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\input texinfo   @c -*- coding: latin-1; mode: texinfo; -*-
@c %**start of header
@setfilename ../info/efaq
@settitle GNU Emacs FAQ
@c %**end of header

@setchapternewpage odd

@c This is used in many places
@set VER 21.3

@copying
Copyright 2001, 2002, 2003 Free Software Foundation, Inc.
Copyright 1994,1995,1996,1997,1998,1999,2000 Reuven M. Lerner@*
Copyright 1992,1993 Steven Byrnes@*
Copyright 1990,1991,1992 Joseph Brian Wells@*

@quotation
This list of frequently asked questions about GNU Emacs with answers
("FAQ") may be translated into other languages, transformed into other
formats (e.g. Texinfo, Info, WWW, WAIS), and updated with new information.

The same conditions apply to any derivative of the FAQ as apply to the FAQ
itself.  Every copy of the FAQ must include this notice or an approved
translation, information on who is currently maintaining the FAQ and how to
contact them (including their e-mail address), and information on where the
latest version of the FAQ is archived (including FTP information).

The FAQ may be copied and redistributed under these conditions, except that
the FAQ may not be embedded in a larger literary work unless that work
itself allows free copying and redistribution.

[This version has been somewhat edited from the last-posted version
(as of August 1999) for inclusion in the Emacs distribution.]
@end quotation
@end copying

@dircategory Emacs
@direntry
* Emacs FAQ: (efaq).	Frequently Asked Questions about Emacs.
@end direntry

@c The @titlepage stuff only appears in the printed version
@titlepage
@sp 10
@center @titlefont{GNU Emacs FAQ}

@c The following two commands start the copyright page.
@page
@vskip 0pt plus 1filll
@insertcopying
@end titlepage

@node    Top, FAQ notation, (dir), (dir)

This is the GNU Emacs FAQ, last updated on @today{}.

The FAQ is maintained as a Texinfo document, allowing us to create HTML,
Info, and TeX documents from a single source file, and is slowly but
surely being improved.  Please bear with us as we improve on this
format.  This FAQ is maintained as a part of GNU Emacs.  If you find
any errors, or have any suggestions, please use @kbd{M-x report-emacs-bug}
to report them.

@menu
* FAQ notation::
* General questions::
* Getting help::
* Status of Emacs::
* Common requests::
* Bugs and problems::
* Compiling and installing Emacs::
* Finding Emacs and related packages::
* Major packages and programs::
* Key bindings::
* Alternate character sets::
* Mail and news::
* Concept index::
@end menu

@c ------------------------------------------------------------
@node FAQ notation, General questions, Top, Top
@chapter FAQ notation
@cindex FAQ notation

This chapter describes notation used in the GNU Emacs FAQ, as well as in
the Emacs documentation.  Consult this section if this is the first time
you are reading the FAQ, or if you are confused by notation or terms
used in the FAQ.

@menu
* Basic keys::
* Extended commands::
* On-line manual::
* File-name conventions::
* Common acronyms::
@end menu

@node Basic keys, Extended commands, FAQ notation, FAQ notation
@section What do these mean: @kbd{C-h}, @kbd{C-M-a}, @key{RET}, @kbd{@key{ESC} a}, etc.?
@cindex Basic keys
@cindex Control key, notation for
@cindex @key{Meta} key, notation for
@cindex Control-Meta characters, notation for
@cindex @kbd{C-h}, definition of
@cindex @kbd{C-M-h}, definition of
@cindex @key{DEL}, definition of
@cindex @key{ESC}, definition of
@cindex @key{LFD}, definition of
@cindex @key{RET}, definition of
@cindex @key{SPC}, definition of
@cindex @key{TAB}, definition of
@cindex Notation for keys

@itemize @bullet

@item
@kbd{C-x}: press the @key{x} key while holding down the @key{Control} key

@item
@kbd{M-x}: press the @key{x} key while holding down the @key{Meta} key
(if your computer doesn't have a @key{Meta} key, @pxref{No Meta key})

@item
@kbd{M-C-x}: press the @key{x} key while holding down both @key{Control}
and @key{Meta}

@item
@kbd{C-M-x}: a synonym for the above

@item
@key{LFD}: Linefeed or Newline; same as @kbd{C-j}

@item
@key{RET}: @key{Return}, sometimes marked @key{Enter}; same as @kbd{C-m}

@item
@key{DEL}: @key{Delete}, usually @strong{not} the same as
@key{Backspace}; same as @kbd{C-?} (see @ref{Backspace invokes help}, if
deleting invokes Emacs help)

@item
@key{ESC}: Escape; same as @kbd{C-[}

@item
@key{TAB}: Tab; same as @kbd{C-i}

@item
@key{SPC}: Space bar

@end itemize

Key sequences longer than one key (and some single-key sequences) are
written inside quotes or on lines by themselves, like this:

@display
  @kbd{M-x frobnicate-while-foo RET}
@end display

@noindent
Any real spaces in such a key sequence should be ignored; only @key{SPC}
really means press the space key.

The ASCII code sent by @kbd{C-x} (except for @kbd{C-?}) is the value
that would be sent by pressing just @key{x} minus 96 (or 64 for
upper-case @key{X}) and will be from 0 to 31.  On Unix and GNU/Linux
terminals, the ASCII code sent by @kbd{M-x} is the sum of 128 and the
ASCII code that would be sent by pressing just @key{x}.  Essentially,
@key{Control} turns off bits 5 and 6 and @key{Meta} turns on bit
7@footnote{
DOS and Windows terminals don't set bit 7 when the @key{Meta} key is
pressed.}.

@kbd{C-?} (aka @key{DEL}) is ASCII code 127.  It is a misnomer to call
@kbd{C-?}  a ``control'' key, since 127 has both bits 5 and 6 turned ON.
Also, on very few keyboards does @kbd{C-?} generate ASCII code 127.

@inforef{Text Characters, Text Characters, emacs}, and @inforef{Keys,
Keys, emacs}, for more information.  (@xref{On-line manual}, for more
information about Info.)

@node Extended commands, On-line manual, Basic keys, FAQ notation
@section What does @file{M-x @var{command}} mean?
@cindex Extended commands
@cindex Commands, extended
@cindex M-x, meaning of

@kbd{M-x @var{command}} means type @kbd{M-x}, then type the name of the
command, then type @key{RET}.  (@xref{Basic keys}, if you're not sure
what @kbd{M-x} and @key{RET} mean.)

@kbd{M-x} (by default) invokes the command
@code{execute-extended-command}.  This command allows you to run any
Emacs command if you can remember the command's name.  If you can't
remember the command's name, you can type @key{TAB} and @key{SPC} for
completion, @key{?} for a list of possibilities, and @kbd{M-p} and
@kbd{M-n} (or up-arrow and down-arrow on terminals that have these
editing keys) to see previous commands entered.  An Emacs @dfn{command}
is an @dfn{interactive} Emacs function.

@cindex @key{Do} key
Your system administrator may have bound other key sequences to invoke
@code{execute-extended-command}.  A function key labeled @kbd{Do} is a
good candidate for this, on keyboards that have such a key.

If you need to run non-interactive Emacs functions, see @ref{Evaluating
Emacs Lisp code}.

@node On-line manual, File-name conventions, Extended commands, FAQ notation
@section How do I read topic XXX in the on-line manual?
@cindex On-line manual, reading topics in
@cindex Reading topics in the on-line manual
@cindex Finding topics in the on-line manual
@cindex Info, finding topics in

When we refer you to some @var{topic} in the on-line manual, you can
read this manual node inside Emacs (assuming nothing is broken) by
typing @kbd{C-h i m emacs @key{RET} m @var{topic} @key{RET}}.

This invokes Info, the GNU hypertext documentation browser.  If you don't
already know how to use Info, type @key{?} from within Info.

If we refer to @var{topic}:@var{subtopic}, type @kbd{C-h i m emacs
@key{RET} m @var{topic} @key{RET} m @var{subtopic} @key{RET}}.

If these commands don't work as expected, your system administrator may
not have installed the Info files, or may have installed them
improperly.  In this case you should complain.

@xref{Getting a printed manual}, if you would like a paper copy of the
Emacs manual.

@node File-name conventions, Common acronyms, On-line manual, FAQ notation
@section What are @file{etc/SERVICE}, @file{src/config.h}, and @file{lisp/default.el}?
@cindex File-name conventions
@cindex Conventions for file names
@cindex Directories and files that come with Emacs

These are files that come with Emacs.  The Emacs distribution is divided
into subdirectories; the important ones are @file{etc}, @file{lisp}, and
@file{src}.

If you use Emacs, but don't know where it is kept on your system, start
Emacs, then type @kbd{C-h v data-directory @key{RET}}.  The directory
name displayed by this will be the full pathname of the installed
@file{etc} directory.  (This full path is recorded in the Emacs variable
@code{data-directory}, and @kbd{C-h v} displays the value and the
documentation of a variable.)

