<?xml version="1.0" encoding="utf-8"?>

<!-- Copyright (c) 2007-2010 Nokia Corporation and/or its subsidiary(-ies) All rights reserved. -->

<!-- This component and the accompanying materials are made available under the terms of the License 

"Eclipse Public License v1.0" which accompanies this distribution, 

and is available at the URL "http://www.eclipse.org/legal/epl-v10.html". -->

<!-- Initial Contributors:

    Nokia Corporation - initial contribution.

Contributors: 

-->

<!DOCTYPE concept

  PUBLIC "-//OASIS//DTD DITA Concept//EN" "concept.dtd">

<concept xml:lang="en" id="GUID-BE70DCBF-366A-5054-B0F1-7FCEF45FC735"><title>Creating and Unlinking a File Descriptor from a Shared Memory</title><prolog><metadata><keywords/></metadata></prolog><conbody><p>The <xref href="GUID-FF8FD54D-4CD3-3DC7-9A48-56043F26E5DD.dita"><apiname>shm_open()</apiname></xref> function enables you to create shared memory and associate a file descriptor. Use the <xref href="GUID-BF359599-0088-3F3E-BD80-B09C1F5DA380.dita"><apiname>shm_unlink()</apiname></xref> function to remove (unlink a file descriptor from a shared memory) the name of the shared memory object. </p> <p>Example: </p> <codeblock id="GUID-F030E460-536D-53A8-86F1-36E63860677D" xml:space="preserve">#include &lt;stdio.h&gt;

#include <sys/mman.h>

#include <fcntl.h>

#include <errno.h>

int main(void)

    {

    int fd;// File Descriptor

    int ret;

    if((fd = shm_open("page", O_RDWR|O_CREAT, 0666)) < 0)

        {

        printf("Shared memory creation failed with errno %d\n", errno);

        }

    else

        {

        printf("Shared memory creation was successful\n");

        }

    close(fd);//closing the file descriptor

    if((ret = shm_unlink("page")) < 0) 

        {

        printf("Shared memory unlinking failed with errno %d\n", errno);

        }

    else

        {

        printf("Shared memory unlinking was successful\n");

        }

    return ret;

    }</codeblock> </conbody><related-links><link href="GUID-9AC6774A-41E9-5298-8696-0A317A09E1E9.dita"><linktext>Librt Overview</linktext> </link> <link href="GUID-A4ECB450-02DA-5E85-91AC-4C8BDE0B9B58.dita"><linktext>Writing, Reading and Seeking from a

                Shared Memory</linktext> </link> <link href="GUID-8F6D6934-8FF0-5045-8AB1-74384BE792EA.dita"><linktext>Retrieving Information about a