rcirc Manual
rcirc is an Emacs IRC client.
IRC (Internet Relay Chat) is a multi-user chat protocol. Users communicate with each other in real-time. Communication occurs both in topic channels which are collections of many users, or privately, with just one other user.
Copyright © 2006–2024 Free Software Foundation, Inc.
Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1.3 or any later version published by the Free Software Foundation; with no Invariant Sections, with the Front-Cover Texts being “A GNU Manual”, and with the Back-Cover Texts as in (a) below. A copy of the license is included in the section entitled “GNU Free Documentation License”.
(a) The FSF’s Back-Cover Text is: “You have the freedom to copy and modify this GNU manual.”
Table of Contents
1 Basics
This chapter contains a brief introduction to IRC (Internet Relay Chat),
and a quick tutorial on rcirc.
1.1 Internet Relay Chat
Internet Relay Chat (IRC) is a form of instant communication over the Internet. It is mainly designed for group (many-to-many) communication in discussion forums called channels, but also allows one-to-one communication.
Contrary to most Instant Messenger (IM) systems, users usually don’t connect to a central server. Instead, users connect to a random server in a network, and servers relay messages from one to the next.
Here’s a typical example:
When you connect to the Libera.Chat network
(https://libera.chat), you point your IRC client at the
server irc.libera.chat. That server will redirect your client
to a random server on the network, such as
zirconium.libera.chat.
Once you’re connected, you can send messages to all other users
connected to the same network, and you can join all channels on the same
network. You might join the #emacs and the #rcirc
channels, for example. (Typically, channel names begin with a hash
character.)
Once you have joined a channel, anything you type will be broadcast to all the other users on the same channel.
If you want to address someone specifically, for example as an answer to a question, it is customary to prefix the message with the nick followed by a colon, like this:
deego: fsbot rules!
Since this is so common, you can use TAB to do nick completion.
By default rcirc will use the default completion system, but you can
enable rcirc-cycle-completion-flag to cycle nicks in place.
1.2 Getting started with rcirc
Use the command M-x irc to connect using the defaults. See Configuration, if you want to change the defaults.
Use C-u M-x irc if you don’t want to use the defaults, e.g., if you want to connect to a different network, or connect to the same network using a different nick. This will prompt you for four things:
- IRC Server
What server do you want to connect to? All the servers in a particular network are equivalent. Some networks use a round-robin system where a single server redirects new connections to a random server in the network.
irc.libera.chatis such a server for the Libera.Chat network. Libera.Chat’s purpose is “to provide services such as a community platform for free open-source software and peer directed projects on a volunteer basis,” and was chosen as the official home of the GNU Project and the Free Software Foundation’s IRC channels in June 2021 in the aftermath of the changes in governance and policies of the Freenode IRC network. GNU and FSF’s announcements about this are at https://lists.gnu.org/archive/html/info-gnu/2021-06/msg00005.html, https://lists.gnu.org/archive/html/info-gnu/2021-06/msg00007.html, and https://lists.gnu.org/archive/html/info-gnu-emacs/2021-06/msg00000.html.- IRC Port
All network connections require a port. Just as web servers and clients use port 80 per default, IRC uses port 6667 per default. You rarely have to use a different port.
- IRC Nick ¶
Every users needs a handle on-line. You will automatically be assigned a slightly different nick if your chosen nick is already in use. If your
user-login-nameisalex, and this nick is already in use, you might for example get assigned the nickalex`.- IRC Channels
A space separated list of channels you want to join when connecting. You don’t need to join any channels, if you just want to have one-to-one conversations with friends on the same network. If you’re new to the Libera.Chat network, join
#emacs, the channel about all things Emacs, or join#rcirc, the channel aboutrcirc.
When you have answered these questions, rcirc will create a server
buffer, which will be named something like *irc.libera.chat*,
and a channel buffer for each of the channels you wanted to join.
To talk in a channel, just type what you want to say in a channel buffer, and press RET.
If you want to paste multiple lines, such as source code, you can use C-c C-c to edit your message in a separate buffer. Use C-c C-c to finish editing. You still need to press RET to send it, though. Generally, IRC users don’t like people pasting more than around four lines of code, so use with care.
