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MSGGET(2) System Calls Manual MSGGET(2)


msggetget message queue


#include <sys/msg.h>
msgget(key_t key, int msgflg);


msgget() returns the message queue identifier associated with key. A message queue identifier is a unique integer greater than zero.
A message queue is created if either key is equal to IPC_PRIVATE, or key does not have a message queue identifier associated with it, and the IPC_CREAT bit is set in msgflg.
If a new message queue is created, the data structure associated with it (the msqid_ds structure, see msgctl(2)) is initialized as follows:


Upon successful completion a positive message queue identifier is returned. Otherwise, -1 is returned and the global variable errno is set to indicate the error.


A message queue is already associated with key and the caller has no permission to access it.
Both IPC_CREAT and IPC_EXCL are set in msgflg, and a message queue is already associated with key.
A new message queue could not be created because the system limit for the number of message queues has been reached.
IPC_CREAT was not set in msgflg and no message queue associated with key was found.


msgctl(2), msgrcv(2), msgsnd(2), ftok(3)


Message queues appeared in AT&T System V Release 1 UNIX.
November 15, 2014 OpenBSD-current