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MSGGET(2)		  FreeBSD System Calls Manual		     MSGGET(2)

NAME
     msgget -- get message queue

LIBRARY
     Standard C	Library	(libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/ipc.h>
     #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:

     +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_cbytes, 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 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 System V UNIX.

FreeBSD	9.2			 July 9, 2009			   FreeBSD 9.2

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | ERRORS | SEE ALSO | HISTORY

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