# multiple user of msgget(): Permission denied



## ecnux (Jun 1, 2011)

I used ipc message to control the threads and process, and I want to use some threads to read the queue and others to write.

But I have got Permission Denied error when the msgget on the same KEY is invoked a second time.

In details:

```
if(msgget(6789, IPC_CREAT|0777)==-1) perror();
          and i would get "Permission denied".
   if(msgget(6789, IPC_CREAT|IPC_EXCL|0777)==-1) perror();
          and i would get "File exists"
```

I guess that maybe ipc message can not be invoked two times, it's really stange!


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## SirDice (Jun 1, 2011)

The msgget(2) function creates a message queue if it doesn't exist. You're trying to create the same queue twice.


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