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Manual Pages  — MSGGET

NAME

msgget – get message queue

CONTENTS

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <sys/msg.h>

int
msgget(key_t key, int msgflg);

DESCRIPTION

The msgget() function 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:

RETURN VALUES

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.

ERRORS

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

SEE ALSO

msgctl(2), msgrcv(2), msgsnd(2)

HISTORY

Message queues appeared in the first release of AT&T V .

MSGGET (2) March 4, 2018

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