msg

#include <sys/types.h> #include <sys/msg.h> #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <sys/ipc.h> #include <string.h> #include <signal.h> struct msg_buf     {         int mtype;         char data[255];     }; int main() {         key_t key;         pid_t pid;         int msgid;         int ret;         struct msg_buf msgbuf;         struct msg_buf msgbuf1;         struct msg_buf msgbuf2;         struct msg_buf msgbuf3;         int i = 0;         key=ftok(".",'a');         printf("key =[%x]\n",key);         msgid=msgget(key,IPC_CREAT|0666); /*通过文件对应*/         if(msgid==-1)         {                 printf("create error\n");                 return -1;         }          if((pid = fork()) < 0)          {              perror("fork error");              exit(0);          }          if( pid > 0)        {             msgbuf1.mtype = 1;             strcpy(msgbuf1.data,"test haha1");             msgbuf2.mtype = 2;             strcpy(msgbuf2.data,"test haha2");             msgbuf3.mtype = 3;             strcpy(msgbuf3.data,"test haha3");             ret=msgsnd(msgid,&msgbuf1,sizeof(msgbuf1.data),IPC_NOWAIT);             if(ret==-1)             {                 printf("send message err\n");                 return -1;             }             //sleep(3);             ret=msgsnd(msgid,&msgbuf2,sizeof(msgbuf2.data),IPC_NOWAIT);             if(ret==-1)             {                 printf("send message err\n");                 return -1;             }            // sleep(3);             ret=msgsnd(msgid,&msgbuf3,sizeof(msgbuf3.data),IPC_NOWAIT);             if(ret==-1)             {                 printf("send message err\n");                 return -1;             }            // sleep(3);            // kill(pid,SIGSTOP);             waitpid(pid,NULL,0);             exit(0);        }          if( pid == 0)          {             while(i < 3)             {                 i++;                 memset(&msgbuf,0,sizeof(msgbuf));                 ret=msgrcv(msgid,&msgbuf,sizeof(msgbuf.data),i,0);                 if(ret==-1)                 {                     printf("recv message err\n");                     return -1;                 }                 printf("recv msg =[%s]\n",msgbuf.data);                 sleep(1);             }                exit(0);          }      return 0;