MSGGET(2) BSD Programmer's Manual MSGGET(2)NAMEmsgget - get message queue
SYNOPSIS
#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/msg.h>
int
msgget(key_t key, int msgflg);
DESCRIPTIONmsgget() returns the message queue identifier associated with key. A mes-
sage 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 initial-
ized 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 re-
turned. Otherwise, -1 is returned and the global variable errno is set
to indicate the error.
ERRORS
[EACESS] 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 mes-
sage 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 asso-
ciated with key was found.
SEE ALSOmsgctl(2), msgrcv(2), msgsnd(2)4th Berkeley Distribution July 3, 1996 1