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

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

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

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

     6 <!-- Initial Contributors:

     7     Nokia Corporation - initial contribution.

     8 Contributors: 

     9 -->

    10 <!DOCTYPE concept

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

    12 <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;

    13 #include <sys/mman.h>

    14 #include <fcntl.h>

    15 #include <errno.h>

    16 int main(void)

    17     {

    18     int fd;// File Descriptor

    19     int ret;

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

    21         {

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

    23         }

    24     else

    25         {

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

    27         }

    28     close(fd);//closing the file descriptor

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

    30         {

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

    32         }

    33     else

    34         {

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

    36         }

    37     return ret;

    38     }</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

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

    40                 Shared Memory Object</linktext> </link> <link href="GUID-66402932-5C44-556B-A7AC-1C2D245C8B05.dita"><linktext>Clocks and Timers Tutorial</linktext> </link> </related-links></concept>