("msqid:%d\n",msqid);
    
    /* 執行緒 */
    pthread_t thread;
    if(pthread_create(&thread,NULL,readMsg,NULL)){
        perror("pthread_create error");
        exit(-1);        
    }

    if(pthread_detach(thread)){
        perror("pthread_detach error");
        exit(-1);
    }
    /* 寫入資料 */
    struct msgbuf sm;
    sm.mtype =2;
    int ret;
    while(1){
        bzero(sm.mtext,sizeof(sm.mtext));
        scanf("%s",sm.mtext);
        ret = msgsnd(msqid,&sm,sizeof(struct msgbuf)-sizeof(long),0);
        if(ret<0){
            perror("msgsnd error");
            exit(-1);
        }
    }
    return 0;
}

## 編譯時 gcc xx.c -o xx -pthread

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

struct msgbuf {
    long mtype;       /* message type, must be > 0 */     //8
    char mtext[100];  /* message data */ //可以 為所欲為  100
};
int msqid;
void *readMsg(void *arg)
{
    struct msgbuf sm;
    int ret;
    while(1){
        bzero(sm.mtext,sizeof(sm.mtext));
        ret= msgrcv(msqid,&sm,sizeof(struct msgbuf)-sizeof(long),2,0);
        if(ret<0){
            perror("msgrcv error");
            exit(-1);
        }
        printf("ls:%s\n",sm.mtext);
    }
    return NULL;
}
int main(void)
{
    key_t key = ftok("../xx.c",5);
    if(key<0){
        perror("ftok error");
        exit(-1);
    }
    printf("key:%#x\n",key);
    // 建立或者獲取訊息佇列
    msqid = msgget(key,IPC_CREAT|0666);
    if(msqid<0){
        perror("msgget error");
        exit(-1);
    }
    printf("msqid:%d\n",msqid);
    /* 執行緒 */
    pthread_t thread;
    if(pthread_create(&thread,NULL,readMsg,NULL)){
        perror("pthread_create error");
        exit(-1);        
    }
    if(pthread_detach(thread)){
        perror("pthread_detach error");
        exit(-1);
    }
    /* 寫入資料 */
    struct msgbuf sm;
    sm.mtype =1;
    int ret;
    while(1){
        bzero(sm.mtext,sizeof(sm.mtext));
        scanf("%s",sm.mtext);
        ret = msgsnd(msqid,&sm,sizeof(struct msgbuf)-sizeof(long),0);
        if(ret<0){
            perror("msgsnd error");
            exit(-1);
        }
    }
    return 0;
}