Initial Commit

[packages] / xemacs-packages / os-utils / os-utils.texi

@c -*-texinfo-*-
@c
@c Copyright (C) 2002, 2003 Free Software Foundation, Inc.
@c Copyright (C) 2003 Jake Colman
@c
@c @setfilename os-utils.info
@settitle Operating System Utilities for XEmacs
@ifinfo
@dircategory XEmacs Editor
@direntry
* OS Utilities: (os-utils).     Operating System Utilities for XEmacs.
@end direntry
@end ifinfo

@copying
This manual is part of XEmacs.

XEmacs is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

XEmacs is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License
along with XEmacs; see the file COPYING.  If not, write to the Free
Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.
@end copying

@node Top, Copying, (dir), (dir)
@chapter The Operating System Utilities Package

@ifinfo
This Info file contains the manual for the Operating System Utilities package.
@end ifinfo

The node name for each entry in the menu is the name of the elisp file
containing the code that implements the functionality described.  It is
highly recommended that you briefly peruse the elisp source code since it can
provide valuable information on usage and technique.  This can easily be done
by typing @code{C-x 4 l <filename> RET} where <filename> is the name of the
elisp file to be loaded.

@menu
* Copying::                     Why this manual is GPL, and what that means

Archive Management
* tar-mode::                    Simple Editing of TAR Files
* arc-mode::                    Simple Editing of Archives

Compression/Decompression
* crypt::                       Handling for Compressed and Encrypted Files
* jka-compr::                   Reading/Writing/Loading Compressed Files
* uncompress::                  Auto-Decompression Hook for Visiting .Z Files

Communications
* telnet::                      Execute a Telnet Session From Within an Emacs Buffer
* ssh::                         Remote Login Interface Using SSH
* ftelnet::                     Remote Login Interface Using Telnet
* rlogin::                      Remote Login Interface Using rlogin
* mchat::                       Multicast Chatting
* kermit::                      Using Shell Mode With Kermit
* terminal::                    Terminal Emulator

Miscellaneous
* spell::                       Spelling Correction
* background::                  Fun With Background Jobs
* inf-lisp::                    Inferior-Lisp Mode
* ledit::                       ledit

Appendices:
* XEmacs License::              The GNU General Public License
@end menu

@node Copying, tar-mode, Top, Top
@chapter Copying

This document may be redistributed, verbatim or in modified form, under
the terms of the GNU General Public License, version 2 or any later
version.  The same terms apply to the libraries it documents.  A copy
of the General Public License is provided as an Appendix.

Most XEmacs documentation has its own license, which is an ancestor of
the GNU Free Documentation License (@dfn{FDL}), and whose terms are
quite similar to those imposed by GNU on Emacs documentation.  Why is
this manual licensed differently (under the GNU General Public License,
or @dfn{GPL}), and why does it have to be distributed separately from
the XEmacs User's Guide and the XEmacs Lisp Reference Manual?

Taking the second question first, XEmacs is @dfn{community-owned}
software.  That is, unlike GNU Emacs, there is no monopoly copyright
holder.  Many of us, including the original Lucid authors, have
contributed our copyrights to the Free Software Foundation (FSF), and of
course much content is derived from GNU Emacs, and therefore is held by
the FSF.  Another large chunk is held by Sun Microsystems, and a few
individual authors hold copyright to thousands of lines each.  But many
individuals hold copyright to only a few dozen lines.  Like the Linux
kernel, copyright ownership is distributed throughout a community.

However, its license is ``copyleft,'' @emph{i.e.}, it @emph{requires}
that you redistribute it under terms @emph{identical} to those under
which you received it, unless you have explicit permission of the
copyright holder.  Because of the multiple owners, determining the
ownership of any given part of XEmacs is tedious, and perhaps
impossible.  For practical purposes, then, the license of any
substantial chunk of existing XEmacs content cannot be changed, except
to a later version of the GPL, for those parts under GPL.  (That is due
to the @emph{explicit} permission to change to a later version of the
GPL, present in every file of XEmacs.)