Once you are connected to multiple channels, or once you’ve turned you attention to other buffers in Emacs, you probably want to be notified of any activity in channels not currently visible. All you need to do is switch channel tracking on using M-x rcirc-track-minor-mode. To make this permanent, add the following to your init file:
(rcirc-track-minor-mode 1)
Use C-c C-SPC to switch to these buffers.
If the user wishes to ignore events in the server buffer, set
rcirc-track-ignore-server-buffer-flag to a non-nil value.
2 Reference
This is the reference section of the manual. It is not complete. For
complete listings of rcirc features, use Emacs built-in
documentation.
2.1 rcirc commands
This is a list of commands that you may use in rcirc. It is not
complete. For a complete listing, press C-h m in an rcirc
buffer.
In addition to using regular Emacs key bindings, you can call them by
typing them into an rcirc buffer.
For instance, instead of using the command C-c C-j to join a new
channel, you may type this in an rcirc buffer, and press RET:
/join #emacs
This is why you cannot start a message with a slash. You will have to precede the command with a space, or rewrite your message in order to send it to a channel.
Many commands take parameters. IRC commands usually ignore string delimiters. Neither apostrophe nor double-quote have special meanings in IRC.
/nick "alex schroeder"
This will try to change your nick to "alex. Usually this will
fail because the double quote character is not a valid character for
nicks.
These commands are case insensitive.
If a command isn’t known by rcirc, it will simply be sent along to the
server. There is a list of some useful commands like that in the next
section.
- C-c C-j ¶
-
This joins a channel such as
#rcircor#emacs. On most networks, anybody can create new channels. If you want to talk with some friends, for example, all you have to do is agree on a valid channel name and join that channel. (Also/join #emacs.) - C-c C-p ¶
-
This leaves the current channel. You can optionally provide a different channel name and reason for parting. When you kill a channel buffer, you automatically part the corresponding channel. (Also
/part #emacs you are too weird!.) - C-c C-r ¶
-
This changes your nick to some other name. Your nick must be unique across the network. Most networks don’t allow too many nick changes in quick succession, and have restrictions on the valid characters in nick names. (Also
/nick alex-test) - C-c C-w ¶
-
Gives you some basic information about a nick. This often includes what other channels people are on. (Also
/whois fsbot.) - C-c C-q ¶
-
Starts a one-to-one conversation with another person on the same network. A new buffer will be created for this conversation. It works like a channel with only two members. (Also
/query fsbot.) - C-c RET ¶
-
This sends a single message to a nick. Like with C-c C-q, a new buffer is created, where the response from the other party will show up. (Also
/msg nickserv identify secret.) - C-c C-x ¶
-
This disconnects from the server and parts all channels. You can optionally provide a reason for quitting. When you kill the server buffer, you automatically quit the server and part all channels. (Also
/quit ZZZzzz....) - /reconnect ¶
-
This reconnects after you have lost the connection.
If you’re chatting from a laptop, then you might be familiar with this problem: When your laptop falls asleep and wakes up later, your IRC client doesn’t realize that it has been disconnected. It takes several minutes until the client decides that the connection has in fact been lost. The simple solution is to use M-x rcirc. The problem is that this opens an additional connection, so you’ll have two copies of every channel buffer, one dead and one live.
One option therefore, is the
/reconnectcommand.An other approach is to set
rcirc-reconnect-delayto a value greater than 0, and allow rcirc to reconnect when it detects that the connection has been closed. By default it will try to do this three times (as specified byrcirc-reconnect-attempts), before giving up.
2.2 Useful IRC commands
As mentioned, if a command isn’t known by rcirc, it will simply be sent
along to the server. Some such commands are available on nearly all IRC
servers, such as:
/away¶-
This sets your status as “being away” if you provide a reason, or sets your status as “being back” if you do not. People can use the C-c C-w command to check your status. Example:
/away food.
Typical IRC servers implement many more commands. You can read more about the fantastic world of IRC online at the Internet Relay Chat (IRC) help archive.
