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-.\" Copyright 1993 Giorgio Ciucci <giorgio@crcc.it>
-.\"
-.\" SPDX-License-Identifier: Linux-man-pages-copyleft
-.\"
-.\" Added correction due to Nick Duffek <nsd@bbc.com>, aeb, 960426
-.\" Modified Wed Nov 6 04:00:31 1996 by Eric S. Raymond <esr@thyrsus.com>
-.\" Modified, 8 Jan 2003, Michael Kerrisk, <mtk.manpages@gmail.com>
-.\" Removed EIDRM from errors - that can't happen...
-.\" Modified, 27 May 2004, Michael Kerrisk <mtk.manpages@gmail.com>
-.\" Added notes on capability requirements
-.\" Modified, 11 Nov 2004, Michael Kerrisk <mtk.manpages@gmail.com>
-.\" Language and formatting clean-ups
-.\" Added notes on /proc files
-.\"
-.TH msgget 2 2023-10-31 "Linux man-pages 6.7"
-.SH NAME
-msgget \- get a System V message queue identifier
-.SH LIBRARY
-Standard C library
-.RI ( libc ", " \-lc )
-.SH SYNOPSIS
-.nf
-.B #include <sys/msg.h>
-.P
-.BI "int msgget(key_t " key ", int " msgflg );
-.fi
-.SH DESCRIPTION
-The
-.BR msgget ()
-system call returns the System\ V message queue identifier associated
-with the value of the
-.I key
-argument.
-It may be used either to obtain the identifier of a previously created
-message queue (when
-.I msgflg
-is zero and
-.I key
-does not have the value
-.BR IPC_PRIVATE ),
-or to create a new set.
-.P
-A new message queue is created if
-.I key
-has the value
-.B IPC_PRIVATE
-or
-.I key
-isn't
-.BR IPC_PRIVATE ,
-no message queue with the given key
-.I key
-exists, and
-.B IPC_CREAT
-is specified in
-.IR msgflg .
-.P
-If
-.I msgflg
-specifies both
-.B IPC_CREAT
-and
-.B IPC_EXCL
-and a message queue already exists for
-.IR key ,
-then
-.BR msgget ()
-fails with
-.I errno
-set to
-.BR EEXIST .
-(This is analogous to the effect of the combination
-.B O_CREAT | O_EXCL
-for
-.BR open (2).)
-.P
-Upon creation, the least significant bits of the argument
-.I msgflg
-define the permissions of the message queue.
-These permission bits have the same format and semantics
-as the permissions specified for the
-.I mode
-argument of
-.BR open (2).
-(The execute permissions are not used.)
-.P
-If a new message queue is created,
-then its associated data structure
-.I msqid_ds
-(see
-.BR msgctl (2))
-is initialized as follows:
-.IP \[bu] 3
-.I msg_perm.cuid
-and
-.I msg_perm.uid
-are set to the effective user ID of the calling process.
-.IP \[bu]
-.I msg_perm.cgid
-and
-.I msg_perm.gid
-are set to the effective group ID of the calling process.
-.IP \[bu]
-The least significant 9 bits of
-.I msg_perm.mode
-are set to the least significant 9 bits of
-.IR msgflg .
-.IP \[bu]
-.IR msg_qnum ,
-.IR msg_lspid ,
-.IR msg_lrpid ,
-.IR msg_stime ,
-and
-.I msg_rtime
-are set to 0.
-.IP \[bu]
-.I msg_ctime
-is set to the current time.
-.IP \[bu]
-.I msg_qbytes
-is set to the system limit
-.BR MSGMNB .
-.P
-If the message queue already exists the permissions are
-verified, and a check is made to see if it is marked for
-destruction.
-.SH RETURN VALUE
-On success,
-.BR msgget ()
-returns the message queue identifier (a nonnegative integer).
-On failure, \-1 is returned, and
-.I errno
-is set to indicate the error.
-.SH ERRORS
-.TP
-.B EACCES
-A message queue exists for
-.IR key ,
-but the calling process does not have permission to access the queue,
-and does not have the
-.B CAP_IPC_OWNER
-capability in the user namespace that governs its IPC namespace.
-.TP
-.B EEXIST
-.B IPC_CREAT
-and
-.B IPC_EXCL
-were specified in
-.IR msgflg ,
-but a message queue already exists for
-.IR key .
-.TP
-.B ENOENT
-No message queue exists for
-.I key
-and
-.I msgflg
-did not specify
-.BR IPC_CREAT .
-.TP
-.B ENOMEM
-A message queue has to be created but the system does not have enough
-memory for the new data structure.
-.TP
-.B ENOSPC
-A message queue has to be created but the system limit for the maximum
-number of message queues
-.RB ( MSGMNI )
-would be exceeded.
-.SH STANDARDS
-POSIX.1-2008.
-.SH HISTORY
-POSIX.1-2001, SVr4.
-.SS Linux
-Until Linux 2.3.20, Linux would return
-.B EIDRM
-for a
-.BR msgget ()
-on a message queue scheduled for deletion.
-.SH NOTES
-.B IPC_PRIVATE
-isn't a flag field but a
-.I key_t
-type.
-If this special value is used for
-.IR key ,
-the system call ignores everything but the least significant 9 bits of
-.I msgflg
-and creates a new message queue (on success).
-.P
-The following is a system limit on message queue resources affecting a
-.BR msgget ()
-call:
-.TP
-.B MSGMNI
-System-wide limit on the number of message queues.
-Before Linux 3.19,
-.\" commit 0050ee059f7fc86b1df2527aaa14ed5dc72f9973
-the default value for this limit was calculated using a formula
-based on available system memory.
-Since Linux 3.19, the default value is 32,000.
-On Linux, this limit can be read and modified via
-.IR /proc/sys/kernel/msgmni .
-.SH BUGS
-The name choice
-.B IPC_PRIVATE
-was perhaps unfortunate,
-.B IPC_NEW
-would more clearly show its function.
-.SH SEE ALSO
-.BR msgctl (2),
-.BR msgrcv (2),
-.BR msgsnd (2),
-.BR ftok (3),
-.BR capabilities (7),
-.BR mq_overview (7),
-.BR sysvipc (7)