shmdt报错，请大侠帮忙
GUN/Linux编程指南中的例子，源代码如下：/*
* atshm.c - Attaching a shared memory segment
*/
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <stdio.h>
#include <stdlib.h>
int main(int argc, char *argv[])
{
int shmid; /* Segment ID */
char *shmbuf; /* Address in process */
/* Expect an segment id on the command line */
if (argc != 2) {
puts("USAGE: atshm <identifier>");
exit(EXIT_FAILURE);
}
shmid = atoi(argv);
/* Attach the segment */
if ((shmbuf = shmat(shmid, 0, 0)) < (char *)0) {
perror("shmat");
exit(EXIT_FAILURE);
}
/* Where is it attached? */
printf("segment attached at %p\n", shmbuf);
/* See, we really are attached! */
system("ipcs -m");
/* Detach */
if ((shmdt(shmbuf)) < 0) {
perror("shmdt");
exit(EXIT_FAILURE);
}
puts("segment detached");
/* Yep, we really did detach it */
system("ipcs -m");
exit(EXIT_SUCCESS);
}
编译：gcc atshm.c -o atshm
执行：./atshm 11137就报错了如图：
shmid z这个参数可以随意指定么？shmat 那返回的就是 -1 吧，貌似已经出错了
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