msgget(2) System Calls msgget(2)NAMEmsgget - get message queue
SYNOPSIS
#include <sys/msg.h>
int msgget(key_t key, int msgflg);
DESCRIPTION
The msgget() argument returns the message queue identifier associated
with key.
A message queue identifier and associated message queue and data struc‐
ture (see intro(2)) are created for key if one of the following are
true:
· key is IPC_PRIVATE.
· key does not already have a message queue identifier associated
with it, and (msgflg&IPC_CREAT) is true.
On creation, the data structure associated with the new message queue
identifier is initialized as follows:
· msg_perm.cuid, msg_perm.uid, msg_perm.cgid, and msg_perm.gid are
set to the effective user ID and effective group ID, respectively,
of the calling process.
· The low-order 9 bits of msg_perm.mode are set to the low-order 9
bits of msgflg.
· msg_qnum, msg_lspid, msg_lrpid, msg_stime, and msg_rtime are set
to 0.
· msg_ctime is set to the current time.
· msg_qbytes is set to the system limit. See NOTES.
RETURN VALUES
Upon successful completion, a non-negative integer representing a mes‐
sage queue identifier is returned. Otherwise, −1 is returned and errno
is set to indicate the error.
ERRORS
The msgget() function will fail if:
EACCES A message queue identifier exists for key, but opera‐
tion permission (see intro(2)) as specified by the low-
order 9 bits of msgflg would not be granted.
EEXIST A message queue identifier exists for key but
(msgflg&IPC_CREAT) and (msgflg&IPC_EXCL) are both true.
ENOENT A message queue identifier does not exist for key and
(msgflg&IPC_CREAT) is false.
ENOSPC A message queue identifier is to be created but the
system-imposed limit on the maximum number of allowed
message queue identifiers system wide would be
exceeded. See NOTES.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Standard │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOrctladm(1M), intro(2), msgctl(2), msgrcv(2), msgsnd(2), setrctl(2),
ftok(3C), attributes(5), standards(5)NOTES
The system-defined limit used to initialize msg_qbytes is the minimum
enforced value of the calling process's process.max-msg-qbytes resource
control.
The system-imposed limit on the number of message queue identifiers is
maintained on a per-project basis using the project.max-msg-ids
resource control.
See rctladm(1M) and setrctl(2) for information about using resource
controls.
SunOS 5.10 11 Feb 2003 msgget(2)
