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shm_unlink(3p) — Linux manual page

SHM_UNLINK(3P)          POSIX Programmer's ManualSHM_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

       Theshm_unlink() function shall remove the name of the shared       memory object named by the string pointed to byname.       If one or more references to the shared memory object exist when       the object is unlinked, the name shall be removed beforeshm_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 lastshm_unlink(),       reuse of the name shall subsequently causeshm_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 anderrno set to       indicate the error. If -1 is returned, the named shared memory       object shall not be changed by this function call.

ERRORS        top

       Theshm_unlink() function shall fail if:EACCESPermission is denied to unlink the named shared memory              object.ENOENTThe named shared memory object does not exist.       Theshm_unlink() function may fail if:ENAMETOOLONG              The length of thename 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 toshm_unlink()              with aname argument that contains the same shared memory              object name as was previously used in a successfulshm_open() call shall not give an[ENAMETOOLONG]error.The following sections are informative.

EXAMPLES        top

       None.

APPLICATION USAGE        top

       Names of memory objects that were allocated withopen() are       deleted withunlink() in the usual fashion. Names of memory       objects that were allocated withshm_open() are deleted withshm_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

       None.

FUTURE DIRECTIONS        top

       A future version might require theshm_open() andshm_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),shm_open(3p)       The Base Definitions volume of POSIX.1‐2017,sys_mman.h(0p)

COPYRIGHT        top

       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 athttp://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, seehttps://www.kernel.org/doc/man-pages/reporting_bugs.html .IEEE/The Open Group                2017SHM_UNLINK(3P)

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

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