2.3 Configuration
These are some variables you can change to configure rcirc to your
liking.
rcirc-server-alist¶-
This variable contains an alist of servers to connect to by default and the keywords parameters to use. The keyword parameters are optional. If you don’t provide any, the defaults as documented below will be used.
The most important parameter is the
:channelsparameter. It controls which channels you will join by default as soon as you are connected to the server.Here’s an example of how to set it:
(add-to-list 'rcirc-server-alist '("otherworlders.org" :channels ("#FUDGE" "#game-design")))By default you will be connected to the
rcircsupport channel:#rcirconirc.libera.chat.:nickThis overrides
rcirc-default-nick.:portThis overrides
rcirc-default-port.:user-nameThis overrides
rcirc-default-user-name.:full-nameThis overrides
rcirc-default-full-name.:channelsThis describes which channels to join when connecting to the server. If absent, no channels will be connected to automatically.
rcirc-default-nick¶This variable is used for the default nick. It defaults to the login name returned by
user-login-name.(setopt rcirc-default-nick "kensanata")
rcirc-default-port¶-
This variable contains the default port to connect to. It is 6667 by default and rarely needs changing.
rcirc-default-user-name¶-
This variable contains the default user name to report to the server. It defaults to the login name returned by
user-login-name, just likercirc-default-nick. rcirc-default-full-name¶-
This variable is used to set your “real name” on IRC. It defaults to the name returned by
user-full-name. If you want to hide your full name, you might want to set it to some pseudonym.(setopt rcirc-default-full-name "Curious Minds Want To Know")
rcirc-authinfo¶-
This variable is an alist used to automatically identify yourself on networks. Each sublist starts with a regular expression that is compared to the server address you’re connecting to. The second element in the list is a symbol representing the method to use, followed by the arguments this method requires.
Here is an example to illustrate how you would set it:
(setopt rcirc-authinfo '(("Libera.Chat" nickserv "bob" "p455w0rd") ("Libera.Chat" chanserv "bob" "#bobland" "passwd99") ("bitlbee" bitlbee "robert" "sekrit")))And here are the valid method symbols and the arguments they require:
nickserv¶Use this symbol if you need to identify yourself as follows when connecting to a network:
/msg nickserv identify secret. The necessary arguments are the nickname you want to use this for, and the password to use.Before you can use this method, you will have to register your nick and pick a password for it. Contact
nickservand check out the details. (Using/msg nickserv help, for example.)chanserv¶Use this symbol if you need to identify yourself as follows if you want to join a particular channel:
/msg chanserv identify #underground secret. The necessary arguments are the nickname and channel you want to use this for, and the password to use.Before you can use this method, a channel contact must tell you about the password to use. Contact
chanservand check out the details. (Using/msg chanserv help, for example.)bitlbee¶Use this symbol if you need to identify yourself in the Bitlbee channel as follows:
identify secret. The necessary arguments are the nickname you want to use this for, and the password to use.Bitlbee acts like an IRC server, but in fact it is a gateway to a lot of other instant messaging services. You can either install Bitlbee locally or use a public Bitlbee server. There, you need to create an account with a password. This is the nick and password you need to provide for the bitlbee authentication method.
Later, you will tell Bitlbee about your accounts and passwords on all the other instant messaging services, and Bitlbee will log you in. All
rcircneeds to know, is the login to your Bitlbee account. Don’t confuse the Bitlbee account with all the other accounts.sasl¶Use this symbol if you want to use SASL authentication. The necessary arguments are the nickname you want to use this for, and the password to use.
certfp¶Use this symbol if you want to use CertFP authentication. The necessary arguments are the path to the key and to the client certificate associated with the account. The CertFP authentication requires a TLS connection.
3 Fighting Information Overload
This is the section of the manual that caters to the busy person
online. There are support channels with several hundred people in
them. Trying to follow a conversation in these channels can be a
daunting task. This chapters tells you how rcirc can help.
