1SHM_UNLINK(P)              POSIX Programmer's Manual             SHM_UNLINK(P)
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NAME

6       shm_unlink - remove a shared memory object (REALTIME)
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SYNOPSIS

9       #include <sys/mman.h>
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11       int shm_unlink(const char *name);
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DESCRIPTION

15       The  shm_unlink()  function  shall remove the name of the shared memory
16       object named by the string pointed to by name.
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18       If one or more references to the shared memory object  exist  when  the
19       object  is  unlinked,  the  name  shall  be removed before shm_unlink()
20       returns, but the removal of the memory object contents shall  be  post‐
21       poned  until  all  open  and map references to the shared memory object
22       have been removed.
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24       Even if the object continues to exist after the last shm_unlink(),  re‐
25       use  of the name shall subsequently cause shm_open() to behave as if no
26       shared memory object of this name exists (that is, shm_open() will fail
27       if  O_CREAT  is  not  set, or will create a new shared memory object if
28       O_CREAT is set).
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RETURN VALUE

31       Upon successful completion, a value of zero shall be  returned.  Other‐
32       wise,  a  value  of  -1 shall be returned and errno set to indicate the
33       error. If -1 is returned, the named shared memory object shall  not  be
34       changed by this function call.
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ERRORS

37       The shm_unlink() function shall fail if:
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39       EACCES Permission is denied to unlink the named shared memory object.
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41       ENAMETOOLONG
42              The length of the name argument exceeds {PATH_MAX} or a pathname
43              component is longer than {NAME_MAX}.
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45       ENOENT The named shared memory object does not exist.
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48       The following sections are informative.
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EXAMPLES

51       None.
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APPLICATION USAGE

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

61       None.
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FUTURE DIRECTIONS

64       None.
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SEE ALSO

67       close() , mmap() , munmap() , shmat() , shmctl() , shmdt() , shm_open()
68       , the Base Definitions volume of IEEE Std 1003.1-2001, <sys/mman.h>
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71       Portions  of  this text are reprinted and reproduced in electronic form
72       from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
73       --  Portable  Operating  System  Interface (POSIX), The Open Group Base
74       Specifications Issue 6, Copyright (C) 2001-2003  by  the  Institute  of
75       Electrical  and  Electronics  Engineers, Inc and The Open Group. In the
76       event of any discrepancy between this version and the original IEEE and
77       The  Open Group Standard, the original IEEE and The Open Group Standard
78       is the referee document. The original Standard can be  obtained  online
79       at http://www.opengroup.org/unix/online.html .
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83IEEE/The Open Group                  2003                        SHM_UNLINK(P)
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