sys_msg.h(3)               POSIX Programmer's Manual              sys_msg.h(3)



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

NNAAMMEE
       sys/msg.h -- XSI message queue structures

SSYYNNOOPPSSIISS
       #include <sys/msg.h>

DDEESSCCRRIIPPTTIIOONN
       The _<_s_y_s_/_m_s_g_._h_> header shall define the following data types through
       ttyyppeeddeeff:

       mmssggqqnnuumm__tt     Used for the number of messages in the message queue.

       mmssgglleenn__tt      Used for the number of bytes allowed in a message queue.

       These types shall be unsigned integer types that are able to store
       values at least as large as a type uunnssiiggnneedd sshhoorrtt.

       The _<_s_y_s_/_m_s_g_._h_> header shall define the following symbolic constant as
       a message operation flag:

       MSG_NOERROR   No error if big message.

       The _<_s_y_s_/_m_s_g_._h_> header shall define the mmssqqiidd__ddss structure, which shall
       include the following members:


           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 _m_s_g_s_n_d().
           pid_t           msg_lrpid  Process ID of last _m_s_g_r_c_v().
           time_t          msg_stime  Time of last _m_s_g_s_n_d().
           time_t          msg_rtime  Time of last _m_s_g_r_c_v().
           time_t          msg_ctime  Time of last change.

       The _<_s_y_s_/_m_s_g_._h_> header shall define the ppiidd__tt, ssiizzee__tt, ssssiizzee__tt, and
       ttiimmee__tt types as described in _<_s_y_s_/_t_y_p_e_s_._h_>.

       The following shall be declared as functions and may also be defined as
       macros. Function prototypes shall be provided.


           int       msgctl(int, int, struct msqid_ds *);
           int       msgget(key_t, int);
           ssize_t   msgrcv(int, void *, size_t, long, int);
           int       msgsnd(int, const void *, size_t, int);

       In addition, the _<_s_y_s_/_m_s_g_._h_> header shall include the _<_s_y_s_/_i_p_c_._h_>
       header.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       None.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       None.

SSEEEE AALLSSOO
       <<ssyyss__iippcc..hh>>, <<ssyyss__ttyyppeess..hh>>

       The System Interfaces volume of POSIX.1-2017, _m_s_g_c_t_l(), _m_s_g_g_e_t(),
       _m_s_g_r_c_v(), _m_s_g_s_n_d()

CCOOPPYYRRIIGGHHTT
       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1-2017, Standard for Information Technology --
       Portable Operating System Interface (POSIX), The Open Group Base
       Specifications Issue 7, 2018 Edition, Copyright (C) 2018 by the
       Institute of Electrical and Electronics Engineers, Inc and The Open
       Group.  In the event of any discrepancy between this version and the
       original IEEE and The Open Group Standard, the original IEEE and The
       Open Group Standard is the referee document. The original Standard can
       be obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page are
       most likely to have been introduced during the conversion of the source
       files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                         sys_msg.h(3)
