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



PPRROOLLOOGG
       This manual page is part of the POSIX Programmer's Manual.  The OS
       implementation of this interface may differ (consult the corresponding
       OS manual page for details of OS behavior), or the interface may not be
       implemented on OS.

NNAAMMEE
       shm_unlink -- remove a shared memory object (RREEAALLTTIIMMEE)

SSYYNNOOPPSSIISS
       #include <sys/mman.h>

       int shm_unlink(const char *_n_a_m_e);

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

       If one or more references to the shared memory object exist when the
       object is unlinked, the name shall be removed before _s_h_m___u_n_l_i_n_k()
       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 _s_h_m___u_n_l_i_n_k(),
       reuse of the name shall subsequently cause _s_h_m___o_p_e_n() to behave as if
       no shared memory object of this name exists (that is, _s_h_m___o_p_e_n() will
       fail if O_CREAT is not set, or will create a new shared memory object
       if O_CREAT is set).

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

EERRRROORRSS
       The _s_h_m___u_n_l_i_n_k() function shall fail if:

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

       EENNOOEENNTT The named shared memory object does not exist.

       The _s_h_m___u_n_l_i_n_k() function may fail if:

       EENNAAMMEETTOOOOLLOONNGG
              The length of the _n_a_m_e 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 _s_h_m___u_n_l_i_n_k() with a _n_a_m_e argument that
              contains the same shared memory object name as was previously
              used in a successful _s_h_m___o_p_e_n() call shall not give an
              [[EENNAAMMEETTOOOOLLOONNGG]] error.

       _T_h_e _f_o_l_l_o_w_i_n_g _s_e_c_t_i_o_n_s _a_r_e _i_n_f_o_r_m_a_t_i_v_e_.

EEXXAAMMPPLLEESS
       None.

AAPPPPLLIICCAATTIIOONN UUSSAAGGEE
       Names of memory objects that were allocated with _o_p_e_n() are deleted
       with _u_n_l_i_n_k() in the usual fashion. Names of memory objects that were
       allocated with _s_h_m___o_p_e_n() are deleted with _s_h_m___u_n_l_i_n_k().  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.

RRAATTIIOONNAALLEE
       None.

FFUUTTUURREE DDIIRREECCTTIIOONNSS
       A future version might require the _s_h_m___o_p_e_n() and _s_h_m___u_n_l_i_n_k()
       functions to have semantics similar to normal file system operations.

SSEEEE AALLSSOO
       _c_l_o_s_e(), _m_m_a_p(), _m_u_n_m_a_p(), _s_h_m_a_t(), _s_h_m_c_t_l(), _s_h_m_d_t(), _s_h_m___o_p_e_n()

       The Base Definitions volume of POSIX.1-2017, <<ssyyss__mmmmaann..hh>>

CCOOPPYYRRIIGGHHTT
       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 at http://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, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .



IEEE/The Open Group                  2017                        SHM_UNLINK(3)
