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.TH MSG.H 3HEAD "Sep 10, 2004"
.SH NAME
msg.h, msg \- message queue structures
.SH SYNOPSIS
.LP
.nf
#include <\fBsys/msg.h\fR>
.fi

.SH DESCRIPTION
.sp
.LP
The <\fBsys/msg.h\fR> header defines the following data types through
\fBtypedef\fR:
.sp
.ne 2
.na
\fB\fBmsgqnum_t\fR\fR
.ad
.RS 13n
used for the number of messages in the message queue
.RE

.sp
.ne 2
.na
\fB\fBmsglen_t\fR\fR
.ad
.RS 13n
used for the number of bytes allowed in the message queue
.RE

.sp
.LP
These types are unsigned integer types that are able to store values at least
as large as a type unsigned short.
.sp
.LP
The <\fBsys/msg.h\fR> header defines the following constant as a message
operation flag:
.sp
.ne 2
.na
\fB\fBMSG_NOERROR\fR\fR
.ad
.RS 15n
no error if big message
.RE

.sp
.LP
The \fBmsqid_ds\fR structure contains the following members:
.sp
.in +2
.nf
struct ipc_perm    msg_perm      Operation permission structure.
msgqnum_t          msg_qnum      Number of messages currently on
                                 queue.
msglen_t           msg_qbytes    Maximum number of bytes allowed
                                 on queue.
pid_t              msg_lspid     Process ID of last msgsnd(2).
pid_t              msg_lrpid     Process ID of last msgrcv(2).
time_t             msg_stime     Time of last \fBmsgsnd()\fR.
time_t             msg_rtime     Time of last \fBmsgrcv()\fR.
time_t             msg_ctime     Time of last change.
.fi
.in -2

.sp
.LP
The \fBpid_t\fR, \fBtime_t\fR, \fBkey_t\fR, \fBsize_t\fR, and \fBssize_t\fR
types are defined as described in <\fBsys/types.h\fR>. See \fBtypes\fR(3HEAD).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(7) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Standard
.TE

.SH SEE ALSO
.sp
.LP
.BR msgctl (2),
.BR msgget (2),
.BR msgrcv (2),
.BR msgsnd (2),
.BR ipc.h (3HEAD),
.BR types.h (3HEAD),
.BR attributes (7),
.BR standards (7)