Randolph J Tata

Talcon Information Systems

v1.40 2002/01/10

Revision History
Revision v1.402002-01-10rjt
Added description and link to cdtower shell script.
Revision v1.302002-01-08rjt
Many additions and changes to markup in DocBook XML source and fix pubdate data.
Revision v1.012002-01-07rjt
Updated for 2.4 kernels. Added more References and links. Convert to DocBook XML 4.1.2 Change License from LDP boilerplate to GFDL.
Revision v1.002000-09-23rjt
Conversion from Linuxdoc SGML to DocBook v3.1 SGML
Revision v0.102000-09-01rjt
Conversion to Linuxdoc SGML from text/html, added kerneltweak (addloops) section
Revision v0.012000-08-18rjt
First version released in text and html.


The CD Server HOWTO describes the steps and commands you can use to setup your own CD Server using Linux and some built-in Unix commands along with other freely available software packages. The CD Server can then share the CD's via the network to Windows and/or other client machines.

Table of Contents

1. Introduction
1.1. Intended Audience
1.2. Things You'll Need
1.3. Suggested Reading and References
1.4. Copyright and License
1.5. Disclaimer
1.6. News
1.7. Credits
1.8. Translations
2. Procedure
2.1. Creating the ISO Images
2.2. Mounting the ISO Images
2.3. Mounting the Image upon System Restart
2.4. Sharing it on a Windows Network using Samba
2.5. Sharing the Images on a Unix network using NFS
3. Adding Support for More Loop Devices
3.1. Adding the Loop Module Option
3.2. Appending to the Boot Prompt
3.3. Tweaking the Kernel
3.4. Creating the Loop Devices in /dev
4. More Information
4.1. Frequently Asked Questions
4.2. Other Instructions Available on the Web
4.3. Under Future Consideration
A. GNU Free Documentation License
How to use this License for your documents

1. Introduction

With disk space becoming less expensive (100GB Western Digital 7200rpm available for US $195 in January 2002), it is viable to use an Open Source software-based CD Server solution, instead of paying $800-$4,000 for a software, thin-server, or CD Jukebox solution.

I've setup my CD Server on a Pentium 200 with 64MB RAM, using one of these large drives.

Any comments, suggestions, additions, or corrections can be sent to my email address at Talcon Information Systems: .

1.1. Intended Audience

This HOWTO is specifically directed toward System Administrators and uses Linux for the examples. It should work with other flavors of Unix provided that they have a loop device or a method of mounting a CD image file within the directory tree as a block device using the iso9660 file system.

1.2. Things You'll Need

The commands and utilities needed to setup your own CD Server are already included in most (if not all) Linux distributions.

  • A Linux Distribution (This HOWTO uses Linux-Mandrake for the examples)

  • dd - Converts and copies a file (a standard Unix command)

  • mount - Mounts and Unmounts filesystems (a standard Unix command)

  • Samba - A Windows SMB/CIFS fileserver for Unix

  • NFS (optional for Unix) - Network File System (included in Linux distributions)

  • Netatalk (optional for Macs) - A package that lets a Unix machine supply Appletalk print and file services on a LAN.


Previous to the 2.4 kernels, the Linux-Mandrake distribution I was using only had support for 8 loop devices compiled into the kernel (see Section 3, “Adding Support for More Loop Devices ” to increase this number). At that time, you were only be able to share 8 CD's on a network with that default value, and to share more than 8, the loop block driver source code (loop.c) needed to be modified and a new kernel compiled.

With the 2.4 kernels, that is no longer required. You can now set the number of loop devices dynamically via the max_loop module parameter, or by passing max_loop=[1-255] to the kernel on boot.

1.3. Suggested Reading and References

SMB HOWTO by: David Wood, dwood (at) Part of the Linux Documentation Project. This document describes how to use the Server Message Block (SMB) protocol, also called the Session Message Block, NetBIOS or LanManager protocol, with Linux using Samba.

Using Samba by: Robert Eckstein, David Collier-Brown, Peter Kelly 1st Edition November 1999, O'Reilly and Associates, Inc. ISBN 1-56592-449-5,

The Linux CD-ROM HOWTO by: Jeff Tranter, tranter (at) Part of the Linux Documentation Project. How to install, configure, and use CD-ROM drives under Linux. It lists the supported hardware and answers a number of frequently asked questions. This HOWTO also gives some information on using multi-platter CD-ROM drives with Linux.