The location of your Info directory (i.e., where on-line documentation
is stored) is kept in the variable @code{Info-default-directory-list}.  Use
@kbd{C-h v Info-default-directory-list @key{RET}} to see the value of
this variable, which will be a list of directory names.  The last
directory in that list is probably where most Info files are stored.  By
default, Info documentation is placed in @file{/usr/local/info}.

Some of these files are available individually via FTP or e-mail; see
@ref{Informational files for Emacs}.  They all are available in the
source distribution.  Many of the files in the @file{etc} directory are
also available via the Emacs @samp{Help} menu, or by typing @kbd{C-h ?}
(@kbd{M-x help-for-help}).

Your system administrator may have removed the @file{src} directory and
many files from the @file{etc} directory.

@node Common acronyms,  , File-name conventions, FAQ notation
@section What are FSF, LPF, OSF, GNU, RMS, FTP, and GPL?
@cindex FSF, definition of
@cindex LPF, definition of
@cindex OSF, definition of
@cindex GNU, definition of
@cindex RMS, definition of
@cindex Stallman, Richard, acronym for
@cindex Richard Stallman, acronym for
@cindex FTP, definition of
@cindex GPL, definition of
@cindex Acronyms, definitions for
@cindex Common acronyms, definitions for

@table @asis

@item FSF
Free Software Foundation

@item LPF
League for Programming Freedom

@item OSF
Open Software Foundation

@item GNU
GNU's Not Unix

@item RMS
Richard Matthew Stallman

@item FTP
File Transfer Protocol

@item GPL
GNU General Public License

@end table

Avoid confusing the FSF, the LPF, and the OSF.  The LPF opposes
look-and-feel copyrights and software patents.  The FSF aims to make
high quality free software available for everyone.  The OSF is a
consortium of computer vendors which develops commercial software for
Unix systems.

The word ``free'' in the title of the Free Software Foundation refers to
``freedom,'' not ``zero dollars.''  Anyone can charge any price for
GPL-covered software that they want to.  However, in practice, the
freedom enforced by the GPL leads to low prices, because you can always
get the software for less money from someone else, since everyone has
the right to resell or give away GPL-covered software.

@c ------------------------------------------------------------
@node    General questions, Getting help, FAQ notation, Top
@chapter General questions
@cindex General questions

This chapter contains general questions having to do with Emacs, the
Free Software Foundation, and related organizations.

@menu
* The LPF::
* Real meaning of copyleft::
* Guidelines for newsgroup postings::
* Newsgroup archives::
* Reporting bugs::
* Unsubscribing from Emacs lists::
* Contacting the FSF::
@end menu

@node The LPF, Real meaning of copyleft, General questions, General questions
@section What is the LPF?
@cindex LPF, description of
@cindex League for Programming Freedom
@cindex Software patents, opposition to
@cindex Patents for software, opposition to

The LPF opposes the expanding danger of software patents and
look-and-feel copyrights.  To get more information, feel free to contact
the LPF via e-mail or otherwise.  You may also contact
@email{jbw@@cs.bu.edu, Joe Wells}; he will be happy to talk to you
about the LPF.

You can find more information about the LPF in the file @file{etc/LPF}.
More papers describing the LPF's views are available on the Internet and
also from @uref{http://lpf.ai.mit.edu/, the LPF home page}.

@node Real meaning of copyleft, Guidelines for newsgroup postings, The LPF, General questions
@section What is the real legal meaning of the GNU copyleft?
@cindex Copyleft, real meaning of
@cindex GPL, real meaning of
@cindex General Public License, real meaning of
@cindex Discussion of the GPL

The real legal meaning of the GNU General Public License (copyleft) will
only be known if and when a judge rules on its validity and scope.
There has never been a copyright infringement case involving the GPL to
set any precedents.  Please take any discussion regarding this issue to
the newsgroup @uref{news:gnu.misc.discuss}, which was created to hold the
extensive flame wars on the subject.

RMS writes:

@quotation
The legal meaning of the GNU copyleft is less important than the spirit,
which is that Emacs is a free software project and that work pertaining
to Emacs should also be free software.  ``Free'' means that all users
have the freedom to study, share, change and improve Emacs.  To make
sure everyone has this freedom, pass along source code when you
distribute any version of Emacs or a related program, and give the
recipients the same freedom that you enjoyed.
@end quotation

@node Guidelines for newsgroup postings, Newsgroup archives, Real meaning of copyleft, General questions
@section  What are appropriate messages for @uref{news:gnu.emacs.help}, @uref{news:gnu.emacs.bug}, @uref{news:comp.emacs}, etc.?
@cindex Newsgroups, appropriate messages for
@cindex GNU newsgroups, appropriate messages for
@cindex Usenet groups, appropriate messages for
@cindex Mailing lists, appropriate messages for
@cindex Posting messages to newsgroups

@cindex GNU mailing lists
The file @file{etc/MAILINGLISTS} describes the purpose of each GNU
mailing list.  (@xref{Informational files for Emacs}, if you want a copy
of the file.)  For those lists which are gatewayed with newsgroups, it
lists both the newsgroup name and the mailing list address.

The newsgroup @uref{news:comp.emacs} is for discussion of Emacs programs
in general.  This includes Emacs along with various other
implementations, such as XEmacs, JOVE, MicroEmacs, Freemacs, MG,
Unipress, CCA, and Epsilon.

Many people post Emacs questions to @uref{news:comp.emacs} because they
don't receive any of the @code{gnu.*} newsgroups.  Arguments have been
made both for and against posting GNU-Emacs-specific material to
@uref{news:comp.emacs}.  You have to decide for yourself.

Messages advocating ``non-free'' software are considered unacceptable on
any of the @code{gnu.*} newsgroups except for @uref{news:gnu.misc.discuss},
which was created to hold the extensive flame-wars on the subject.
``Non-free'' software includes any software for which the end user can't
freely modify the source code and exchange enhancements.  Be careful to
remove the @code{gnu.*} groups from the @samp{Newsgroups:} line when
posting a followup that recommends such software.

@uref{news:gnu.emacs.bug} is a place where bug reports appear, but avoid
posting bug reports to this newsgroup directly (@pxref{Reporting bugs}).

@node Newsgroup archives, Reporting bugs, Guidelines for newsgroup postings, General questions
@section Where can I get old postings to @uref{news:gnu.emacs.help} and other GNU groups?
@cindex Archived postings from @code{gnu.emacs.help}
@cindex Usenet archives for GNU groups
@cindex Old Usenet postings for GNU groups

The FSF has maintained archives of all of the GNU mailing lists for many
years, although there may be some unintentional gaps in coverage.  The
archive is not particularly well organized or easy to retrieve
individual postings from, but pretty much everything is there.

The archive is at @uref{ftp://ftp-mailing-list-archives.gnu.org}.

The archive can be browsed over the web at 
@uref{http://mail.gnu.org/archive/html/, the GNU mail archive}.

Web-based Usenet search services, such as
@uref{http://groups.google.com, Google}, also archive the
@code{gnu.*} groups.

@node Reporting bugs, Unsubscribing from Emacs lists, Newsgroup archives, General questions
@section Where should I report bugs and other problems with Emacs?
@cindex Bug reporting
@cindex Good bug reports
@cindex How to submit a bug report
@cindex Reporting bugs

The correct way to report Emacs bugs is by e-mail to
@email{bug-gnu-emacs@@gnu.org}.  Anything sent here also appears in the
newsgroup @uref{news:gnu.emacs.bug}, but please use e-mail instead of
news to submit the bug report.  This ensures a reliable return address
so you can be contacted for further details.

Be sure to read the ``Bugs'' section of the Emacs manual before reporting
a bug to bug-gnu-emacs!  The manual describes in detail how to submit a
useful bug report.  (@xref{On-line manual}, if you don't know how to read the
manual.)

RMS says:

@quotation
Sending bug reports to @email{help-gnu-emacs@@gnu.org} (which has the
effect of posting on @uref{news:gnu.emacs.help}) is undesirable because
it takes the time of an unnecessarily large group of people, most of
whom are just users and have no idea how to fix these problem.
@email{bug-gnu-emacs@@gnu.org} reaches a much smaller group of people
who are more likely to know what to do and have expressed a wish to
receive more messages about Emacs than the others.
@end quotation

RMS says it is sometimes fine to post to @uref{news:gnu.emacs.help}:

@quotation
If you have reported a bug and you don't hear about a possible fix,
then after a suitable delay (such as a week) it is okay to post on
@code{gnu.emacs.help} asking if anyone can help you.
@end quotation

If you are unsure whether you have found a bug, consider the following
non-exhaustive list, courtesy of RMS:

@quotation
If Emacs crashes, that is a bug.  If Emacs gets compilation errors
while building, that is a bug.  If Emacs crashes while building, that
is a bug.  If Lisp code does not do what the documentation says it
does, that is a bug.
@end quotation

@node Unsubscribing from Emacs lists, Contacting the FSF, Reporting bugs, General questions
@section  How do I unsubscribe from this mailing list?
@cindex Unsubscribing from GNU mailing lists
@cindex Removing yourself from GNU mailing lists

If you are receiving a GNU mailing list named @var{list}, you might be
able to unsubscribe from it by sending a request to the address
@email{@var{list}-request@@gnu.org}.  However, this will not work if you are
not listed on the main mailing list, but instead receive the mail from a
distribution point.  In that case, you will have to track down at which
distribution point you are listed.  Inspecting the @samp{Received} headers
on the mail messages may help, along with liberal use of the @samp{EXPN} or
@samp{VRFY} sendmail commands through @samp{telnet @var{site-address}
smtp}.  Ask your postmaster for help, if you cannot figure out these
details.

