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returns
the message queue identifier associated with A message queue identifier
is a unique integer greater than zero.
A message queue is created if either
is equal to IPC_PRIVATE, or does not have a message queue identifier
associated with it, and the IPC_CREAT bit is set in
If a new message
queue is created, the data structure associated with it (the structure,
see is initialized as follows: and are set to the effective uid of
the calling process. and are set to the effective gid of the calling
process. is set to the lower 9 bits of and are set to 0 is
set to the system wide maximum value for the number of bytes in a queue
(MSGMNB). is set to the current time.
Upon successful completion
a positive message queue identifier is returned. Otherwise, -1 is returned
and the global variable is set to indicate the error.
A message
queue is already associated with and the caller has no permission to access
it. Both IPC_CREAT and IPC_EXCL are set in and a message queue is already
associated with 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 and no message queue associated with was found.
Message queues appeared in the first release of AT&T Unix System
V.
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