3.1 Channels
Most people want a notification when something is said on a channel they have joined, particularly if they have been addressed directly. There is a global minor mode that will do this kind of tracking for you. All you need to do is switch it on using M-x rcirc-track-minor-mode. To make this permanent, add the following to your init file:
(rcirc-track-minor-mode 1)
When other people say things in buffers that are currently buried (no window is showing them), the mode line will now show you the abbreviated channel or nick name. Use C-c C-SPC to switch to these buffers.
By default the channel names are abbreviated, set
rcirc-track-abbrevate-flag to a non-nil value. This might be
interesting if the IRC activities are not tracked in the mode line,
but somewhere else.
If you prefer not to load rcirc immediately, you can delay the
activation of this mode:
(add-hook 'rcirc-mode-hook
(lambda ()
(rcirc-track-minor-mode 1)))
If you’ve joined a very active support channel, tracking activity is no longer useful. The channel will be always active. Switching to active channels using C-c C-SPC no longer works as expected.
The solution is to mark this channel as a low priority channel. Use C-c C-l to make the current channel a low-priority channel. Low priority channels have the modeline indicator “LowPri”. C-c C-SPC will not switch to low priority channels unless you use the C-u prefix.
If you prefer a channel to never show up in the modeline, then you have to ignore it. Use C-c TAB to ignore the current channel.
3.2 People
The most important command available to the discerning IRC user is
/ignore. It’s the big equalizer online: If people aggravate
you, just ignore them.
This is of course a crude all-or-nothing solution. Fear not,
rcirc offers alternatives: You can “brighten” your buddies
and “dim” certain other nicks that you don’t want to ignore
altogether.
/ignore¶-
This command toggles the ignore status of a nick, if you provide one. If you don’t provide a nick, the command lists all the nicks you are ignoring. All messages by ignored nicks are—you guessed it—ignored. Since only “operators” can kick people from channels, the ignore command is often the only way to deal with some of the more obnoxious fellows online. Example:
/ignore rudybot. /bright¶-
This command toggles the bright status of a nick, if you provide one. If you don’t provide a nick, the command lists all the “brightened” nicks. All messages by brightened nicks are—you guessed it—brightened. Use this for your friends. Example:
/bright rcy. /dim¶-
This command toggles the dim status of a nick, if you provide one. If you don’t provide a nick, the command lists all the “dimmed” nicks. All messages by dimmed nicks are—you guessed it—dimmed. Use this for boring people and bots. If you are tracking channel activity, messages by dimmed nicks will not register as activity. Example:
/dim fsbot.
3.3 Keywords
On a busy channel, you might want to ignore all activity (using C-c TAB) and just watch for certain keywords. The following command allows you to highlight certain keywords:
/keyword¶This command toggles the highlighting of a keyword, if you provide one. If you don’t provide a keyword, the current keywords are listed. Example:
/keyword manual.
3.4 Notices
In busy channels you might not be interested in all the joining, parting, quitting, and renaming that goes on. You can omit those notices using C-c C-o.
You can control which notices get omitted via the
rcirc-omit-responses variable. Here’s an example of how to
omit away messages:
(setopt rcirc-omit-responses '("JOIN" "PART" "QUIT" "NICK" "AWAY"))
Notice that these messages will not be omitted if the nick in question
has recently been active. After all, you don’t want to continue a
conversation with somebody who just left. That’s why rcirc
checks recent lines in the buffer to figure out if a nick has been
active and only omits a message if the nick has not been active. The
window rcirc considers is controlled by the
rcirc-omit-threshold variable.
Certain messages can be omitted by default, unless the user manual
requests them. For example, if you don’t want to display TOPIC
and NAMES messages, after reconnecting, you can configure
rcirc-omit-unless-requested to hide:
(setopt rcirc-omit-unless-requested '("TOPIC" "NAMES"))
Now NAMES will only be displayed, after it has been requested via the
rcirc-cmd-name command.
4 Hacking and Tweaking
Here are some examples of stuff you can do to configure rcirc.