@node Contacting the FSF,  , Unsubscribing from Emacs lists, General questions
@section  What is the current address of the FSF?
@cindex Snail mail address of the FSF
@cindex Postal address of the FSF
@cindex Contracting the FSF
@cindex Free Software Foundation, contacting

@table @asis

@item E-mail
gnu@@gnu.org

@item Telephone
+1-617-542-5942

@item Fax
+1-617-542-2652

@item World Wide Web
@uref{http://www.gnu.org/}

@item Postal address
Free Software Foundation@*
59 Temple Place - Suite 330@*
Boston, MA 02111-1307@*
USA@*

@end table

@cindex Ordering GNU software
For details on how to order items directly from the FSF, see the
@uref{http://www.gnu.org/order/order.html, GNU Web site}.

@c ------------------------------------------------------------
@node Getting help, Status of Emacs, General questions, Top
@chapter Getting help
@cindex Getting help

This chapter tells you how to get help with Emacs

@menu
* Basic editing::
* Learning how to do something::
* Getting a printed manual::
* Emacs Lisp documentation::
* Installing Texinfo documentation::
* Printing a Texinfo file::
* Viewing Info files outside of Emacs::
* Informational files for Emacs::
* Help installing Emacs::
* Obtaining the FAQ::
@end menu

@node Basic editing, Learning how to do something, Getting help, Getting help
@section I'm just starting Emacs; how do I do basic editing?
@cindex Basic editing with Emacs
@cindex Beginning editing
@cindex Tutorial, invoking the
@cindex Self-paced tutorial, invoking the
@cindex Help system, entering the

Type @kbd{C-h t} to invoke the self-paced tutorial.  Just typing @kbd{C-h}
enters the help system.

Your system administrator may have changed @kbd{C-h} to act like
@key{DEL} to deal with local keyboards.  You can use @kbd{M-x
help-for-help} instead to invoke help.  To discover what key (if any)
invokes help on your system, type @kbd{M-x where-is @key{RET}
help-for-help @key{RET}}.  This will print a comma-separated list of key
sequences in the echo area.  Ignore the last character in each key
sequence listed.  Each of the resulting key sequences invokes help.

Emacs help works best if it is invoked by a single key whose value
should be stored in the variable @code{help-char}.

There is also a WWW-based tutorial for Emacs 18, much of which is also
relevant for later versions of Emacs, available at

@uref{http://kufacts.cc.ukans.edu/cwis/writeups/misc/emacsguide.html}

@node Learning how to do something, Getting a printed manual, Basic editing, Getting help
@section How do I find out how to do something in Emacs?
@cindex Help for Emacs
@cindex Learning to do something in Emacs
@cindex Reference card for Emacs
@cindex Overview of help systems

There are several methods for finding out how to do things in Emacs.

@itemize @bullet

@cindex Reading the Emacs manual
@item
The complete text of the Emacs manual is available on-line via the Info
hypertext reader.  Type @kbd{C-h i} to invoke Info.  Typing @key{h}
immediately after entering Info will provide a short tutorial on how to
use it.

@cindex Lookup a subject in a manual
@cindex Index search in a manual
@item
To quickly locate the section of the manual which discusses a certain
issue, or describes a command or a variable, type @kbd{C-h i m emacs
@key{RET} i @var{topic} @key{RET}}, where @var{topic} is the name of the
topic, the command, or the variable which you are looking for.  If this
does not land you on the right place in the manual, press @kbd{,}
(comma) repeatedly until you find what you need.  (The @kbd{i} and
@kbd{,} keys invoke the index-searching functions, which look for the
@var{topic} you type in all the indices of the Emacs manual.)

@cindex Apropos
@item
You can list all of the commands whose names contain a certain word
(actually which match a regular expression) using @kbd{C-h a} (@kbd{M-x
command-apropos}).

@cindex Command description in the manual
@item
The command @kbd{C-h C-f} (@code{Info-goto-emacs-command-node}) prompts
for the name of a command, and then attempts to find the section in the
Emacs manual where that command is described.

@cindex Finding commands and variables
@item
You can list all of the functions and variables whose names contain a
certain word using @kbd{M-x apropos}.

@item
You can list all of the functions and variables whose documentation
matches a regular expression or a string, using @kbd{M-x
apropos-documentation}.

@item
You can order a hardcopy of the manual from the FSF.  @xref{Getting a
printed manual}.

@cindex Reference cards, in other languages
@item
You can get a printed reference card listing commands and keys to
invoke them.  You can order one from the FSF for $1 (or 10 for $5),
or you can print your own from the @file{etc/refcard.tex} or
@file{etc/refcard.ps} files in the Emacs distribution.  Beginning with
version 21.1, the Emacs distribution comes with translations of the
reference card into several languages; look for files named
@file{etc/@var{lang}-refcard.*}, where @var{lang} is a two-letter code
of the language.  For example, the German version of the reference card
is in the files @file{etc/de-refcard.tex} and @file{etc/de-refcard.ps}.

@item
There are many other commands in Emacs for getting help and
information.  To get a list of these commands, type @samp{?} after
@kbd{C-h}.

@end itemize

@node Getting a printed manual, Emacs Lisp documentation, Learning how to do something, Getting help
@section How do I get a printed copy of the Emacs manual?
@cindex Printed Emacs manual, obtaining
@cindex Manual, obtaining a printed or HTML copy of
@cindex Emacs manual, obtaining a printed or HTML copy of

You can order a printed copy of the Emacs manual from the FSF.  For
details see the @uref{http://www.gnu.org/order/order.html, GNU Web site}.

@c The number 620 below is version-dependent!
The full Texinfo source for the manual also comes in the @file{man}
directory of the Emacs distribution, if you're daring enough to try to
print out this 620-page manual yourself (@pxref{Printing a Texinfo
file}).

If you absolutely have to print your own copy, and you don't have @TeX{},
you can get a PostScript version from

@uref{http://www.gnu.org/manual/emacs/ps/emacs.ps.gz}

@cindex HTML version of Emacs manual, obtaining
An HTML version of the manual is at

@uref{www.gnu.org/manual/emacs/index.html}

@xref{Learning how to do something}, for how to view the manual on-line.

@node Emacs Lisp documentation, Installing Texinfo documentation, Getting a printed manual, Getting help
@section Where can I get documentation on Emacs Lisp?
@cindex Documentation on Emacs Lisp
@cindex Function documentation
@cindex Variable documentation
@cindex Emacs Lisp Reference Manual
@cindex Reference manual for Emacs Lisp

Within Emacs, you can type @kbd{C-h f} to get the documentation for a
function, @kbd{C-h v} for a variable.

For more information, obtain the Emacs Lisp Reference Manual.  Details
on ordering it from FSF are on the
@uref{http://www.gnu.org/order/order.html, GNU Web site}.

The Emacs Lisp Reference Manual is also available on-line, in Info
format.  Texinfo source for the manual (along with pregenerated Info
files) is available at

@uref{ftp://ftp.gnu.org/pub/gnu/emacs/elisp-manual-21-2.6.tar.gz}

and all mirrors of @samp{ftp.gnu.org} (for a list, @pxref{Current GNU
distributions}).  @xref{Installing Texinfo documentation}, if you want
to install the Info files, or @ref{Printing a Texinfo file}, if you want
to use the Texinfo source to print the manual yourself.

An HTML version of the Emacs Lisp Reference Manual is available at

@uref{http://www.gnu.org/manual/elisp-manual-21-2.6/elisp.html}

@node Installing Texinfo documentation, Printing a Texinfo file, Emacs Lisp documentation, Getting help
@section How do I install a piece of Texinfo documentation?
@cindex Texinfo documentation, installing
@cindex Installing Texinfo documentation
@cindex New Texinfo files, installing
@cindex Documentation, installing new Texinfo files
@cindex Info files, how to install

First, you must turn the Texinfo files into Info files.  You may do this
using the stand-alone @file{makeinfo} program, available as part of the latest
Texinfo package at

@uref{ftp://ftp.gnu.org/pub/gnu/texinfo/texinfo-4.0.tar.gz}

and all mirrors of @samp{ftp.gnu.org} (for a list, @pxref{Current GNU
distributions}).

For information about the Texinfo format, read the Texinfo manual which
comes with the Texinfo package.  This manual also comes installed in
Info format, so you can read it on-line; type @kbd{C-h i m texinfo
@key{RET}}.

Alternatively, you could use the Emacs command @kbd{M-x
texinfo-format-buffer}, after visiting the Texinfo source file of the
manual you want to convert.

Neither @code{texinfo-format-buffer} nor @file{makeinfo} installs the
resulting Info files in Emacs's Info tree.  To install Info files,
perform these steps:

@enumerate
@item
Move the files to the @file{info} directory in the installed Emacs
distribution.  @xref{File-name conventions}, if you don't know where that
is.

