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msgget(2) [opensolaris man page]

msgget(2)							   System Calls 							 msgget(2)

NAME
msgget - 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 structure (see Intro(2)) are created for key if one of the following are true: o key is IPC_PRIVATE. o 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: o msg_perm.cuid, msg_perm.uid, msg_perm.cgid, and msg_perm.gid are set to the effective user ID and effective group ID, respec- tively, of the calling process. o The low-order 9 bits of msg_perm.mode are set to the low-order 9 bits of msgflg. o msg_qnum, msg_lspid, msg_lrpid, msg_stime, and msg_rtime are set to 0. o msg_ctime is set to the current time. o msg_qbytes is set to the system limit. See NOTES. RETURN VALUES
Upon successful completion, a non-negative integer representing a message 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 operation 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 identi- fiers 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 ALSO
rctladm(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. The zone.max-msg-ids resource control restricts the total amount of message queue identifiers that can be allocated by a zone. See rctladm(1M) and setrctl(2) for information about using resource controls. SunOS 5.11 14 Aug 2006 msgget(2)

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MSGGET(2)						      BSD System Calls Manual							 MSGGET(2)

NAME
msgget -- get message queue identifier LIBRARY
Standard C Library (libc, -lc) SYNOPSIS
#include <sys/msg.h> int msgget(key_t key, int msgflg); DESCRIPTION
The msgget() system call 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 both the IPC_CREAT bit and the IPC_EXCL bit are set in msgflg, and key has a message queue identifier associated with it already, the operation will fail. If a new message queue is created, the data structure associated with it (the msqid_ds structure, see msgctl(2)) is initialized as follows: o msg_perm.cuid and msg_perm.uid are set to the effective uid of the calling process. o msg_perm.gid and msg_perm.cgid are set to the effective gid of the calling process. o msg_perm.mode is set to the lower 9 bits of msgflg. o msg_qnum, msg_lspid, msg_lrpid, msg_rtime, and msg_stime are set to 0. o msg_qbytes is set to the system wide maximum value for the number of bytes in a queue (MSGMNB). o msg_ctime is set to the current time. 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 is not set in msgflg and no message queue associated with key was found. SEE ALSO
msgctl(2), msgrcv(2), msgsnd(2), ftok(3) STANDARDS
The msgget system call conforms to X/Open System Interfaces and Headers Issue 5 (``XSH5''). HISTORY
Message queues appeared in the first release of AT&T System V UNIX. BSD
May 13, 2004 BSD
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