- Skipping
/awaymessages using handlers - Using fly spell mode
- Scrolling conservatively
- Changing the time stamp format
- Defining a new command
- Using rcirc with bouncers
- Dealing with Bridge Bots
4.1 Skipping /away messages using handlers
The IRC protocol specifies how certain events are signaled from server
to client. These events have numbers and are dealt with using so-called
handlers. You can override existing handlers by exploiting the naming
convention adopted for rcirc.
Here’s how to stop rcirc from printing /away messages.
Since rcirc doesn’t define a 301 handler, you don’t need to
require rcirc before defining the handler:
(defun rcirc-handler-301 (process cmd sender args) "/away message handler.")
4.2 Using fly spell mode
The following code activates Fly Spell Mode
for rcirc buffers:
(add-hook 'rcirc-mode-hook (lambda ()
(flyspell-mode 1)))
See Flyspell mode in The GNU Emacs Manual, for details.
4.3 Scrolling conservatively
IRC buffers are constantly growing. If you want to see as much as
possible at all times, you would want the prompt at the bottom of the
window when possible. The following snippet uses a local value for
scroll-conservatively to achieve this:
(add-hook 'rcirc-mode-hook
(lambda ()
(set (make-local-variable 'scroll-conservatively)
8192)))
See Scrolling conservatively in The GNU Emacs Manual, for details.
4.4 Changing the time stamp format
rcirc-time-format is the format used for the time stamp. Here’s
how to include the date in the time stamp:
(setopt rcirc-time-format "%Y-%m-%d %H:%M ")
If you don’t wish to use verbose time formatting all the time, you can
use the rcirc-when command to display a complete timestamp for
the message at point.
4.5 Defining a new command
Here’s a simple new command, /sv. With it, you can boast about
your IRC client. It shows how you can use rcirc-define-command to
define new commands.
We’re waiting for the definition of this command until rcirc is loaded
because rcirc-define-command is not yet available, and without
rcirc loaded, the command wouldn’t do us much good anyway.
(with-eval-after-load 'rcirc
(rcirc-define-command sv ()
"Boast about rcirc."
(interactive "i")
(rcirc-send-message process target "I use " rcirc-id-string)))
4.6 Using rcirc with bouncers
Some bouncers multiplex connections to various servers, but have to
modify nicks and channel names to make this work. The channel
#emacs on irc.libera.chat becomes
#emacs/irc.libera.chat.
The options rcirc-nick-filter and rcirc-channel-filter
can be used to make this feel more natural. When set to functions,
these will be used to change how nicks and channel names are
displayed. A simple configuration to fix the above example might be:
(defun my/rcirc-remove-suffix (STR)
"Remove suffixes from STR."
(save-match-data
(if (string-match "/[[:alpha:]]+?\\'" str)
(substring str 0 (match-beginning 0))
str)))
(setopt rcirc-nick-filter #'my/rcirc-remove-suffix
rcirc-channel-filter #'local/rcirc-soju-suffix)
4.7 Dealing with Bridge Bots
It is increasingly common for IRC channels to be “bridged” onto other networks such as XMPP, Matrix, etc. Sometimes the software does a good job at mapping each non-IRC user into an IRC user, but more often than not it doesn’t. In that case you might receive a message like:
09:47 <bridge> <john> I am not on IRC
where ‘bridge’ is a bot responsible for sending messages back and
forth between networks, and ‘john’ is the user name of someone on
a different network. Note that the bot indicates this within the
message (<john> I am not on IRC) that appears in your chat
buffer.
If this annoys you, the user option rcirc-bridge-bot-alist may
be of use. It consists of descriptions of what users are these kinds
of “bridge bots” and how they format their messages. To handle the
above example, we might set the user option to:
(setopt rcirc-bridge-bot-alist
'(("bridge" . "<\\(.+?\\)>[[:space:]]+")))
If there is an entry for the current user, rcirc will take the
associated regular expression and try to find a match in the message
string. If it manages to find anything, the matching expression is
deleted from the message. The regular expression must contain at
least one group that will match the user name of the bridged message.
This will then be used to replace the username of the bridge bot.
Appendix A GNU Free Documentation License
Copyright © 2000, 2001, 2002, 2007, 2008 Free Software Foundation, Inc. https://fsf.org/ Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed.