@item
Run the @code{install-info} command, which is part of the Texinfo
distribution, to update the main Info directory menu, like this:

@example
 install-info --info-dir=@var{dir-path} @var{dir-path}/@var{file}
@end example

@noindent
where @var{dir-path} is the full path to the directory where you copied
the produced Info file(s), and @var{file} is the name of the Info file
you produced and want to install.

If you don't have the @code{install-info} command installed, you can
edit the file @file{info/dir} in the installed Emacs distribution, and
add a line for the top level node in the Info package that you are
installing.  Follow the examples already in this file.  The format is:

@example
* Topic: (relative-pathname).  Short description of topic.
@end example

@end enumerate

If you want to install Info files and you don't have the necessary
privileges, you have several options:

@itemize @bullet
@item
Info files don't actually need to be installed before being used.  You
can feed a file name to the @code{Info-goto-node} command (invoked by
pressing @key{g} in Info mode) by typing the name of the file in
parentheses.  This goes to the node named ``Top'' in that file.  For
example, to view a Info file named @file{@var{info-file}} in your home
directory, you can type this:

@example
@kbd{C-h i g (~/@var{info-file}) @key{RET}}
@end example

@item
You can create your own Info directory.  You can tell Emacs where that
Info directory is by adding its pathname to the value of the variable
@code{Info-default-directory-list}.  For example, to use a private Info
directory which is a subdirectory of your home directory named @file{Info},
you could put this in your @file{.emacs} file:

@lisp
(setq Info-default-directory-list
      (cons "~/Info" Info-default-directory-list))
@end lisp

You will need a top-level Info file named @file{dir} in this directory
which has everything the system @file{dir} file has in it, except it should
list only entries for Info files in that directory.  You might not need
it if all files in this directory were referenced by other @file{dir}
files.  The node lists from all @file{dir} files in
@code{Info-default-directory-list} are merged by the Info system.

@end itemize

@node Printing a Texinfo file, Viewing Info files outside of Emacs, Installing Texinfo documentation, Getting help
@section How do I print a Texinfo file?
@cindex Printing a Texinfo file
@cindex Texinfo file, printing
@cindex Printing documentation

You can't get nicely printed output from Info files; you must still have
the original Texinfo source file for the manual you want to print.

Assuming you have @TeX{} installed on your system, follow these steps:

@enumerate

@item
Make sure the first line of the Texinfo file looks like this:

@example
\input texinfo
@end example

You may need to change @samp{texinfo} to the full pathname of the
@file{texinfo.tex} file, which comes with Emacs as
@file{man/texinfo.tex} (or copy or link it into the current directory).

@item
Type @kbd{texi2dvi @var{texinfo-source}}, where @var{texinfo-source} is
the name of the Texinfo source file for which you want to produce a
printed copy.

The @samp{texi2dvi} script is part of the GNU Texinfo distribution
(@pxref{Installing Texinfo documentation}).

@item
Print the DVI file @file{@var{texinfo-source}.dvi} in the normal way for
printing DVI files at your site.  For example, if you have a PostScript
printer, run the @code{dvips} program to print the DVI file on that
printer.

@end enumerate

To get more general instructions, retrieve the latest Texinfo package
(@pxref{Installing Texinfo documentation}).

@node Viewing Info files outside of Emacs, Informational files for Emacs, Printing a Texinfo file, Getting help
@section Can I view Info files without using Emacs?
@cindex Viewing Info files
@cindex Info file viewers
@cindex Alternative Info file viewers

Yes.  Here are some alternative programs:

@itemize @bullet

@item
@code{info}, a stand-alone version of the Info program, comes as part of
the Texinfo package.  @xref{Installing Texinfo documentation}, for
details.

@item
Xinfo, a stand-alone version of the Info program that runs under X
Window system.  You can get it at
@uref{ftp://ftp.gnu.org/pub/gnu/xinfo/xinfo-1.01.01.tar.gz} and all
mirrors of @samp{ftp.gnu.org} (see @ref{Current GNU distributions}, for a
list of mirrors).

@item
Tkinfo, an Info viewer that runs under X Window system and uses Tcl/Tk.
You can get Tkinfo at
@uref{http://math-www.uni-paderborn.de/~axel/tkinfo/}.

@end itemize

@node Informational files for Emacs, Help installing Emacs, Viewing Info files outside of Emacs, Getting help
@section What informational files are available for Emacs?
@cindex Informational files included with Emacs
@cindex Files included with Emacs
@cindex @file{COPYING}, description of file
@cindex @file{DISTRIB}, description of file
@cindex @file{FTP}, description of file
@cindex @file{GNU}, description of file
@cindex @file{INTERVIEW}, description of file
@cindex @file{LPF}, description of file
@cindex @file{MACHINES}, description of file
@cindex @file{MAILINGLISTS}, description of file
@cindex @file{NEWS}, description of file
@cindex @file{SERVICE}, description of file
@cindex @file{SUN-SUPPORT}, description of file

This isn't a frequently asked question, but it should be!  A variety of
informational files about Emacs and relevant aspects of the GNU project
are available for you to read.

The following files are available in the @file{etc} directory of the
Emacs distribution (see @ref{File-name conventions}, if you're not sure
where that is).

@table @file

@item COPYING
Emacs General Public License

@item DISTRIB
Emacs Availability Information, including the popular "Free Software
Foundation Order Form"

@item FTP
How to get GNU Software by Internet FTP or by UUCP

@item GNU
The GNU Manifesto

@item INTERVIEW
Richard Stallman discusses his public-domain UNIX-compatible software
system with BYTE editors

@item LPF
Why you should join the League for Programming Freedom

@item MACHINES
Status of Emacs on Various Machines and Systems

@item MAILINGLISTS
GNU Project Electronic Mailing Lists

@item NEWS
Emacs news, a history of recent user-visible changes

@item SERVICE
GNU Service Directory

@item SUN-SUPPORT
including "Using Emacstool with GNU Emacs"

@end table

Latest versions of the above files also available at

@uref{ftp://ftp.gnu.org/pub/gnu/GNUinfo/}

More GNU information, including back issues of the @cite{GNU's
Bulletin}, are at

@uref{http://www.gnu.org/bulletins/bulletins.html} and

@uref{http://www.cs.pdx.edu/~trent/gnu/gnu.html}

@node Help installing Emacs, Obtaining the FAQ, Informational files for Emacs, Getting help
@section Where can I get help in installing Emacs?
@cindex Installation help
@cindex Help installing Emacs

@xref{Installing Emacs}, for some basic installation hints, and see
@ref{Problems building Emacs}, or @ref{Linking with -lX11 fails}, if you
have problems with the installation.

The file @file{etc/SERVICE} (see @ref{File-name conventions}, if you're
not sure where that is) lists companies and individuals willing to sell
you help in installing or using Emacs.  An up-to-date version this file
is available on @samp{ftp.gnu.org} (@pxref{Informational files for
Emacs}).

@node Obtaining the FAQ,  , Help installing Emacs, Getting help
@section Where can I get the latest version of this FAQ?
@cindex FAQ, obtaining the
@cindex Latest FAQ version, obtaining the
@cindex Retrieving the latest FAQ version
@cindex E-mail, retrieving the FAQ via
@cindex Web, reading the FAQ on the

The Emacs FAQ is available in several ways:

@itemize @bullet

@item
Inside of Emacs itself.  You can get it from selecting the @samp{Emacs
FAQ} option from the @samp{Help} menu of the Emacs menu bar at the top
of any Emacs frame, or by typing @kbd{C-h F} (@kbd{M-x view-emacs-FAQ}).

@item
Via USENET.  If you can read news, the FAQ should be available in your
news spool, in both the @uref{news:gnu.emacs.help} and
@uref{news:comp.emacs} newsgroups.  Every news reader should allow you
to read any news article that is still in the news spool, even if you
have read the article before.  You may need to read the instructions for
your news reader to discover how to do this.  In @file{rn}, this command
will do this for you at the article selection level:

@example
?GNU Emacs Frequently Asked Questions?rc:m
@end example

In Gnus, you should type @kbd{C-u C-x C-s} from the @file{*Summary*}
buffer or @kbd{C-u @key{SPC}} from the @file{*Newsgroup*} buffer to view
all articles in a newsgroup.

If the FAQ articles have expired and have been deleted from your news
spool, it might (or might not) do some good to complain to your news
administrator, because the most recent FAQ should not expire for a
while.

@item
Via HTTP or FTP.  You can always fetch the latest FAQ from

@uref{http://www.lerner.co.il/emacs/} and

@uref{ftp://ftp.lerner.co.il/pub/emacs/}

@item
In the Emacs distribution.  Since Emacs 18.56, the FAQ at the time
of release has been part of the Emacs distribution as either
@file{etc/FAQ} or @file{man/faq.texi} (@pxref{File-name conventions}).

