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<pre> <span class="headline">sys_shm.h(0P)             POSIX Pro‐
grammer’s  Manual             sys_shm.h(0P)</span>  </pre> <h2><a
id="PROLOG" href="#PROLOG"></a>PROLOG  &nbsp; &nbsp; &nbsp;  &nb‐
sp;        <a        href="#top_of_page"><span        class="top‐
link">top</span></a></h2><pre>
       This manual page is part of the POSIX Programmer’s Manual.
The Linux
       implementation of this interface may differ (consult the
       corresponding  Linux  manual page for details of Linux be‐
havior), or
       the interface may not be  implemented  on  Linux.   </pre>
<h2><a id="NAME" href="#NAME"></a>NAME  &nbsp; &nbsp; &nbsp; &nb‐
sp;        <a        href="#top_of_page"><span        class="top‐
link">top</span></a></h2><pre>
       sys/shm.h  —  XSI  shared  memory  facility  </pre> <h2><a
id="SYNOPSIS" href="#SYNOPSIS"></a>SYNOPSIS  &nbsp; &nbsp; &nbsp;
&nbsp;       <a       href="#top_of_page"><span       class="top‐
link">top</span></a></h2><pre>
       #include &lt;sys/shm.h&gt; </pre> <h2><a  id="DESCRIPTION"
href="#DESCRIPTION"></a>DESCRIPTION   &nbsp; &nbsp; &nbsp; &nbsp;
<a             href="#top_of_page"><span              class="top‐
link">top</span></a></h2><pre>
       The  <i>&lt;sys/shm.h&gt;</i> header shall define the fol‐
lowing symbolic constants:

       SHM_RDONLY  Attach read‐only (else read‐write).

       SHM_RND     Round attach address to SHMLBA.

       SHMLBA      Segment low boundary address multiple.

       The <i>&lt;sys/shm.h&gt;</i> header shall define the  fol‐
lowing data types through
       <b>typedef</b>:

       <b>shmatt_t    </b>Unsigned integer used for the number of
current attaches
                   that must be able to store values at least  as
large as a
                   type <b>unsigned short</b>.

       The   <i>&lt;sys/shm.h&gt;</i>  header  shall  define  the
<b>shmid_ds </b>structure, which
       shall include the following members:

           <b>struct ipc_perm shm_perm   </b>Operation permission
structure.
           size_t          shm_segsz  Size of segment in bytes.
           pid_t            shm_lpid    Process ID of last shared
memory operation.
           pid_t           shm_cpid   Process ID of creator.
           shmatt_t        shm_nattch Number of current attaches.
           time_t             shm_atime      Time     of     last
<i>shmat</i>().
           time_t              shm_dtime      Time     of    last
<i>shmdt</i>().
           time_t          shm_ctime   Time  of  last  change  by
<i>shmctl</i>().

       The   <i>&lt;sys/shm.h&gt;</i>  header  shall  define  the
<b>pid_t</b>, <b>size_t</b>, and <b>time_t</b>
       types as described in <i>&lt;sys/types.h&gt;</i>.

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

           <b>void *shmat(int, const void *, int);</b>
           <b>int   shmctl(int, int, struct shmid_ds *);</b>
           <b>int   shmdt(const void *);</b>
           <b>int   shmget(key_t, size_t, int);</b>

       In addition, the <i>&lt;sys/shm.h&gt;</i> header shall in‐
clude the <i>&lt;sys/ipc.h&gt;</i>
       header.

       <i>The  following  sections  are  informative.</i>  </pre>
<h2><a  id="APPLICATION_USAGE"  href="#APPLICATION_USAGE"></a>AP‐
PLICATION    USAGE     &nbsp;    &nbsp;    &nbsp;    &nbsp;    <a
href="#top_of_page"><span                             class="top‐
link">top</span></a></h2><pre>
       None.    </pre>   <h2><a   id="RATIONALE"    href="#RATIO‐
NALE"></a>RATIONALE     &nbsp;    &nbsp;    &nbsp;    &nbsp;   <a
href="#top_of_page"><span                             class="top‐
link">top</span></a></h2><pre>
       None.   </pre>  <h2><a  id="FUTURE_DIRECTIONS"  href="#FU‐
TURE_DIRECTIONS"></a>FUTURE DIRECTIONS  &nbsp; &nbsp; &nbsp; &nb‐
sp;        <a        href="#top_of_page"><span        class="top‐
link">top</span></a></h2><pre>
       None.    </pre>   <h2><a   id="SEE_ALSO"    href="#SEE_AL‐
SO"></a>SEE    ALSO     &nbsp;    &nbsp;    &nbsp;    &nbsp;   <a
href="#top_of_page"><span                             class="top‐
link">top</span></a></h2><pre>
       <a  href="../man0/sys_ipc.h.0p.html">sys_ipc.h(0p)</a>, <a
href="../man0/sys_types.h.0p.html">sys_types.h(0p)</a>

       The  System  Interfaces   volume   of   POSIX.1‐2008,   <a
href="../man3/shmat.3p.html">shmat(3p)</a>, <a href="../man3/shm‐
ctl.3p.html">shmctl(3p)</a>,
       <a     href="../man3/shmdt.3p.html">shmdt(3p)</a>,      <a
href="../man3/shmget.3p.html">shmget(3p)</a>     </pre>    <h2><a
id="COPYRIGHT"  href="#COPYRIGHT"></a>COPYRIGHT   &nbsp;   &nbsp;
&nbsp;    &nbsp;    <a    href="#top_of_page"><span   class="top‐
link">top</span></a></h2><pre>
       Portions of this text  are  reprinted  and  reproduced  in
electronic form
       from  IEEE Std 1003.1, 2013 Edition, Standard for Informa‐
tion
       Technology ‐‐ Portable Operating System Interface (POSIX),
The Open
       Group  Base  Specifications Issue 7, Copyright (C) 2013 by
the
       Institute of Electrical and Electronics Engineers, Inc and
The Open
       Group.  (This is POSIX.1‐2008 with the 2013 Technical Cor‐
rigendum 1
       applied.) In the event of  any  discrepancy  between  this
version and
       the  original IEEE and The Open Group Standard, the origi‐
nal IEEE and
       The Open Group Standard is the referee document. The orig‐
inal
       Standard     can     be     obtained    online    at    <a
href="http://www.unix.org/online.html">http://www.unix.org/on‐
line.html</a> .

       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
       <a      href="https://www.kernel.org/doc/man‐pages/report‐
ing_bugs.html">https://www.kernel.org/doc/man‐pages/report‐
ing_bugs.html</a> .

<span class="footline">IEEE/The Open  Group                  2013
sys_shm.h(0P)</span> </pre>

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