msg.c

linux编程的简单例子

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#define BUFSZ 512
struct message{
	long msg_type;
	char msg_text[BUFSZ];
};

int main()
{
	int qid;
	key_t key;
	int len;
	struct message msg;

	if((key=ftok(".",'a'))==-1){
		perror("ftok");
		exit(1);
	}
	if((qid=msgget(key,IPC_CREAT|0666))==-1){
		perror("msgget");
		exit(1);
	}
	printf("opened queue %d\n",qid);
	puts("Please enter the message to queue:");
	if((fgets((&msg)->msg_text,BUFSZ,stdin))==NULL){
		puts("no message");
		exit(1);
	}
	msg.msg_type = getpid();
	len = strlen(msg.msg_text);
	if((msgsnd(qid,&msg,len,0))<0){
		perror("message posted");
		exit(1);
	}
	if(msgrcv(qid,&msg,BUFSZ,0,0)<0){
		perror("msgrcv");
		exit(1);
	}
	printf("message is:%s\n",(&msg)->msg_text);
	if((msgctl(qid,IPC_RMID,NULL))<0){
		perror("msgctl");
		exit(1);
	}
	exit(0);
}