@item
Via the World Wide Web.  A hypertext version is available at

@uref{http://www.lerner.co.il/emacs/}

@item
Via anonymous ftp and e-mail from @file{rtfm.mit.edu} (and its mirror in
Europe), the main repository for FAQs and other items posted to
news.answers.  The Emacs FAQs are available at

@uref{ftp://rtfm.mit.edu/pub/usenet/comp.emacs/} and

@uref{ftp://ftp.uni-paderborn.de/pub/doc/FAQ/comp/emacs/}

If you do not have access to anonymous FTP, you can access the archives
using the @file{rtfm.mit.edu} mail server.  The Emacs FAQ can be
retrieved by sending mail to @email{mail-server@@rtfm.mit.edu} with a
blank subject and containing

@example
send usenet/news.answers/GNU-Emacs-FAQ/diffs
send usenet/news.answers/GNU-Emacs-FAQ/part1
send usenet/news.answers/GNU-Emacs-FAQ/part2
send usenet/news.answers/GNU-Emacs-FAQ/part3
send usenet/news.answers/GNU-Emacs-FAQ/part4
send usenet/news.answers/GNU-Emacs-FAQ/part5
@end example

For more information, send email to @email{mail-server@@rtfm.mit.edu}
with "help" and "index" in the body on separate lines.

@item
As the very last resort, you can e-mail a request to
@email{emacs-faq@@lerner.co.il}.  Don't do this unless you have made a
good-faith effort to obtain the FAQ list via one of the methods listed
above.

@end itemize

@c ------------------------------------------------------------
@node    Status of Emacs, Common requests, Getting help, Top
@chapter Status of Emacs
@cindex Status of Emacs

This chapter gives you basic information about Emacs, including its
latest version status.

@menu
* Origin of the term Emacs::
* Latest version of Emacs::
* New in Emacs 20::
* New in Emacs 21::
@end menu

@node Origin of the term Emacs, Latest version of Emacs, Status of Emacs, Status of Emacs
@section Where does the name ``Emacs'' come from?
@cindex Origin of the term ``Emacs''
@cindex Emacs name origin
@cindex TECO
@cindex Original version of Emacs

Emacs originally was an acronym for Editor MACroS.  RMS says he ``picked
the name Emacs because @key{E} was not in use as an abbreviation on ITS at
the time.''  The first Emacs was a set of macros written in 1976 at MIT
by RMS for the editor TECO (Text Editor and COrrector, originally Tape
Editor and COrrector) under ITS on a PDP-10.  RMS had already extended
TECO with a ``real-time'' full-screen mode with reprogrammable keys.
Emacs was started by @email{gls@@east.sun.com, Guy Steele} as a project
to unify the many divergent TECO command sets and key bindings at MIT,
and completed by RMS.

Many people have said that TECO code looks a lot like line noise; you
can read more at @uref{news:alt.lang.teco}.  Someone has written a TECO
implementation in Emacs Lisp (to find it, see @ref{Packages that do not
come with Emacs}); it would be an interesting project to run the
original TECO Emacs inside of Emacs.

@cindex Why Emacs?
For some not-so-serious alternative reasons for Emacs to have that
name, check out the file @file{etc/JOKES} (@pxref{File-name
conventions}).

@node Latest version of Emacs, New in Emacs 20, Origin of the term Emacs, Status of Emacs
@section What is the latest version of Emacs?
@cindex Version, latest
@cindex Latest version of Emacs

Emacs @value{VER} is the current version as of this writing.

@node New in Emacs 20,  New in Emacs 21, Latest version of Emacs, Status of Emacs
@section What is different about Emacs 20?
@cindex Differences between Emacs 19 and Emacs 20
@cindex Emacs 20, new features in

To find out what has changed in recent versions, type @kbd{C-h n}
(@kbd{M-x view-emacs-news}).  The oldest changes are at the bottom of
the file, so you might want to read it starting there, rather than at
the top.

The differences between Emacs versions 18 and 19 was rather dramatic;
the introduction of frames, faces, and colors on windowing systems was
obvious to even the most casual user.

There are differences between Emacs versions 19 and 20 as well, but many
are more subtle or harder to find.  Among the changes are the inclusion
of MULE code for languages that use non-Latin characters and for mixing
several languages in the same document; the ``Customize'' facility for
modifying variables without having to use Lisp; and automatic conversion
of files from Macintosh, Microsoft, and Unix platforms.

A number of older Lisp packages, such as Gnus, Supercite and the
calendar/diary, have been updated and enhanced to work with Emacs 20,
and are now included with the standard distribution.


@node New in Emacs 21, , New in Emacs 20, Status of Emacs
@section What is different about Emacs 21?
@cindex Differences between Emacs 20 and Emacs 21
@cindex Emacs 21, new features in
@cindex Recently introduced features

@cindex Variable-size fonts
@cindex Toolbar support
Emacs 21 features a thorough rewrite of the display engine.  The new
display engine supports variable-size fonts, images, and can play sounds
on platforms which support that.  As a result, the visual appearance of
Emacs, when it runs on a windowed display, is much more reminiscent of
modern GUI programs, and includes 3D widgets (used for the mode line and
the scroll bars), a configurable and extensible toolbar, tooltips
(a.k.a.@: balloon help), and other niceties.

@cindex Colors on text-only terminals
@cindex TTY colors
In addition, Emacs 21 supports faces on text-only terminals.  This means
that you can now have colors when you run Emacs on a GNU/Linux console
and on @code{xterm} with @kbd{emacs -nw}.

@c ------------------------------------------------------------
@node    Common requests, Bugs and problems, Status of Emacs, Top
@chapter Common requests
@cindex Common requests

@menu
* Setting up a customization file::
* Debugging a customization file::
* Colors on a TTY::
* Displaying the current line or column::
* Displaying the current file name in the titlebar::
* Turning on abbrevs by default::
* Turning on auto-fill by default::
* Associating modes with files::
* Working with unprintable characters::
* Highlighting a region::
* Controlling case sensitivity::
* Wrapping words automatically::
* Spell-checkers::
* Checking TeX and *roff documents::
* Changing load-path::
* Using an already running Emacs process::
* Compiler error messages::
* Indenting switch statements::
* Customizing C and C++ indentation::
* Horizontal scrolling::
* Overwrite mode::
* Turning off beeping::
* Turning the volume down::
* Automatic indentation::
* Matching parentheses::
* Hiding #ifdef lines::
* Repeating commands::
* Valid X resources::
* Evaluating Emacs Lisp code::
* Changing the length of a Tab::
* Inserting > at the beginning of each line::
* Underlining paragraphs::
* Repeating a command as many times as possible::
* Forcing the cursor to remain in the same column::
* Forcing Emacs to iconify itself::
* Using regular expressions::
* Replacing text across multiple files::
* Documentation for etags::
* Disabling backups::
* Disabling auto-save-mode::
* Going to a line by number::
* Modifying pull-down menus::
* Deleting menus and menu options::
* Turning on syntax highlighting::
* Scrolling only one line::
* Replacing highlighted text::
* Editing MS-DOS files::
* Filling paragraphs with a single space::
* Escape sequences in shell output::
@end menu

@node Setting up a customization file, Colors on a TTY, Common requests, Common requests
@section How do I set up a @file{.emacs} file properly?
@cindex @file{.emacs} file, setting up
@cindex @file{.emacs} file, locating
@cindex Init file, setting up
@cindex Customization file, setting up

@inforef{Init File, Init File, emacs}.

In general, new Emacs users should not have @file{.emacs} files, because
it causes confusing non-standard behavior.  Then they send questions to
@email{help-gnu-emacs@@gnu.org} asking why Emacs isn't behaving as
documented.

Beginning with version 20.1, Emacs includes the new Customize
facility, which can be invoked using @kbd{M-x customize @key{RET}}.
This allows users who are unfamiliar with Emacs Lisp to modify their
@file{.emacs} files in a relatively straightforward way, using menus
rather than Lisp code.  Not all packages support Customize as of this
writing, but the number is growing fairly steadily.

While Customize might indeed make it easier to configure Emacs,
consider taking a bit of time to learn Emacs Lisp and modifying your
@file{.emacs} directly.  Simple configuration options are described
rather completely in @inforef{Init File, Init File, emacs}, for users
interested in performing frequently requested, basic tasks.

Sometimes users are unsure as to where their @file{.emacs} file should
be found.  Visiting the file as @file{~/.emacs} from Emacs will find
the correct file.

@node Colors on a TTY, Debugging a customization file, Setting up a customization file, Common requests
@section How do I get colors and syntax highlighting on a TTY?
@cindex Colors on a TTY
@cindex Syntax highlighting on a TTY
@cindex Console, colors

In Emacs 21.1 and later, colors and faces are supported in non-windowed mode,
i.e.@: on Unix and GNU/Linux text-only terminals and consoles, and when
invoked as @samp{emacs -nw} on X and MS-Windows.  (Colors and faces were
supported in the MS-DOS port since Emacs 19.29.)  Emacs automatically
detects color support at startup and uses it if available.  If you think
that your terminal supports colors, but Emacs won't use them, check the
@code{termcap} entry for your display type for color-related
capabilities.

The command @kbd{M-x list-colors-display} pops up a window which
exhibits all the colors Emacs knows about on the current display.