- PREAMBLE
The purpose of this License is to make a manual, textbook, or other functional and useful document free in the sense of freedom: to assure everyone the effective freedom to copy and redistribute it, with or without modifying it, either commercially or noncommercially. Secondarily, this License preserves for the author and publisher a way to get credit for their work, while not being considered responsible for modifications made by others.
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.
- APPLICABILITY AND DEFINITIONS
This License applies to any manual or other work, in any medium, that contains a notice placed by the copyright holder saying it can be distributed under the terms of this License. Such a notice grants a world-wide, royalty-free license, unlimited in duration, to use that work under the conditions stated herein. The “Document”, below, refers to any such manual or work. Any member of the public is a licensee, and is addressed as “you”. You accept the license if you copy, modify or distribute the work in a way requiring permission under copyright law.
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- VERBATIM COPYING
You may copy and distribute the Document in any medium, either commercially or noncommercially, provided that this License, the copyright notices, and the license notice saying this License applies to the Document are reproduced in all copies, and that you add no other conditions whatsoever to those of this License. You may not use technical measures to obstruct or control the reading or further copying of the copies you make or distribute. However, you may accept compensation in exchange for copies. If you distribute a large enough number of copies you must also follow the conditions in section 3.
You may also lend copies, under the same conditions stated above, and you may publicly display copies.
- COPYING IN QUANTITY
If you publish printed copies (or copies in media that commonly have printed covers) of the Document, numbering more than 100, and the Document’s license notice requires Cover Texts, you must enclose the copies in covers that carry, clearly and legibly, all these Cover Texts: Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover. Both covers must also clearly and legibly identify you as the publisher of these copies. The front cover must present the full title with all words of the title equally prominent and visible. You may add other material on the covers in addition. Copying with changes limited to the covers, as long as they preserve the title of the Document and satisfy these conditions, can be treated as verbatim copying in other respects.
If the required texts for either cover are too voluminous to fit legibly, you should put the first ones listed (as many as fit reasonably) on the actual cover, and continue the rest onto adjacent pages.
If you publish or distribute Opaque copies of the Document numbering more than 100, you must either include a machine-readable Transparent copy along with each Opaque copy, or state in or with each Opaque copy a computer-network location from which the general network-using public has access to download using public-standard network protocols a complete Transparent copy of the Document, free of added material. If you use the latter option, you must take reasonably prudent steps, when you begin distribution of Opaque copies in quantity, to ensure that this Transparent copy will remain thus accessible at the stated location until at least one year after the last time you distribute an Opaque copy (directly or through your agents or retailers) of that edition to the public.
It is requested, but not required, that you contact the authors of the Document well before redistributing any large number of copies, to give them a chance to provide you with an updated version of the Document.
- MODIFICATIONS
You may copy and distribute a Modified Version of the Document under the conditions of sections 2 and 3 above, provided that you release the Modified Version under precisely this License, with the Modified Version filling the role of the Document, thus licensing distribution and modification of the Modified Version to whoever possesses a copy of it. In addition, you must do these things in the Modified Version:
- Use in the Title Page (and on the covers, if any) a title distinct from that of the Document, and from those of previous versions (which should, if there were any, be listed in the History section of the Document). You may use the same title as a previous version if the original publisher of that version gives permission.
- List on the Title Page, as authors, one or more persons or entities responsible for authorship of the modifications in the Modified Version, together with at least five of the principal authors of the Document (all of its principal authors, if it has fewer than five), unless they release you from this requirement.
- State on the Title page the name of the publisher of the Modified Version, as the publisher.
- Preserve all the copyright notices of the Document.
- Add an appropriate copyright notice for your modifications adjacent to the other copyright notices.
- Include, immediately after the copyright notices, a license notice giving the public permission to use the Modified Version under the terms of this License, in the form shown in the Addendum below.
- Preserve in that license notice the full lists of Invariant Sections and required Cover Texts given in the Document’s license notice.
- Include an unaltered copy of this License.
- Preserve the section Entitled “History”, Preserve 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.
- 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.
