1sys_msg.h(0P)              POSIX Programmer's Manual             sys_msg.h(0P)
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PROLOG

6       This  manual  page is part of the POSIX Programmer's Manual.  The Linux
7       implementation of this interface may differ (consult the  corresponding
8       Linux  manual page for details of Linux behavior), or the interface may
9       not be implemented on Linux.
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NAME

13       sys/msg.h — XSI message queue structures
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SYNOPSIS

16       #include <sys/msg.h>
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DESCRIPTION

19       The <sys/msg.h> header shall define the following  data  types  through
20       typedef:
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22       msgqnum_t     Used for the number of messages in the message queue.
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24       msglen_t      Used for the number of bytes allowed in a message queue.
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26       These types shall be unsigned integer types that are able to store val‐
27       ues at least as large as a type unsigned short.
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29       The <sys/msg.h> header shall define the following symbolic constant  as
30       a message operation flag:
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32       MSG_NOERROR   No error if big message.
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34       The <sys/msg.h> header shall define the msqid_ds structure, which shall
35       include the following members:
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37           struct ipc_perm msg_perm   Operation permission structure.
38           msgqnum_t       msg_qnum   Number of messages currently on queue.
39           msglen_t        msg_qbytes Maximum number of bytes allowed on queue.
40           pid_t           msg_lspid  Process ID of last msgsnd().
41           pid_t           msg_lrpid  Process ID of last msgrcv().
42           time_t          msg_stime  Time of last msgsnd().
43           time_t          msg_rtime  Time of last msgrcv().
44           time_t          msg_ctime  Time of last change.
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46       The <sys/msg.h> header shall define the  pid_t,  size_t,  ssize_t,  and
47       time_t types as described in <sys/types.h>.
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49       The following shall be declared as functions and may also be defined as
50       macros. Function prototypes shall be provided.
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52           int       msgctl(int, int, struct msqid_ds *);
53           int       msgget(key_t, int);
54           ssize_t   msgrcv(int, void *, size_t, long, int);
55           int       msgsnd(int, const void *, size_t, int);
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57       In addition, the  <sys/msg.h>  header  shall  include  the  <sys/ipc.h>
58       header.
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60       The following sections are informative.
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APPLICATION USAGE

63       None.
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RATIONALE

66       None.
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FUTURE DIRECTIONS

69       None.
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SEE ALSO

72       <sys_ipc.h>, <sys_types.h>
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74       The  System  Interfaces  volume  of  POSIX.1‐2008,  msgctl(), msgget(),
75       msgrcv(), msgsnd()
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78       Portions of this text are reprinted and reproduced in  electronic  form
79       from IEEE Std 1003.1, 2013 Edition, Standard for Information Technology
80       -- Portable Operating System Interface (POSIX),  The  Open  Group  Base
81       Specifications Issue 7, Copyright (C) 2013 by the Institute of Electri‐
82       cal and Electronics Engineers,  Inc  and  The  Open  Group.   (This  is
83       POSIX.1-2008  with  the  2013  Technical Corrigendum 1 applied.) In the
84       event of any discrepancy between this version and the original IEEE and
85       The  Open Group Standard, the original IEEE and The Open Group Standard
86       is the referee document. The original Standard can be  obtained  online
87       at http://www.unix.org/online.html .
88
89       Any  typographical  or  formatting  errors that appear in this page are
90       most likely to have been introduced during the conversion of the source
91       files  to  man page format. To report such errors, see https://www.ker‐
92       nel.org/doc/man-pages/reporting_bugs.html .
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96IEEE/The Open Group                  2013                        sys_msg.h(0P)
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