Syntax highlighting is usually turned off by default; see @ref{Turning
on syntax highlighting}, for instructions how to turn it on.

@node Debugging a customization file, Displaying the current line or column, Colors on a TTY, Common requests
@section How do I debug a @file{.emacs} file?
@cindex Debugging @file{.emacs} file
@cindex @file{.emacs} debugging
@cindex Init file debugging
@cindex @samp{-debug-init} option

Start Emacs with the @samp{-debug-init} command-line option.  This
enables the Emacs Lisp debugger before evaluating your @file{.emacs}
file, and places you in the debugger if something goes wrong.  The top
line in the @file{trace-back} buffer will be the error message, and the
second or third line of that buffer will display the Lisp code from your
@file{.emacs} file that caused the problem.

You can also evaluate an individual function or argument to a function
in your @file{.emacs} file by moving the cursor to the end of the
function or argument and typing @kbd{C-x C-e} (@kbd{M-x
eval-last-sexp}).

Use @kbd{C-h v} (@kbd{M-x describe-variable}) to check the value of
variables which you are trying to set or use.

@node Displaying the current line or column, Displaying the current file name in the titlebar, Debugging a customization file, Common requests
@section How do I make Emacs display the current line (or column) number?
@cindex @code{line-number-mode}
@cindex Displaying the current line or column
@cindex Line number, displaying the current
@cindex Column, displaying the current
@cindex @code{mode-line-format}

To have Emacs automatically display the current line number of the point
in the mode line, do @kbd{M-x line-number-mode}.  You can also put the
form

@lisp
(setq line-number-mode t)
@end lisp

@noindent
in your @file{.emacs} file to achieve this whenever you start Emacs.
(Line number display is on by default, unless your site-specific
initialization disables it.) Note that Emacs will not display the line
number if the buffer's size in bytes is larger than the value of the
variable @code{line-number-display-limit}.

As of Emacs 20, you can similarly display the current column with
@kbd{M-x column-number-mode}, or by putting the form

@lisp
(setq column-number-mode t)
@end lisp

@noindent
in your @file{.emacs} file.

The @code{"%c"} format specifier in the variable @code{mode-line-format}
will insert the current column's value into the mode line.  See the
documentation for @code{mode-line-format} (using @kbd{C-h v
mode-line-format @key{RET}}) for more information on how to set and use
this variable.

Users of all Emacs versions can display the current column using the
@samp{column} package written by @email{abraham@@dina.kvl.dk, Per
Abrahamsen}.  @xref{Packages that do not come with Emacs}, for
instructions on how to get it.

@cindex Set number capability in @code{vi} emulators
None of the @code{vi} emulation modes provide the ``set number''
capability of @code{vi} (as far as we know).  The @samp{setnu} package
written by @email{kyle@@wonderworks.com, Kyle Jones} provides this
feature.  So too does @samp{wb-line-number}, written by
@email{naoki.y.nakamura@@nifty.com, Naoki Nakamura}.

@node Displaying the current file name in the titlebar, Turning on abbrevs by default, Displaying the current line or column, Common requests
@section How can I modify the titlebar to contain the current file name?
@cindex Titlebar, displaying the current file name in
@cindex File name, displaying in the titlebar
@cindex @code{frame-title-format}

The contents of an Emacs frame's titlebar is controlled by the variable
@code{frame-title-format}, which has the same structure as the variable
@code{mode-line-format}.  (Use @kbd{C-h v} or @kbd{M-x
describe-variable} to get information about one or both of these
variables.)

By default, the titlebar for a frame does contain the name of the buffer
currently being visited, except if there is a single frame.  In such a
case, the titlebar contains Emacs invocation name and the name of the
machine at which Emacs was invoked.  This is done by setting
@code{frame-title-format} to the default value of

@lisp
(multiple-frames "%b" ("" invocation-name "@@" system-name))
@end lisp

To modify the behavior such that frame titlebars contain the buffer's
name regardless of the number of existing frames, include the following
in your @file{.emacs}:

@lisp
(setq frame-title-format "%b")
@end lisp

@node Turning on abbrevs by default, Turning on auto-fill by default, Displaying the current file name in the titlebar, Common requests
@section How do I turn on abbrevs by default just in mode @var{mymode}?
@cindex Abbrevs, turning on by default

Put this in your @file{.emacs} file:

@lisp
(condition-case ()
   (quietly-read-abbrev-file)
  (file-error nil))

(add-hook '@var{mymode}-mode-hook
          (lambda ()
           (setq abbrev-mode t)))
@end lisp

@node Turning on auto-fill by default, Associating modes with files, Turning on abbrevs by default, Common requests
@section How do I turn on @code{auto-fill-mode} by default?
@cindex @code{auto-fill-mode}, activating automatically
@cindex Filling automatically
@cindex Automatic entry to @code{auto-fill-mode}

To turn on @code{auto-fill-mode} just once for one buffer, use @kbd{M-x
auto-fill-mode}.

To turn it on for every buffer in a certain mode, you must use the hook
for that mode.  For example, to turn on @code{auto-fill} mode for all
text buffers, including the following in your @file{.emacs} file:

@lisp
(add-hook 'text-mode-hook 'turn-on-auto-fill)
@end lisp

If you want @code{auto-fill} mode on in all major modes, do this:

@lisp
(setq-default auto-fill-function 'do-auto-fill)
@end lisp

@node Associating modes with files, Working with unprintable characters, Turning on auto-fill by default, Common requests
@section How do I make Emacs use a certain major mode for certain files?
@cindex Associating modes with files
@cindex File extensions and modes
@cindex @code{auto-mode-alist}, modifying
@cindex Modes, associating with file extensions

If you want to use a certain mode @var{foo} for all files whose names end
with the extension @file{.@var{bar}}, this will do it for you:

@lisp
(setq auto-mode-alist (cons '("\\.@var{bar}\\'" . @var{foo}-mode) auto-mode-alist))
@end lisp

Otherwise put this somewhere in the first line of any file you want to
edit in the mode @var{foo} (in the second line, if the first line begins
with @samp{#!}):

@example
-*- @var{foo} -*-
@end example

@cindex Major mode for shell scripts
Beginning with Emacs 19, the variable @code{interpreter-mode-alist}
specifies which mode to use when loading a shell script.  (Emacs
determines which interpreter you're using by examining the first line of
the script.)  This feature only applies when the file name doesn't
indicate which mode to use.  Use @kbd{C-h v} (or @kbd{M-x
describe-variable}) on @code{interpreter-mode-alist} to learn more.

@node Working with unprintable characters, Highlighting a region, Associating modes with files, Common requests
@section How do I search for, delete, or replace unprintable (eight-bit or control) characters?
@cindex Unprintable characters, working with
@cindex Working with unprintable characters
@cindex Control characters, working with
@cindex Eight-bit characters, working with
@cindex Searching for unprintable characters
@cindex Regexps and unprintable characters

To search for a single character that appears in the buffer as, for
example, @samp{\237}, you can type @kbd{C-s C-q 2 3 7}.  (This assumes
the value of @code{search-quote-char} is 17 (i.e., @kbd{C-q}).)
Searching for @strong{all} unprintable characters is best done with a
regular expression (@dfn{regexp}) search.  The easiest regexp to use for
the unprintable chars is the complement of the regexp for the printable
chars.

@itemize @bullet

@item
Regexp for the printable chars: @samp{[\t\n\r\f -~]}

@item
Regexp for the unprintable chars: @samp{[^\t\n\r\f -~]}

@end itemize

To type these special characters in an interactive argument to
@code{isearch-forward-regexp} or @code{re-search-forward}, you need to
use @kbd{C-q}.  (@samp{\t}, @samp{\n}, @samp{\r}, and @samp{\f} stand
respectively for @key{TAB}, @key{LFD}, @key{RET}, and @kbd{C-l}.)  So,
to search for unprintable characters using @code{re-search-forward}:

@kbd{M-x re-search-forward @key{RET} [^ @key{TAB} C-q @key{LFD} C-q @key{RET} C-q C-l @key{SPC} -~] @key{RET}}

Using @code{isearch-forward-regexp}:

@kbd{C-M-s [^ @key{TAB} @key{LFD} C-q @key{RET} C-q C-l @key{SPC} -~]}

To delete all unprintable characters, simply use replace-regexp:

@kbd{M-x replace-regexp @key{RET} [^ @key{TAB} C-q @key{LFD} C-q @key{RET} C-q C-l @key{SPC} -~] @key{RET} @key{RET}}

Replacing is similar to the above.  To replace all unprintable
characters with a colon, use:

M-x replace-regexp @key{RET} [^ @key{TAB} C-q @key{LFD} C-q @key{RET} C-q C-l @key{SPC} -~] @key{RET} : @key{RET}

@itemize @bullet

@item
You don't need to quote @key{TAB} with either isearch or typing
something in the minibuffer.