Unfortunately, this severe restriction means that the GPL, FDL, and the
XEmacs documentation license (@dfn{XDL}) are @emph{mutually
incompatible}.  That is, content licensed under any of the GPL, FDL, or
XDL @emph{may not} be mixed with content licensed under either of the
other two without changing the license of some of the content.  But this
requires permission of the copyright holder, which is often difficult or
impossible to get.

For example, you @emph{may not} take comments or docstrings from XEmacs
code and add them to the Lispref to mend a gap in the latter's coverage.
You @emph{may not} copy text from the Lispref into docstrings in the
code.  And you @emph{may not} copy text from the GNU Emacs Lisp
Reference to the XEmacs Lisp Reference Manual.  (In this case it is at
least trivial to ask permission, although it is rather unclear whether
it would be granted.)

In fact, parts of this document were derived by copying from XEmacs code
under the GPL, without any further permission from the authors.  Thus,
this document must be distributed under the GPL, as a ``volume''
separate from the XEmacs documentation under the XDL.  Note that the
``mere aggregation'' clauses allow us to distribute in the same
tarball.  But incorporating it as a node in the Lispref is prohibited,
even if done by inclusion.

A bit of advocacy:

If you look carefully at the additional restrictions imposed by the
soi-disant "free" documentation licenses, you discover that they are
simply proprietary restrictions guaranteeing a certain amount of
@emph{unpaid} political advertising to the Free Software Foundation and
GNU Project (and in the case of the FDL, this is extended to commercial
advertising by authors of original or derived works).  Whether this is
``ethically justified'' or not is a difficult question.  What is certain
is that there is little social benefit to these terms (since the license
documents themselves contain the advocacy and must be included with any
distribution).

I conclude it makes sense for XEmacs to reduce its restrictions, where
possible, to the ``least common denominator,'' the GNU General Public
License.

@node tar-mode, arc-mode, Copying, Top
@chapter Simple Editing of TAR Files

This package attempts to make dealing with Unix 'tar' archives easier.  When
this code is loaded, visiting a file whose name ends in '.tar' will cause the
contents of that archive file to be displayed in a Dired-like listing.  It is
then possible to use the customary Dired keybindings to extract sub-files
from that archive, either by reading them into their own editor buffers, or
by copying them directly to arbitrary files on disk.  It is also possible to
delete sub-files from within the tar file and write the modified archive back
to disk, or to edit sub-files within the archive and re-insert the modified
files into the archive.  See the documentation string of @code{tar-mode} for
more info.

To configure this package, type:

@example
  M-x customize-group RET tar RET
@end example

@node arc-mode, crypt, tar-mode, Top
@chapter Simple Editing of Archives

This library not documented.  Please contribute!

To configure this package, type:

@example
  M-x customize-group RET archive RET
@end example

@node crypt, jka-compr, arc-mode, Top
@chapter Handling for Compressed and Encrypted Files

The basic purpose of this package of Lisp functions is to recognize
automatically encrypted and encoded (i.e., compressed) files when they are
first visited or written.  The BUFFER corresponding to the file is decoded
and/or decrypted before it is presented to the user.  The file itself is
unchanged on the disk.  When the buffer is subsequently saved to disk, a hook
function re-encodes the buffer before the actual disk write takes place.

This package recognizes all sorts of compressed files by a magic number at
the beginning of these files but uses a heuristic to detect encrypted files.
If you are asked for an encryption key for a file that is in fact not
encrypted, just hit RET and the file will be accepted as is, and the crypt
minor mode will not be entered.

Other types of encoding programs may be added to this package by using the
variable @code{crypt-encoding-alist} which contains a table of encoding
programs such as @code{compress}, @code{gzip} (GNU zip), @code{freeze}, and
@code{compact}.

This new extended version of crypt now monitors the filename extensions of
buffers that are written out using @code{write-file} (@kbd{C-x C-w}).  If the
filename extension matches one of the extensions listed in
@code{crypt-encoding-alist}, then this package will write the file out using
the corresponding encoding (compression) method. This is done whether or not
the buffer originated from a previously encoded (compressed) file.