CD-Writing HOWTO by: Winfried Trümper, winni (at) Part of the Linux Documentation Project. This document explains how to write CD-ROMs under Linux. This HOWTO also includes information on making 1:1 image copies of CD-ROMs.

1.4. Copyright and License

CDServer-HOWTO™, Copyright © 2000-2002, by Randolph J. Tata, All Rights Reserved

Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with no Invariant Sections, no Front-Cover Texts and no Back-Cover Texts. A copy of the license is included in Appendix A, GNU Free Documentation License entitled "GNU Free Documentation License".

1.5. Disclaimer

Use the information in this document at your own risk. I disavow any potential liability for the contents of this document. Use of the concepts, examples, and/or other content of this document is entirely at your own risk.

All copyrights are owned by their owners, unless specifically noted otherwise. Use of a term in this document should not be regarded as affecting the validity of any trademark or service mark.

Naming of particular products or brands should not be seen as endorsements.

You are strongly recommended to make a backup of your system before major installation and should make backups at regular intervals.

1.6. News

As always, check the revision history at the top of this document.

DocBook XML source for this document is available. Any additions/changes should be made to the DocBook XML source, not derivative formats.

This documents home page is at the CDServer-HOWTO site page in case you need the latest version, or there is a problem with the page format you are viewing.

1.7. Credits

My thanks go the readers of this HOWTO and those willing to share their experiences and knowledge with me. I have the pleasure of acknowledging:

Mark F. Komarinskimarkk (at) linuxdoc.orgLDP Author Guide
Jorge Godoygodoy (at) metalab.unc.eduLDP Author Guide
David C. Merrilldcmerrill (at) mindspring.comLDP Author Guide
Stein Gjoensgjoen (at) nyx.netHOWTO-Template
Gregory Leblancgleblanc (at) cu-portland.eduHOWTO-Template
Greg Fergusongferg (at) sgi.comHOWTO-Template
Amar Chaoucheachaouche (at) linbox.commount unhide option
Giblhauser Carl Michaelmike (at) bawb.bmlf.gv.atrunoutblock i/o errors
Monte Milanukmilanuk (at) yahoo.comnfs help
Paul A. Sandpas (at) unh.eduloop module option max_loop
Tony MeliaTony.Melia (at) kernel boot parameter
Richard BlackRichard.Black (at) compaq.commore info and mknod script
Bradley Wendelboekrakken (at) icehouse.2y.netcdtower shell script
James Mummdart (at) windeath.2y.netcdtower shell script

1.8. Translations

If you have the capacity it would be nice to make the CDServer-HOWTO available in a number of formats and languages.

If you've translated this document, please send to me:

  • Your name, email address, the language and URL to the translated document (preferred).

  • Or an email attachment of the work.

Please send either to my email address at Talcon Information Systems: .

2. Procedure

Summary of Steps

  • Create a large partition to hold the CD Image Files.

  • Copy the CD to an image file using the dd command.

  • Mount the CD image file within the directory tree.

  • Share the directory on the network using Samba, NFS, etc.

Also, make sure you've read Section 1, “Introduction” and Section 1.2, “Things You'll Need”.

2.1. Creating the ISO Images

Choose (or create) a file system with the largest available disk space on it. Keep in mind that CD-ROM's can hold around 640MB of data, so if you want to share 8 full CD's on your network, you'll need 5.1GB of space available.

Login as root or "su" to root.

bash# df -h

Filesystem            Size  Used Avail Use% Mounted on
/dev/hda5             1.4G   82M  1.3G   6% /
/dev/hda1              15M  827k   14M   6% /boot
/dev/hda7             2.4G 1008M  1.3G  43% /usr
/dev/hda8            23.6G 11.7G 11.7G  50% /home

Here the /home filesystem has the most available space, so it is the most suitable filesystem to use for dumping the CD images to.

bash# cd /home
bash# mkdir image
bash# cd image

Now, copy the CD to an ISO image. You must know the device name of your CD-ROM drive (usually /dev/cdrom, it could be /dev/scd0 for SCSI CD-ROM's) I'll use the Mandrake distribution CD-ROM as an Example:

bash# dd if=/dev/cdrom of=mndrk81.iso


The if= is the input file, the of= is the output file. You should see a message stating the number of records in and number of records out.

If you see i/o errors, they will most likely be due to the lead-in and lead-out runoutblocks on the CD. If the number of records in and number of records out do not match you may have a problem, otherwise the image will most likely be alright, but you can never know if the errors happened while reading the ISO part of the CD or not (due to dust or scratches on the CD).

