system V ipc结构

struct ipc_perm {
        uid_t uid;      /*owner's user id*/
        gid_t gid;      /*owner's group id*/
        uid_t cuid;     /*creator's user id*/
        gid_t cgid;     /*creator's group id*/
        mode_t mode;    /*read-write permissions*/
        ulong_t seq;    /*slot usage sequence number*/
        key_t key;      /*IPC key*/
};

内核给每个IPC对象维护一个信息结构，其内容跟内核给文件维护的信息类似。

#include <stdio.h>
#include <stdlib.h>
#include <sys/msg.h>
 
int main(int argc, char **argv) {
    int i, msqid;
 
    for(i=0;i<10;i++) {
        if((msqid=msgget(IPC_PRIVATE, 0644|IPC_CREAT))==-1) {
            fprintf(stderr, "msgget error.\n");
            exit(-1);
        }
        printf("msqid=%d\n", msqid);
 
        if(msgctl(msqid, IPC_RMID, NULL)==-1) {
            fprintf(stderr, "msgctl error.\n");
            exit(-1);
        }
    }
 
    exit(0);
}