Thus, if the user is editing a file that may or may not have been encoded
originally (e.g., @file{foobar.Z} or @file{foobar}) and decides to write it
to a different file (e.g., @file{barfoo} or @file{barfoo.z} or
@file{barfoo.C}).  This package will examine the filename extension and write
the buffer in plain format or an alternate encoding (compression) format by
searching through the entries in the table of encoding methods
@code{crypt-encoding-alist}.  This change in encoding state is done
automatically if the variable @code{crypt-auto-write-buffer} is t otherwise
the user is asked.

To use this package, put the line @code{(require 'crypt)} in your
initialization file.  Do not bother trying to autoload this file; this
package uses @code{find-file} and @code{write-file} hooks and thus should be
loaded the first time you visit any sort of file.  Any package loaded after
this one that appends something to @code{write-file-hooks} will not be
executed because this package writes out the file.  Other packages that
append to @code{write-file-hooks} should either be modified to prepend to
that hook or be loaded before this one (preferably the former).

NOTE: encryption users should set @code{crypt-encryption-type} to one of the
values in @code{crypt-encryption-alist}.

To configure this package, type:

@example
  M-x customize-group RET compression RET
@end example

@node jka-compr, uncompress, crypt, Top
@chapter Reading/Writing/Loading Compressed Files

This package implements low-level support for reading, writing, and loading
compressed files.  It hooks into the low-level file I/O functions (including
@code{write-region} and @code{insert-file-contents}) so that they
automatically compress or uncompress a file if the file appears to need it
(based on the extension of the file name).  Packages like Rmail, VM, GNUS,
and Info should be able to work with compressed files without modification.

The operation of this package should be transparent to the user (except for
messages appearing when a file is being compressed or uncompressed).

The variable, @code{jka-compr-compression-info-list} can be used to customize
@code{jka-compr} to work with other compression programs.  The default value
of this variable allows @code{jka-compr} to work with Unix compress and gzip.

To activate this package, add the following to your initialization file:

@example
  (toggle-auto-compression 1 t)  ; enable compression/decompression
@end example

To configure this package, type:

@example
  M-x customize-group RET jka-compr RET
@end example

@node uncompress, telnet, jka-compr, Top
@chapter Auto-Decompression Hook for Visiting .Z Files

This package can be used to arrange for automatic uncompress of compressed
files when they are visited.  All that's necessary is to load it.  This can
conveniently be done from your initialization file.

@code{M-x auto-compression-mode} is a more modern replacement for this
package.

@node telnet, ssh, uncompress, Top
@chapter Execute a Telnet Session From Within an Emacs Buffer

This mode is intended to be used for telnet or rsh to a remote host;
@code{telnet} and @code{rsh} are the two entry points.  Multiple telnet or
rsh sessions are supported.

Normally, input is sent to the remote telnet/rsh line-by-line, as you type
@kbd{RET} or @kbd{LFD}.  @kbd{C-c C-c} sends a @kbd{C-c} to the remote
immediately; @kbd{C-c C-z} sends @kbd{C-z} immediately.  @kbd{C-c C-q}
followed by any character sends that character immediately.

All @kbd{RET} characters are filtered out of the output coming back from the
remote system.  The mode tries to do other useful translations based on what
it sees coming back from the other system before the password query.  It
knows about UNIX, ITS, TOPS-20 and Explorer systems.

You can use the global @code{telnet-host-properties} to associate a telnet
program and login name with each host you regularly telnet to.

To configure this package, type:

@example
  M-x customize-group RET telnet RET
@end example

@node ssh, ftelnet, telnet, Top
@chapter Remote Login Interface Using SSH

This package provides support for remote logins using @code{ssh}.  The
package is layered on top of shell.el; the code here only accounts for the
variations needed to handle a remote process, e.g. directory tracking and the
sending of some special characters.

If you wish for ssh mode to prompt you in the minibuffer for passwords when a
password prompt appears, just enter @code{M-x send-invisible} and type in
your line, or add @code{comint-watch-for-password-prompt} to
@code{comint-output-filter-functions}.

To configure this package, type:

@example
  M-x customize-group RET ssh RET
@end example

@node ftelnet, rlogin, ssh, Top
@chapter Remote Login Interface Using Telnet

This package provides support for remote logins using @code{telnet}.  The
package is layered on top of shell.el; the code here only accounts for the
variations needed to handle a remote process, e.g. directory tracking and the
sending of some special characters.