@end itemize

@node Highlighting a region, Controlling case sensitivity, Working with unprintable characters, Common requests
@section How can I highlight a region of text in Emacs?
@cindex Highlighting text
@cindex Text, highlighting
@cindex @code{transient-mark-mode}
@cindex Region, highlighting a

You can cause the region to be highlighted when the mark is active by
including

@lisp
(transient-mark-mode t)
@end lisp

@noindent
in your @file{.emacs} file.  (Also see @ref{Turning on syntax
highlighting}.)

@node Controlling case sensitivity, Wrapping words automatically, Highlighting a region, Common requests
@section How do I control Emacs's case-sensitivity when searching/replacing?
@cindex @code{case-fold-search}
@cindex Case sensitivity of searches
@cindex Searching without case sensitivity
@cindex Ignoring case in searches

For searching, the value of the variable @code{case-fold-search}
determines whether they are case sensitive:

@lisp
(setq case-fold-search nil) ; make searches case sensitive
(setq case-fold-search t)   ; make searches case insensitive
@end lisp

@cindex Case sensitivity in replacements
@cindex Replacing, and case sensitivity
@cindex @code{case-replace}
Similarly, for replacing, the variable @code{case-replace} determines
whether replacements preserve case.

To change the case sensitivity just for one major mode, use the major
mode's hook.  For example:

@lisp
(add-hook '@var{foo}-mode-hook
          (lambda ()
           (setq case-fold-search nil)))
@end lisp

@node Wrapping words automatically, Spell-checkers, Controlling case sensitivity, Common requests
@section How do I make Emacs wrap words for me?
@cindex Wrapping word automatically
@cindex Wrapping lines
@cindex Line wrap
@cindex @code{auto-fill-mode}, introduction to
@cindex Maximum line width, default value
@cindex @code{fill-column}, default value

Use @code{auto-fill-mode}, activated by typing @kbd{M-x auto-fill-mode}.
The default maximum line width is 70, determined by the variable
@code{fill-column}.  To learn how to turn this on automatically, see
@ref{Turning on auto-fill by default}.

@node Spell-checkers, Checking TeX and *roff documents, Wrapping words automatically, Common requests
@section Where can I get a better spelling checker for Emacs?
@cindex Checking spelling
@cindex Spelling, checking text documents

Use Ispell.  @xref{Ispell}.

@node Checking TeX and *roff documents, Changing load-path, Spell-checkers, Common requests
@section How can I spell-check @TeX{} or *roff documents?
@cindex Spelling, checking @TeX{} documents
@cindex @TeX{} documents, checking spelling in

Use Ispell.  Ispell can handle @TeX{} and *roff documents.
@xref{Ispell}.

@node Changing load-path, Using an already running Emacs process, Checking TeX and *roff documents, Common requests
@section How do I change @code{load-path}?
@cindex @code{load-path}, modifying
@cindex Modifying @code{load-path}
@cindex Adding to @code{load-path}

In general, you should only add to the @code{load-path}.  You can add
directory @var{/dir/subdir} to the load path like this:

@lisp
(setq load-path (cons "/dir/subdir/" load-path))
@end lisp

To do this relative to your home directory:

@lisp
(setq load-path (cons "~/mysubdir/" load-path)
@end lisp

@node Using an already running Emacs process, Compiler error messages, Changing load-path, Common requests
@section How do I use an already running Emacs from another window?
@cindex @code{emacsclient}
@cindex Emacs server functions
@cindex Using an existing Emacs process

@code{emacsclient}, which comes with Emacs, is for editing a file using
an already running Emacs rather than starting up a new Emacs.  It does
this by sending a request to the already running Emacs, which must be
expecting the request.

@itemize @bullet

@item
Setup:

Emacs must have executed the @code{server-start} function for
@samp{emacsclient} to work.  This can be done either by a command line
option:

@example
emacs -f server-start
@end example

or by invoking @code{server-start} from @file{.emacs}:

@lisp
(if (@var{some conditions are met}) (server-start))
@end lisp

When this is done, Emacs creates a Unix domain socket.
The socket is either named @file{.emacs_server}, in the user's home directory,
or @file{esrv-@var{userid}-@var{systemname}}, in the @file{/tmp}
directory, depending on your system.  See @code{server-socket-name}.

To get your news reader, mail reader, etc., to invoke
@samp{emacsclient}, try setting the environment variable @code{EDITOR}
(or sometimes @code{VISUAL}) to the value @samp{emacsclient}.  You may
have to specify the full pathname of the @samp{emacsclient} program
instead.  Examples:

@example
# csh commands:
setenv EDITOR emacsclient

# using full pathname
setenv EDITOR /usr/local/emacs/etc/emacsclient

# sh command:
EDITOR=emacsclient ; export EDITOR
@end example

@item
Normal use:

When @samp{emacsclient} is run, it connects to the @file{.emacs_server}
socket and passes its command line options to @samp{server}.  When
@samp{server} receives these requests, it sends this information to the
the Emacs process, which at the next opportunity will visit the files
specified.  (Line numbers can be specified just like with Emacs.)  The
user will have to switch to the Emacs window by hand.  When the user is
done editing a file, the user can type @kbd{C-x #} (or @kbd{M-x
server-edit}) to indicate this.  If there is another buffer requested by
@code{emacsclient}, Emacs will switch to it; otherwise
@code{emacsclient} will exit, signaling the calling program to continue.

@samp{emacsclient} and @samp{server} must be running on machines which
share the same filesystem for this to work.  The pathnames that
@samp{emacsclient} specifies should be correct for the filesystem that
the Emacs process sees.  The Emacs process should not be suspended at
the time @samp{emacsclient} is invoked.  On Unix and GNU/Linux systems,
@samp{emacsclient} should either be invoked from another X window, or
from a shell window inside Emacs itself, or from another interactive
session, e.g., by means of a @code{screen} program.

@cindex @code{gnuserv}
There is an enhanced version of @samp{emacsclient}/server called
@samp{gnuserv}, written by @email{ange@@hplb.hpl.hp.com, Andy Norman}
(@pxref{Packages that do not come with Emacs}).  @samp{gnuserv} uses
Internet domain sockets, so it can work across most network connections.
It also supports the execution of arbitrary Emacs Lisp forms and does
not require the client program to wait for completion.

The alpha version of an enhanced @samp{gnuserv} is available at

@uref{ftp://ftp.wellfleet.com/netman/psmith/emacs/gnuserv-2.1alpha.tar.gz}

The version available from @uref{http://meltin.net/hacks/emacs/} is
more recent, and has been tested with Emacs 21.2.

@end itemize

@node Compiler error messages, Indenting switch statements, Using an already running Emacs process, Common requests
@section How do I make Emacs recognize my compiler's funny error messages?
@cindex Compiler error messages, recognizing
@cindex Recognizing non-standard compiler errors
@cindex Regexps for recognizing compiler errors
@cindex Errors, recognizing compiler

The variable @code{compilation-error-regexp-alist} helps control how
Emacs parses your compiler output.  It is a list of triplets of the form:
@code{(@var{regexp} @var{file-idx} @var{line-idx})}, where @var{regexp},
@var{file-idx} and @var{line-idx} are strings.  To help determine what
the constituent elements should be, load @file{compile.el} and then type
@kbd{C-h v compilation-error-regexp-alist @key{RET}} to see the current
value.  A good idea is to look at @file{compile.el} itself as the
comments included for this variable are quite useful---the regular
expressions required for your compiler's output may be very close to one
already provided.  Once you have determined the proper regexps, use the
following to inform Emacs of your changes:

@lisp
(setq compilation-error-regexp-alist
      (cons '(@var{regexp} @var{file-idx} @var{line-idx})
         compilation-error-regexp-alist))
@end lisp

@node Indenting switch statements, Customizing C and C++ indentation, Compiler error messages, Common requests
@section How do I change the indentation for @code{switch}?
@cindex @code{switch}, indenting
@cindex Indenting of @code{switch}

Many people want to indent their @code{switch} statements like this:

@example
f()
@{
  switch(x) @{
    case A:
      x1;
      break;
    case B:
      x2;
      break;
    default:
      x3;
  @}
@}
@end example

The solution at first appears to be: set @code{c-indent-level} to 4 and
@code{c-label-offset} to -2.  However, this will give you an indentation
spacing of four instead of two.

The @emph{real} solution is to use @code{cc-mode} (the default mode for
C programming in Emacs 20 and later) and add the following line to yoyr
@file{.emacs}:

@lisp
(c-set-offset 'case-label '+)
@end lisp

There appears to be no way to do this with the old @code{c-mode}.

@node Customizing C and C++ indentation, Horizontal scrolling, Indenting switch statements, Common requests
@section How to customize indentation in C, C@t{++}, and Java buffers?
@cindex Indentation, how to customize
@cindex Customize indentation

The Emacs @code{cc-mode} features an interactive procedure for
customizing the indentation style, which is fully explained in the
@cite{CC Mode} manual that is part of the Emacs distribution, see
@ref{Customizing Indentation, , Customization Indentation, ccmode,
The CC Mode Manual}.  Here's a short summary of the procedure:

@enumerate
@item
Go to the beginning of the first line where you don't like the
indentation and type @kbd{C-c C-o}.  Emacs will prompt you for the
syntactic symbol; type @key{RET} to accept the default it suggests.