- For any section Entitled “Acknowledgements” or “Dedications”, Preserve the Title of the section, and preserve in the section all the substance and tone of each of the contributor acknowledgements and/or dedications given therein.
- 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.
- Delete any section Entitled “Endorsements”. Such a section may not be included in the Modified Version.
- Do not retitle any existing section to be Entitled “Endorsements” or to conflict in title with any Invariant Section.
- Preserve any Warranty Disclaimers.
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.
- COMBINING DOCUMENTS
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, and that you preserve all their Warranty Disclaimers.
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.”
- COLLECTIONS OF DOCUMENTS
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.
- AGGREGATION WITH INDEPENDENT WORKS
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, is called an “aggregate” if the copyright resulting from the compilation is not used to limit the legal rights of the compilation’s users beyond what the individual works permit. When the Document is included in an aggregate, this License does not apply to the other works in the aggregate which 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 half of the entire aggregate, the Document’s Cover Texts may be placed on covers that bracket the Document within the aggregate, or the electronic equivalent of covers if the Document is in electronic form. Otherwise they must appear on printed covers that bracket the whole aggregate.
- TRANSLATION
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, and all the license notices in the Document, and any Warranty Disclaimers, provided that you also include the original English version of this License and the original versions of those notices and disclaimers. In case of a disagreement between the translation and the original version of this License or a notice or disclaimer, the original version will prevail.
If a section in the Document is Entitled “Acknowledgements”, “Dedications”, or “History”, the requirement (section 4) to Preserve its Title (section 1) will typically require changing the actual title.
- TERMINATION
You may not copy, modify, sublicense, or distribute the Document except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense, or distribute it is void, and will automatically terminate your rights under this License.
However, if you cease all violation of this License, then your license from a particular copyright holder is reinstated (a) provisionally, unless and until the copyright holder explicitly and finally terminates your license, and (b) permanently, if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation.
Moreover, your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means, this is the first time you have received notice of violation of this License (for any work) from that copyright holder, and you cure the violation prior to 30 days after your receipt of the notice.
Termination of your rights under this section does not terminate the licenses of parties who have received copies or rights from you under this License. If your rights have been terminated and not permanently reinstated, receipt of a copy of some or all of the same material does not give you any rights to use it.
- FUTURE REVISIONS OF THIS LICENSE
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 https://www.gnu.org/licenses/.
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. If the Document specifies that a proxy can decide which future versions of this License can be used, that proxy’s public statement of acceptance of a version permanently authorizes you to choose that version for the Document.
- RELICENSING
“Massive Multiauthor Collaboration Site” (or “MMC Site”) means any World Wide Web server that publishes copyrightable works and also provides prominent facilities for anybody to edit those works. A public wiki that anybody can edit is an example of such a server. A “Massive Multiauthor Collaboration” (or “MMC”) contained in the site means any set of copyrightable works thus published on the MMC site.
“CC-BY-SA” means the Creative Commons Attribution-Share Alike 3.0 license published by Creative Commons Corporation, a not-for-profit corporation with a principal place of business in San Francisco, California, as well as future copyleft versions of that license published by that same organization.
“Incorporate” means to publish or republish a Document, in whole or in part, as part of another Document.
An MMC is “eligible for relicensing” if it is licensed under this License, and if all works that were first published under this License somewhere other than this MMC, and subsequently incorporated in whole or in part into the MMC, (1) had no cover texts or invariant sections, and (2) were thus incorporated prior to November 1, 2008.
The operator of an MMC Site may republish an MMC contained in the site under CC-BY-SA on the same site at any time before August 1, 2009, provided the MMC is eligible for relicensing.
ADDENDUM: 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 1.3 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 the section entitled ``GNU Free Documentation License''.
If you have Invariant Sections, Front-Cover Texts and Back-Cover Texts, replace the “with…Texts.” line with this:
with the Invariant Sections being list their titles, with
the Front-Cover Texts being list, and with the Back-Cover Texts
being list.
If you have Invariant Sections without Cover Texts, or some other combination of the three, merge those two alternatives to suit the situation.
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.
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