If you wish for ftelnet mode to prompt you in the minibuffer for passwords
when a password prompt appears, just enter @kbd{M-x send-invisible} and type
in your line, or add @code{comint-watch-for-password-prompt} to
@code{comint-output-filter-functions}.

@node rlogin, mchat, ftelnet, Top
@chapter Remote Login Interface Using rlogin

This package provides support for remote logins using @code{rlogin}.  The
package is layered on top of shell.el; the code here only accounts for the
variations needed to handle a remote process, e.g. directory tracking and the
sending of some special characters.

If you wish for rlogin mode to prompt you in the minibuffer for passwords
when a password prompt appears, just enter @kbd{M-x send-invisible} and type
in your line, or add @code{comint-watch-for-password-prompt} to
@code{comint-output-filter-functions}.

To configure this package, type:

@example
  M-x customize-group RET rlogin RET
@end example

@node mchat, kermit, rlogin, Top
@chapter Multicast Chatting

MChat is a package allowing a conversation to take place between a
potentially infinite number of people across the Internet. It uses the
Multicast support that has been added to XEmacs in the early 21.0 days. At
that time a rudimentary version of MChat was written, merely to illustrate
the feature, and almost nobody knew it, apart from the other
developers. This version is much improved and completely backwards
incompatible ;-).

NOTE: before using this package, you most likely have to customize the
@code{mchat-nsl-method} first. It specifies a program like @code{nsl} or
@code{nslookup} in order to retrieve the IP number of your machine.

The main entry point to the package is the @code{mchat} function which allows
you to open a multicast group based on the MChat protocol. There are a number
a variables that can be customized and their doc-string should be
self-explanatory. You might also want to look at the bindings (@kbd{C-h b})
in MChat buffers, or at the menubar entries to get an idea of what you can
do.

WARNING: the current version (but there's also a limitation in the internals
of XEmacs's processes) doesn't let you send messages longer than 500 octets
or so, including the protocol header. I plan to change this in the future
(see the todo list).

To configure this package, type:

@example
  M-x customize-group RET mchat RET
@end example

@node kermit, terminal, mchat, Top
@chapter Using Shell Mode With Kermit

This library not documented.  Please contribute!

@node terminal, spell, kermit, Top
@chapter Terminal Emulator

This library not documented.  Please contribute!

@node spell, background, terminal, Top
@chapter Spelling Correction

This mode provides an Emacs interface to the UNIX spell(1) program.  Entry
points are @code{spell-buffer}, @code{spell-word}, @code{spell-region} and
@code{spell-string}.  These facilities are documented in the Emacs user's
manual.

@node background, inf-lisp, spell, Top
@chapter Fun With Background Jobs

This library not documented.  Please contribute!

To configure this package, type:

@example
  M-x customize-group RET background RET
@end example

@node inf-lisp, ledit, background, Top
@chapter Inferior-Lisp Mode

This library not documented.  Please contribute!

@node ledit, XEmacs License, inf-lisp, Top
@chapter ledit

This library not documented.  Please contribute!

@node XEmacs License,  , ledit, Top
@chapter XEmacs License
@unnumbered GNU GENERAL PUBLIC LICENSE
@center Version 2, June 1991

@display
Copyright @copyright{} 1989, 1991 Free Software Foundation, Inc.
675 Mass Ave, Cambridge, MA 02139, USA

Everyone is permitted to copy and distribute verbatim copies
of this license document, but changing it is not allowed.
@end display

@unnumberedsec Preamble

  The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software---to make sure the software is free for all its users.  This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it.  (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.)  You can apply it to
your programs, too.

  When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.

  To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.

  For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
rights.

  We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.

  Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software.  If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.

  Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.

  The precise terms and conditions for copying, distribution and
modification follow.

@iftex
@unnumberedsec TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
@end iftex
@ifnottex
@center TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION
@end ifnottex

@enumerate 0
@item
This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License.  The ``Program'', below,
refers to any such program or work, and a ``work based on the Program''
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language.  (Hereinafter, translation is included without limitation in
the term ``modification''.)  Each licensee is addressed as ``you''.

Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope.  The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.

@item
You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.

You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.