Other utilities to read CD's exist, like readcd or sdd.

More information about making 1:1 copies of CD's exists in the [CD-Writing-HOWTO], see Section 1.3, “Suggested Reading and References”.

My thanks to Giblhauser Carl Michael for the runoutblock information.

2.2. Mounting the ISO Images

The next step is to mount the ISO image file. Let's create a directory under /mnt to place the mounted file.

bash# cd /mnt
bash# mkdir iso
bash# cd iso
bash# mkdir mndrk81

Now mount the ISO image file to this newly created directory

bash# mount -o loop,unhide -t iso9660 -r /home/image/mndrk81.iso /mnt/iso/mndrk81


The -o loop means use the option that mounts a file as a block device. The unhide option shows hidden files. The -t iso9660 means that the file is in the iso9660 CD-ROM format. The -r means to mount read-only.

Thanks to Amar Chaouche for pointing out the unhide option for the mount command.

Now you can:

bash# cd mndrk81
bash# ls -al

You should see a listing (ls) of the files and directories that are on the actual CD (only now they're inside the ISO image file, and that's what you're currently looking at!)

2.3. Mounting the Image upon System Restart

Now that we've manually mounted the image, and made sure it works, an entry needs to made in the /etc/fstab file so that the image is remounted on the next system startup. It's important to make the entry AFTER the entry for the parent filesystem, e.g. /home (I use vim, but emacs, joe, pico or jed will work just as well):

bash# vim /etc/fstab

After the line that looks like the following (or whichever filesystem you've placed your images):

/dev/hda8 /home ext2 defaults 1 2

Insert the following line with your text editor:

/home/image/mndrk81.iso /mnt/iso/mndrk81 iso9660 ro,loop,auto,unhide 0 0

2.4. Sharing it on a Windows Network using Samba

You'll need to have Samba installed and working to perform the next steps (that's outside the scope of this instruction, see Section 1.3, “Suggested Reading and References”). If it's not yet installed, consult your Linux distribution's instructions for installing the Samba package. Or you can visit the Samba website at for installation instructions, binaries, and/or the source code.

To share your mounted CD's on a windows network, simply create a stanza in the /etc/smb.conf file similar to the following:

  comment = All Shared CD Images
  path = /mnt/iso
  public = yes
  writable = no

This will share all the subdirectories under the /mnt/iso directory on the network. To mount the share to a local drive (in this case the I: drive), bring up an MS-DOS Prompt on the Windows machine and type the following:

C:\> net use I: \\yourlinuxmachine\cdimages

Each CD image will now appear as a subdirectory on the I: drive of your Windows machine.

To mount ONLY the Mandrake CD image to a drive letter (we'll use M:, the root drive of which, will correspond exactly to the CD as if it was just inserted in the CD-ROM drive), create the following stanza in the /etc/smb.conf file.

  comment = Mandrake Linux 8.1
  path = /mnt/iso/mndrk81
  public = yes
  writable = no

Then, at your MS-DOS Prompt, mount it with the following command:

C:\> net use m: \\yourlinuxmachine\mndrk81


The Samba smb.conf file stanzas presented here are simplified, and not secure. Many more options exist for a Samba share which limit who can mount the shares, control how user authentication is performed, and whether the share is even browseable through Network Neighborhood on the Windows machines.

2.5. Sharing the Images on a Unix network using NFS

Make sure that NFS is running and configured correctly on your Linux machine, then add the following to the /etc/exports file using your own preferred options:

# sample /etc/exports file
       /mnt/iso            (ro,insecure,nohide,all_squash)


The nohide option will allow you to mount a parent directory, without explicitly mounting all exported subdirectories beneath it.

Now try running:

bash# exportfs -r

This should re-export everything in your /etc/exports file.

Now, when typing showmount -e yourlinuxmachine you should see that the /mnt/iso directory is included in the exports list.

3. Adding Support for More Loop Devices

Newer Linux kernels (2.4) allow you to add more loop devices easily by editing /etc/modules.conf or through the use of a boot parameter.

Older kernels (2.2 ?) only had support for 8 loop devices compiled into the kernel. In short, you were only able to share 8 CD's on a network with this default value. In order to support more than that default, you needed to modify the kernel source and recompile a new kernel.

Use the following methods to determine which version of the kernel you are running.

bash# uname -a


bash# cat /proc/version

3.1. Adding the Loop Module Option

Current kernels allow you to set the number of loop devices supported without recompiling the kernel. One of these methods is to add an options line to /etc/modules.conf. This method will only work if your loop support has been configured as a loadable kernel module (which is how most major Linux distributions come preconfigured now).

