PROLOG | NAME | SYNOPSIS | DESCRIPTION | APPLICATION USAGE | RATIONALE | FUTURE DIRECTIONS | SEE ALSO | COPYRIGHT

sys_shm.h(0P)             POSIX Programmer's Manual            sys_shm.h(0P)

PROLOG         top

       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 behavior), or
       the interface may not be implemented on Linux.

NAME         top

       sys/shm.h — XSI shared memory facility

SYNOPSIS         top

       #include <sys/shm.h>

DESCRIPTION         top

       The <sys/shm.h> header shall define the following symbolic constants:

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

       SHM_RND     Round attach address to SHMLBA.

       SHMLBA      Segment low boundary address multiple.

       The <sys/shm.h> header shall define the following data types through
       typedef:

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

       The <sys/shm.h> header shall define the shmid_ds structure, which
       shall include the following members:

           struct ipc_perm shm_perm   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 shmat().
           time_t          shm_dtime  Time of last shmdt().
           time_t          shm_ctime  Time of last change by shmctl().

       The <sys/shm.h> header shall define the pid_t, size_t, and time_t
       types as described in <sys/types.h>.

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

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

       In addition, the <sys/shm.h> header shall include the <sys/ipc.h>
       header.

       The following sections are informative.

APPLICATION USAGE         top

       None.

RATIONALE         top

       None.

FUTURE DIRECTIONS         top

       None.

SEE ALSO         top

       sys_ipc.h(0p), sys_types.h(0p)

       The System Interfaces volume of POSIX.1‐2008, shmat(3p), shmctl(3p),
       shmdt(3p), shmget(3p)

COPYRIGHT         top

       Portions of this text are reprinted and reproduced in electronic form
       from IEEE Std 1003.1, 2013 Edition, Standard for Information
       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 Corrigendum 1
       applied.) 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.unix.org/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                 2013                       sys_shm.h(0P)