shm_unlink(3p) — Linux manual page


SHM_UNLINK(3P)            POSIX Programmer's Manual           SHM_UNLINK(3P)

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

       shm_unlink — remove a shared memory object (REALTIME)

SYNOPSIS         top

       #include <sys/mman.h>

       int shm_unlink(const char *name);

DESCRIPTION         top

       The shm_unlink() function shall remove the name of the shared memory
       object named by the string pointed to by name.

       If one or more references to the shared memory object exist when the
       object is unlinked, the name shall be removed before shm_unlink()
       returns, but the removal of the memory object contents shall be
       postponed until all open and map references to the shared memory
       object have been removed.

       Even if the object continues to exist after the last shm_unlink(),
       reuse of the name shall subsequently cause shm_open() to behave as if
       no shared memory object of this name exists (that is, shm_open() will
       fail if O_CREAT is not set, or will create a new shared memory object
       if O_CREAT is set).

RETURN VALUE         top

       Upon successful completion, a value of zero shall be returned.
       Otherwise, a value of −1 shall be returned and errno set to indicate
       the error. If −1 is returned, the named shared memory object shall
       not be changed by this function call.

ERRORS         top

       The shm_unlink() function shall fail if:

       EACCES Permission is denied to unlink the named shared memory object.

       ENOENT The named shared memory object does not exist.

       The shm_unlink() function may fail if:

              The length of the name argument exceeds {_POSIX_PATH_MAX} on
              systems that do not support the XSI option or exceeds
              {_XOPEN_PATH_MAX} on XSI systems, or has a pathname component
              that is longer than {_POSIX_NAME_MAX} on systems that do not
              support the XSI option or longer than {_XOPEN_NAME_MAX} on XSI
              systems.  A call to shm_unlink() with a name argument that
              contains the same shared memory object name as was previously
              used in a successful shm_open() call shall not give an
              [ENAMETOOLONG] error.

       The following sections are informative.

EXAMPLES         top



       Names of memory objects that were allocated with open() are deleted
       with unlink() in the usual fashion. Names of memory objects that were
       allocated with shm_open() are deleted with shm_unlink().  Note that
       the actual memory object is not destroyed until the last close and
       unmap on it have occurred if it was already in use.

RATIONALE         top



       A future version might require the shm_open() and shm_unlink()
       functions to have semantics similar to normal file system operations.

SEE ALSO         top

       close(3p), mmap(3p), munmap(3p), shmat(3p), shmctl(3p), shmdt(3p),

       The Base Definitions volume of POSIX.1‐2008, sys_mman.h(0p)

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 .

       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 .

IEEE/The Open Group                 2013                      SHM_UNLINK(3P)

Pages that refer to this page: sys_mman.h(0p)shmat(3p)shmctl(3p)shmdt(3p)shmget(3p)shm_open(3p)