Edit /etc/modules.conf and add the following line.

options loop max_loop=64

After making the above change, simply reboot. Or you can try to use rmmod and insmod to make the change on the fly - but this will not work if you currently have any loop devices mounted (you'll get an error saying loop: Device or resource busy).


If you do not have an /etc/modules.conf file, your module configuration file may be called /etc/conf.modules (this name is now deprecated).

Continue with Section 3.4, “Creating the Loop Devices in /dev”.

Thanks to Paul A. Sand for pointing out the /etc/modules.conf option.

3.2. Appending to the Boot Prompt

If your loop support has been compiled directly into the kernel (in other words, it is not loaded as a module), you can append the number of loop devices you would like to support at the linux boot prompt.

boot:  linux max_loop=64

Or, if you are using LILO, you can edit your linux boot stanza in /etc/lilo.conf and add/modify the append= line. Here is an example stanza showing append= (note: only add or modify the append line, don't change your whole stanza to look like this one or your system may not boot). For more information about LILO, consult the LILO mini-HOWTO at


	append=" max_loop=64"


After changing /etc/lilo.conf, you need to run the lilo command for your changes to take effect.

bash# lilo

Added linux *
Added linux-nonfb
Added failsafe
Added windows
Added floppy

Next restart your system. After your system restarts, you can check your boot command line by typing the following:

bash# cat /proc/cmdline


I am not sure if the loop module (compiled as a module) reads /proc/cmdline when the module is loaded, and therefore may not need an options line /etc/modules.conf. It's possible that it can (and if it doesn't, it should). To summarize: I have not tested this.

Continue with Section 3.4, “Creating the Loop Devices in /dev”.

Thanks to Tony Melia for the boot prompt info.

3.3. Tweaking the Kernel

If you have an older kernel (v. 2.2) or if you are completely comfortable recompiling the kernel, you can increase the number of loop devices supported by editing the /usr/src/linux/drivers/block/loop.c file.


If you find that the kernel sources are not installed on your machine, you'll need to consult your Linux Distribution's documentation on how to install them (the Kernel Sources come with all distributions - it's part of the GNU GPL licensing).

Change the number in the following line to however many loop devices you'll need.

#define MAX_LOOP 16

Compile the new kernel or module as the case may be. If you need some help getting started with this, read /usr/src/linux/README or consult The Linux Kernel HOWTO.

Continue with Section 3.4, “Creating the Loop Devices in /dev”.

3.4. Creating the Loop Devices in /dev

You should check how many /dev entries you have for loop devices.

bash# ls -l /dev/loop*

The mknod command creates the devices in the /dev directory. The loop devices have a major number of 7, and the minor numbers begin at 0. If your MAX_LOOP was defined as 8 in /usr/src/linux/drivers/block/loop.c, you should have /dev/loop0 through /dev/loop7. To create the /dev/loop8 device, use the following command (subsitute the appropriate number you need for both the 8's in the example below).

bash# mknod -m660 /dev/loop8 b 7 8

Check Owner/Group & Permissions on the new file (using ls -l). You can change the owner and group with the following command:

bash# chown root.disk /dev/loop8

You can change the permissions using the following command:

bash# chmod 666 /dev/loop8

4. More Information

Be sure to check the suggested reading in Section 1.3, “Suggested Reading and References”.

4.1. Frequently Asked Questions

I finally had to create this section - Frequently Asked Questions. Although, I sometimes think it should be called Frequently Answered Questions (at least I try to answer them all).

Q: Can I copy CD contents to a directory and share it with SAMBA?
Q: Do any scripts or programs exist that automate this process?
Q: Do any web interfaces exist that automate this process?
Q: Can copy-protected CD's (e.g. laserlok) be shared in this way?


Can I copy CD contents to a directory and share it with SAMBA?


In a word - Yes.

There is nothing to keep you from doing that. However I'm not sure which arguments you would have to use with tar and which options to include in the SAMBA stanzas. Also, there could be problems with file name mangling (case sensitivity, spaces in file names), file attributes (read-only), etc. If anyone is doing this successfully, please send me examples of the commands you used for copying the contents of the CD, and your SAMBA stanzas for the shares.

Here's some commands you can use to copy the contents:

bash# cd /home
bash# mkdir image
bash# cd image
bash# mkdir mndrk81
bash# mount /mnt/cdrom
bash# cd /mnt/cdrom
bash# tar cvf - . | (cd /home/image/mndrk81; tar xvf -)

Thanks to Giblhauser Carl Michael for this info


Do any scripts or programs exist that automate this process?



