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.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved
.TH "SHM_UNLINK" P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" shm_unlink
.SH NAME
shm_unlink \- remove a shared memory object (\fBREALTIME\fP)
.SH SYNOPSIS
.LP
\fB#include <sys/mman.h>
.br
.sp
int shm_unlink(const char *\fP\fIname\fP\fB); \fP
\fB
.br
\fP
.SH DESCRIPTION
.LP
The \fIshm_unlink\fP() function shall remove the name of the shared
memory object named by the string pointed to by
\fIname\fP.
.LP
If one or more references to the shared memory object exist when the
object is unlinked, the name shall be removed before
\fIshm_unlink\fP() 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.
.LP
Even if the object continues to exist after the last \fIshm_unlink\fP(),
reuse of the name shall subsequently cause \fIshm_open\fP() to behave
as if no shared memory object of this name exists (that is, \fIshm_open\fP()
will fail if O_CREAT is not set, or will create a new shared memory
object if
O_CREAT is set).
.SH RETURN VALUE
.LP
Upon successful completion, a value of zero shall be returned. Otherwise,
a value of -1 shall be returned and \fIerrno\fP set
to indicate the error. If -1 is returned, the named shared memory
object shall not be changed by this function call.
.SH ERRORS
.LP
The \fIshm_unlink\fP() function shall fail if:
.TP 7
.B EACCES
Permission is denied to unlink the named shared memory object.
.TP 7
.B ENAMETOOLONG
The length of the \fIname\fP argument exceeds {PATH_MAX} or a pathname
component is longer than {NAME_MAX}.
.TP 7
.B ENOENT
The named shared memory object does not exist.
.sp
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
None.
.SH APPLICATION USAGE
.LP
Names of memory objects that were allocated with \fIopen\fP() are
deleted with \fIunlink\fP() in the usual fashion. Names of memory
objects that were allocated with \fIshm_open\fP() are deleted with
\fIshm_unlink\fP(). 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.
.SH RATIONALE
.LP
None.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIclose\fP() , \fImmap\fP() , \fImunmap\fP() , \fIshmat\fP() , \fIshmctl\fP()
, \fIshmdt\fP() , \fIshm_open\fP() , the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<sys/mman.h>\fP
.SH COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 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 .
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