1sys_shm.h(0P)              POSIX Programmer's Manual             sys_shm.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/shm.h — XSI shared memory facility
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SYNOPSIS

16       #include <sys/shm.h>
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DESCRIPTION

19       The <sys/shm.h> header shall define the following symbolic constants:
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21       SHM_RDONLY  Attach read-only (else read-write).
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23       SHM_RND     Round attach address to SHMLBA.
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25       SHMLBA      Segment low boundary address multiple.
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27       The <sys/shm.h> header shall define the following  data  types  through
28       typedef:
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30       shmatt_t    Unsigned  integer  used  for the number of current attaches
31                   that must be able to store values at least as  large  as  a
32                   type unsigned short.
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34       The <sys/shm.h> header shall define the shmid_ds structure, which shall
35       include the following members:
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37           struct ipc_perm shm_perm   Operation permission structure.
38           size_t          shm_segsz  Size of segment in bytes.
39           pid_t           shm_lpid   Process ID of last shared memory operation.
40           pid_t           shm_cpid   Process ID of creator.
41           shmatt_t        shm_nattch Number of current attaches.
42           time_t          shm_atime  Time of last shmat().
43           time_t          shm_dtime  Time of last shmdt().
44           time_t          shm_ctime  Time of last change by shmctl().
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46       The <sys/shm.h> header shall define the pid_t, size_t, and time_t types
47       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           void *shmat(int, const void *, int);
53           int   shmctl(int, int, struct shmid_ds *);
54           int   shmdt(const void *);
55           int   shmget(key_t, size_t, int);
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57       In addition, the  <sys/shm.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,  shmat(),  shmctl(),
75       shmdt(), shmget()
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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_shm.h(0P)
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