  • Bradley Wendelboe and James Mumm wrote a shell script called CDTower - see Section 4.2.2, “CDTower v.06” to download it.

    I have no independent test results of this script - use at your own risk.


Do any web interfaces exist that automate this process?


Not yet. However there is much interest in this.

  • Tony Melia [Tony.Melia (at)] has announced that he is 60% complete with a web interface, i.e. sucking CD's in, creating extra /dev/loop entries and seeing what space the CD's are taking up.

  • I am planning on writing a module for Webmin to automate this process. That project is currently hosted on SourceForge at


Can copy-protected CD's (e.g. laserlok) be shared in this way?


To the best of my knowledge, No.

Others have reported problems to me trying to share ISO images made from copy-protected CD's. It seems that even when using the unhide option with mount that files will remain hidden.

4.2. Other Instructions Available on the Web

This section is devoted to instructional materials that others have written or have sent to me.

4.2.1. Saving a CD-ROM to a File and Mounting it

Richard Black (Compaq) has some good pages about Saving CD-ROM's to files and mounting them in Red Hat Linux.

Device nodes are required to access the loop devices. You already have loop0 - loop7.
You can run the following loop to create the rest of the nodes (loop8 - loop255).
You can type all of the following lines of code on one single line if you leave off 
the trailing "\" characters.

C=8; echo; echo "Creating loop device nodes."; \
   while [ $C -lt 256 ]; do mknod /dev/loop$C b 7 $C; \
   echo -n .; C=`expr $C + 1`; done; echo;

Note: the quoting around the expr section are called backtick's and they are located
with the tilde character ("~") in the upper left hand corner of the keyboard. The 
character is not a single quote.

Thanks to Richard Black for permission to add this info and for linking back to this document.

4.2.2. CDTower v.06

A script to automate the creation of ISO images and share them via Samba

by Bradley Wendelboe [krakken (at)] and James Mumm [dart (at)]

This software is covered under the GPL See for details.


I have no independent test results of this script - use at your own risk.

Thanks to Bradley Wendelboe for forwarding this script to me.

4.3. Under Future Consideration

These are things I'm currently looking into, trying to figure out, or planning to get done.

  • Make more scripts available that others have sent to me, either within this howto, or by hosting them and linking to them from this document.

  • Sharing CD's to Apple and Netware clients (Appletalk and IPX).

  • Compressed ISO Images.

  • Changing CD Shares on the fly (hopefully transparent to users).

  • Adding a module to Webmin to automate the CDServer process.

  • Distribution specific instructions.

  • I have a volunteer for a German translation, hopefully it will be done soon.

A. GNU Free Documentation License

Version 1.1, March 2000

Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.


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This License is a kind of "copyleft", which means that derivative works of the document must themselves be free in the same sense. It complements the GNU General Public License, which is a copyleft license designed for free software.

We have designed this License in order to use it for manuals for free software, because free software needs free documentation: a free program should come with manuals providing the same freedoms that the software does. But this License is not limited to software manuals; it can be used for any textual work, regardless of subject matter or whether it is published as a printed book. We recommend this License principally for works whose purpose is instruction or reference.


This License applies to any manual or other work that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. The "Document", below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as "you".

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  7. Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document's license notice.

  8. Include an unaltered copy of this License.

  9. Preserve the section entitled "History", and its title, and add to it an item stating at least the title, year, new authors, and publisher of the Modified Version as given on the Title Page. If there is no section entitled "History" in the Document, create one stating the title, year, authors, and publisher of the Document as given on its Title Page, then add an item describing the Modified Version as stated in the previous sentence.

  10. Preserve the network location, if any, given in the Document for public access to a Transparent copy of the Document, and likewise the network locations given in the Document for previous versions it was based on. These may be placed in the "History" section. You may omit a network location for a work that was published at least four years before the Document itself, or if the original publisher of the version it refers to gives permission.

  11. In any section entitled "Acknowledgements" or "Dedications", preserve the section's title, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.

  12. Preserve all the Invariant Sections of the Document, unaltered in their text and in their titles. Section numbers or the equivalent are not considered part of the section titles.

