bsd/man/man2/shm_unlink.2

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  23 .Dd August 31, 2006
  24 .Dt SHM_UNLINK 2
  25 .Os Darwin
  26 .Sh NAME
  27 .Nm shm_unlink
  28 .Nd remove shared memory object
  29 .Sh SYNOPSIS
  30 .Fd #include <sys/mman.h>
  31 .Ft int
  32 .Fn shm_unlink "const char *name"
  33 .Sh DESCRIPTION
  34 The
  35 .Fn shm_unlink
  36 function disassociates the shared memory object specified by
  37 .Fa name
  38 from that name.
  39 The resources associated with the shared memory object remain intact
  40 until the last file descriptor reference is removed, e.g., by
  41 .Xr close 2
  42 or
  43 .Xr munmap 2 ,
  44 at which point the resources are reclaimed
  45 (if no references exist at the time of the call to
  46 .Fn shm_unlink ,
  47 the resources are reclaimed immediately).
  48 The name can only be reused
  49 when it is bound to a new shared memory object with a call to
  50 .Xr shm_open 2
  51 with the
  52 .Dv O_CREAT
  53 flag.
  54 .Sh RETURN VALUES
  55 Upon successful completion, a value of 0 is returned.
  56 Otherwise, a value of -1 is returned and
  57 .Va errno
  58 is set to indicate the error,
  59 and the named shared memory object will remain unchanged.
  60 .Sh ERRORS
  61 The
  62 .Fn shm_unlink
  63 succeeds unless:
  64 .Bl -tag -width Er
  65 .It Bq Er EACCES
  66 Permission is denied to be remove the object.
  67 .It Bq Er ENAMETOOLONG
  68 .Fa name
  69 exceeded the name size limit.
  70 This is currently
  71 .Dv PSHMNAMLEN
  72 characters (defined in
  73 .In sys/posix_shm.h ) ,
  74 but this may change in the future.
  75 .It Bq Er ENOENT
  76 The named object does not exist.
  77 .El
  78 .Sh SEE ALSO
  79 .Xr close 2 ,
  80 .Xr mmap 2 ,
  81 .Xr munmap 2 ,
  82 .Xr shm_open 2 ,
  83 .Xr shmat 2 ,
  84 .Xr shmctl 2
  85 .Sh HISTORY
  86 .Fn shm_open
  87 is specified in the POSIX Realtime Extension (1003.1b-1993/1003.1i-1995).