@item
You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:

@enumerate a
@item
You must cause the modified files to carry prominent notices
stating that you changed the files and the date of any change.

@item
You must cause any work that you distribute or publish, that in
whole or in part contains or is derived from the Program or any
part thereof, to be licensed as a whole at no charge to all third
parties under the terms of this License.

@item
If the modified program normally reads commands interactively
when run, you must cause it, when started running for such
interactive use in the most ordinary way, to print or display an
announcement including an appropriate copyright notice and a
notice that there is no warranty (or else, saying that you provide
a warranty) and that users may redistribute the program under
these conditions, and telling the user how to view a copy of this
License.  (Exception: if the Program itself is interactive but
does not normally print such an announcement, your work based on
the Program is not required to print an announcement.)
@end enumerate

These requirements apply to the modified work as a whole.  If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works.  But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.

Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.

In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.

@item
You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:

@enumerate a
@item
Accompany it with the complete corresponding machine-readable
source code, which must be distributed under the terms of Sections
1 and 2 above on a medium customarily used for software interchange; or,

@item
Accompany it with a written offer, valid for at least three
years, to give any third party, for a charge no more than your
cost of physically performing source distribution, a complete
machine-readable copy of the corresponding source code, to be
distributed under the terms of Sections 1 and 2 above on a medium
customarily used for software interchange; or,

@item
Accompany it with the information you received as to the offer
to distribute corresponding source code.  (This alternative is
allowed only for noncommercial distribution and only if you
received the program in object code or executable form with such
an offer, in accord with Subsection b above.)
@end enumerate

The source code for a work means the preferred form of the work for
making modifications to it.  For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable.  However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.

If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.

@item
You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense or distribute the Program 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.

@item
You are not required to accept this License, since you have not
signed it.  However, nothing else grants you permission to modify or
distribute the Program or its derivative works.  These actions are
prohibited by law if you do not accept this License.  Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.

@item
Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions.  You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.

@item
If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License.  If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all.  For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.

If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.

It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices.  Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.

This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.

@item
If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded.  In such case, this License incorporates
the limitation as if written in the body of this License.

@item
The Free Software Foundation may publish revised and/or new versions
of the General Public 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.

Each version is given a distinguishing version number.  If the Program
specifies a version number of this License which applies to it and ``any
later version'', you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation.  If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
Foundation.

@item
If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission.  For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this.  Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.

@iftex
@heading NO WARRANTY
@end iftex
@ifnottex
@center NO WARRANTY
@end ifnottex

@item
BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW@.  EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM ``AS IS'' WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE@.  THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU@.  SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.

@item
IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.
@end enumerate

@iftex
@heading END OF TERMS AND CONDITIONS
@end iftex
@ifnottex
@center END OF TERMS AND CONDITIONS
@end ifnottex

@page
@unnumberedsec How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the ``copyright'' line and a pointer to where the full notice is found.

@smallexample
@var{one line to give the program's name and an idea of what it does.}
Copyright (C) 19@var{yy}  @var{name of author}

This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE@.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
@end smallexample

Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:

@smallexample
Gnomovision version 69, Copyright (C) 19@var{yy} @var{name of author}
Gnomovision comes with ABSOLUTELY NO WARRANTY; for details
type `show w'.  This is free software, and you are welcome
to redistribute it under certain conditions; type `show c'
for details.
@end smallexample

The hypothetical commands @samp{show w} and @samp{show c} should show
the appropriate parts of the General Public License.  Of course, the
commands you use may be called something other than @samp{show w} and
@samp{show c}; they could even be mouse-clicks or menu items---whatever
suits your program.

You should also get your employer (if you work as a programmer) or your
school, if any, to sign a ``copyright disclaimer'' for the program, if
necessary.  Here is a sample; alter the names:

@smallexample
@group
Yoyodyne, Inc., hereby disclaims all copyright
interest in the program `Gnomovision'
(which makes passes at compilers) written
by James Hacker.

@var{signature of Ty Coon}, 1 April 1989
Ty Coon, President of Vice
@end group
@end smallexample

This General Public License does not permit incorporating your program into
proprietary programs.  If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library.  If this is what you want to do, use the GNU Library General
Public License instead of this License.