  13. Delete any section entitled "Endorsements". Such a section may not be included in the Modified Version.

  14. Do not retitle any existing section as "Endorsements" or to conflict in title with any Invariant Section.

If the Modified Version includes new front-matter sections or appendices that qualify as Secondary Sections and contain no material copied from the Document, you may at your option designate some or all of these sections as invariant. To do this, add their titles to the list of Invariant Sections in the Modified Version's license notice. These titles must be distinct from any other section titles.

You may add a section entitled "Endorsements", provided it contains nothing but endorsements of your Modified Version by various parties--for example, statements of peer review or that the text has been approved by an organization as the authoritative definition of a standard.

You may add a passage of up to five words as a Front-Cover Text, and a passage of up to 25 words as a Back-Cover Text, to the end of the list of Cover Texts in the Modified Version. Only one passage of Front-Cover Text and one of Back-Cover Text may be added by (or through arrangements made by) any one entity. If the Document already includes a cover text for the same cover, previously added by you or by arrangement made by the same entity you are acting on behalf of, you may not add another; but you may replace the old one, on explicit permission from the previous publisher that added the old one.

The author(s) and publisher(s) of the Document do not by this License give permission to use their names for publicity for or to assert or imply endorsement of any Modified Version.


You may combine the Document with other documents released under this License, under the terms defined in section 4 above for modified versions, provided that you include in the combination all of the Invariant Sections of all of the original documents, unmodified, and list them all as Invariant Sections of your combined work in its license notice.

The combined work need only contain one copy of this License, and multiple identical Invariant Sections may be replaced with a single copy. If there are multiple Invariant Sections with the same name but different contents, make the title of each such section unique by adding at the end of it, in parentheses, the name of the original author or publisher of that section if known, or else a unique number. Make the same adjustment to the section titles in the list of Invariant Sections in the license notice of the combined work.

In the combination, you must combine any sections entitled "History" in the various original documents, forming one section entitled "History"; likewise combine any sections entitled "Acknowledgements", and any sections entitled "Dedications". You must delete all sections entitled "Endorsements."


You may make a collection consisting of the Document and other documents released under this License, and replace the individual copies of this License in the various documents with a single copy that is included in the collection, provided that you follow the rules of this License for verbatim copying of each of the documents in all other respects.

You may extract a single document from such a collection, and distribute it individually under this License, provided you insert a copy of this License into the extracted document, and follow this License in all other respects regarding verbatim copying of that document.


A compilation of the Document or its derivatives with other separate and independent documents or works, in or on a volume of a storage or distribution medium, does not as a whole count as a Modified Version of the Document, provided no compilation copyright is claimed for the compilation. Such a compilation is called an "aggregate", and this License does not apply to the other self-contained works thus compiled with the Document, on account of their being thus compiled, if they are not themselves derivative works of the Document.

If the Cover Text requirement of section 3 is applicable to these copies of the Document, then if the Document is less than one quarter of the entire aggregate, the Document's Cover Texts may be placed on covers that surround only the Document within the aggregate. Otherwise they must appear on covers around the whole aggregate.


Translation is considered a kind of modification, so you may distribute translations of the Document under the terms of section 4. Replacing Invariant Sections with translations requires special permission from their copyright holders, but you may include translations of some or all Invariant Sections in addition to the original versions of these Invariant Sections. You may include a translation of this License provided that you also include the original English version of this License. In case of a disagreement between the translation and the original English version of this License, the original English version will prevail.


You may not copy, modify, sublicense, or distribute the Document except as expressly provided for under this License. Any other attempt to copy, modify, sublicense or distribute the Document is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance.


The Free Software Foundation may publish new, revised versions of the GNU Free Documentation License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. See

Each version of the License is given a distinguishing version number. If the Document specifies that a particular numbered version of this License "or any later version" applies to it, you have the option of following the terms and conditions either of that specified version or of any later version that has been published (not as a draft) by the Free Software Foundation. If the Document does not specify a version number of this License, you may choose any version ever published (not as a draft) by the Free Software Foundation.

. How to use this License for your documents

To use this License in a document you have written, include a copy of the License in the document and put the following copyright and license notices just after the title page:

Copyright (c) YEAR YOUR NAME. Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.1 or any later version published by the Free Software Foundation; with the Invariant Sections being LIST THEIR TITLES, with the Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A copy of the license is included in the section entitled "GNU Free Documentation License".

If you have no Invariant Sections, write "with no Invariant Sections" instead of saying which ones are invariant. If you have no Front-Cover Texts, write "no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise for Back-Cover Texts.

If your document contains nontrivial examples of program code, we recommend releasing these examples in parallel under your choice of free software license, such as the GNU General Public License, to permit their use in free software.