@item
Emacs now prompts for the offset of this syntactic symbol, showing the
default (the current definition) inside parentheses.  You can choose
one of these:

@table @code
@item 0
No extra indentation.
@item +
Indent one basic offset.
@item -
Outdent one basic offset.
@item ++
Indent two basic offsets
@item --
Outdent two basic offsets.
@item *
Indent half basic offset.
@item /
Outdent half basic offset.
@end table

@item
After choosing one of these symbols, type @kbd{C-c C-q} to reindent
the line or the block according to what you just specified.

@item
If you don't like the result, go back to step 1.  Otherwise, add the
following line to your @file{.emacs}:

@lisp
(c-set-offset '@var{syntactic-symbol} @var{offset})
@end lisp

@noindent
where @var{syntactic-symbol} is the name Emacs shows in the minibuffer
when you type @kbd{C-c C-o} at the beginning of the line, and
@var{offset} is one of the indentation symbols listed above (@code{+},
@code{/}, @code{0}, etc.) that you've chosen during the interactive
procedure.

@item
Go to the next line whose indentation is not to your liking and repeat
the process there.
@end enumerate

It is recommended to put all the resulting @code{(c-set-offset ...)}
customizations inside a C mode hook, like this:

@lisp
(defun my-c-mode-hook ()
  (c-set-offset ...)
  (c-set-offset ...))
(add-hook 'c-mode-hook 'my-c-mode-hook)
@end lisp

@noindent
Using @code{c-mode-hook} avoids the need to put a @w{@code{(require
'cc-mode)}} into your @file{.emacs} file, because @code{c-set-offset}
might be unavailable when @code{cc-mode} is not loaded.

Note that @code{c-mode-hook} runs for C source files only; use
@code{c++-mode-hook} for C@t{++} sources, @code{java-mode-hook} for
Java sources, etc.  If you want the same customizations to be in
effect in @emph{all} languages supported by @code{cc-mode}, use
@code{c-mode-common-hook}.

@node Horizontal scrolling, Overwrite mode, Customizing C and C++ indentation, Common requests
@section How can I make Emacs automatically scroll horizontally?
@cindex @code{hscroll-mode}
@cindex Horizontal scrolling
@cindex Scrolling horizontally

In Emacs 21 and later, this is on by default: if the variable
@code{truncate-lines} is non-@code{nil} in the current buffer, Emacs
automatically scrolls the display horizontally when point moves off the
left or right edge of the window.

In Emacs 20, use the @code{hscroll-mode}.  Here is some information from
the documentation, available by typing @kbd{C-h f hscroll-mode @key{RET}}:

Automatically scroll horizontally when the point moves off the
left or right edge of the window.

@itemize @minus
@item
Type @kbd{M-x hscroll-mode} to enable it in the current buffer.

@item
Type @kbd{M-x hscroll-global-mode} to enable it in every buffer.

@item
@code{turn-on-hscroll} is useful in mode hooks as in:

@lisp
(add-hook 'text-mode-hook 'turn-on-hscroll)
@end lisp

@item
@code{hscroll-margin} controls how close the cursor can get to the
edge of the window.

@item
@code{hscroll-step-percent} controls how far to jump once we decide to do so.
@end itemize

@node Overwrite mode, Turning off beeping, Horizontal scrolling, Common requests
@section How do I make Emacs "typeover" or "overwrite" instead of inserting?
@cindex @key{Insert}
@cindex @code{overwrite-mode}
@cindex Overwriting existing text
@cindex Toggling @code{overwrite-mode}

@kbd{M-x overwrite-mode} (a minor mode).  This toggles
@code{overwrite-mode} on and off, so exiting from @code{overwrite-mode}
is as easy as another @kbd{M-x overwrite-mode}.

On some systems, @key{Insert} toggles @code{overwrite-mode} on and off.

@node Turning off beeping, Turning the volume down, Overwrite mode, Common requests
@section How do I stop Emacs from beeping on a terminal?
@cindex Beeping, turning off
@cindex Visible bell
@cindex Bell, visible

@email{martin@@cc.gatech.edu, Martin R. Frank} writes:

Tell Emacs to use the @dfn{visible bell} instead of the audible bell,
and set the visible bell to nothing.

That is, put the following in your @code{TERMCAP} environment variable
(assuming you have one):

@example
... :vb=: ...
@end example

And evaluate the following Lisp form:

@example
(setq visible-bell t)
@end example

@node Turning the volume down, Automatic indentation, Turning off beeping, Common requests
@section How do I turn down the bell volume in Emacs running under X?
@cindex Bell, volume of
@cindex Volume of bell

On X Window system, you can adjust the bell volume and duration for all
programs with the shell command @code{xset}.

Invoking @code{xset} without any arguments produces some basic
information, including the following:

@example
usage:  xset [-display host:dpy] option ...
  To turn bell off:
      -b                b off               b 0
  To set bell volume, pitch and duration:
       b [vol [pitch [dur]]]          b on
@end example

@node Automatic indentation, Matching parentheses, Turning the volume down, Common requests
@section How do I tell Emacs to automatically indent a new line to the indentation of the previous line?
@cindex Indenting new lines
@cindex New lines, indenting of
@cindex Previous line, indenting according to
@cindex Text indentation

Such behavior is automatic in Emacs 20 and later.  From the
@file{etc/NEWS} file for Emacs 20.2:

@example
** In Text mode, now only blank lines separate paragraphs.  This makes
it possible to get the full benefit of Adaptive Fill mode in Text mode,
and other modes derived from it (such as Mail mode).  @key{TAB} in Text
mode now runs the command @code{indent-relative}; this makes a practical
difference only when you use indented paragraphs.

As a result, the old Indented Text mode is now identical to Text mode,
and is an alias for it.

If you want spaces at the beginning of a line to start a paragraph, use
the new mode, Paragraph Indent Text mode.
@end example

@cindex Prefixing lines
@cindex Fill prefix
If you have @code{auto-fill-mode} turned on (@pxref{Turning on auto-fill
by default}), you can tell Emacs to prefix every line with a certain
character sequence, the @dfn{fill prefix}.  Type the prefix at the
beginning of a line, position point after it, and then type @kbd{C-x .}
(@code{set-fill-prefix}) to set the fill prefix.  Thereafter,
auto-filling will automatically put the fill prefix at the beginning of
new lines, and @kbd{M-q} (@code{fill-paragraph}) will maintain any fill
prefix when refilling the paragraph.

If you have paragraphs with different levels of indentation, you will
have to set the fill prefix to the correct value each time you move to a
new paragraph.  There are many packages available to deal with this
(@pxref{Packages that do not come with Emacs}).  Look for ``fill'' and
``indent'' keywords for guidance.

@node Matching parentheses, Hiding #ifdef lines, Automatic indentation, Common requests
@section How do I show which parenthesis matches the one I'm looking at?
@cindex Parentheses, matching
@cindex @file{paren.el}
@cindex Highlighting matching parentheses
@cindex Pairs of parentheses, highlighting
@cindex Matching parentheses

As of version 19, Emacs comes with @file{paren.el}, which (when loaded)
will automatically highlight matching parentheses whenever point (i.e.,
the cursor) is located over one.  To load @file{paren.el} automatically,
include the line

@lisp
(require 'paren)
@end lisp

in your @file{.emacs} file.  @email{shutkoa@@ugsolutions.com, Alan Shutko}
reports that as of version 20.1, you must also call @code{show-paren-mode} in
your @file{.emacs} file:

@lisp
(show-paren-mode 1)
@end lisp

Customize will let you turn on @code{show-paren-mode}.  Use @kbd{M-x
customize-group @key{RET} paren-showing @key{RET}}.  From within
Customize, you can also go directly to the ``paren-showing'' group.

Alternatives to paren include:

@itemize @bullet

@item
If you're looking at a right parenthesis (or brace or bracket) you can
delete it and reinsert it.  Emacs will momentarily move the cursor to
the matching parenthesis.

@item
@kbd{C-M-f} (@code{forward-sexp}) and @kbd{C-M-b} (@code{backward-sexp})
will skip over one set of balanced parentheses, so you can see which
parentheses match.  (You can train it to skip over balanced brackets
and braces at the same time by modifying the syntax table.)

@cindex Show matching paren as in @code{vi}
@item
Here is some Emacs Lisp that will make the @key{%} key show the matching
parenthesis, like in @code{vi}.  In addition, if the cursor isn't over a
parenthesis, it simply inserts a % like normal.

@lisp
;; By an unknown contributor

(global-set-key "%" 'match-paren)

(defun match-paren (arg)
  "Go to the matching paren if on a paren; otherwise insert %."
  (interactive "p")
  (cond ((looking-at "\\s\(") (forward-list 1) (backward-char 1))
        ((looking-at "\\s\)") (forward-char 1) (backward-list 1))
        (t (self-insert-command (or arg 1)))))
@end lisp

@end itemize

@node Hiding #ifdef lines, Repeating commands, Matching parentheses, Common requests
@section In C mode, can I show just the lines that will be left after @code{#ifdef} commands are handled by the compiler?
@cindex @code{#ifdef}, selective display of
@cindex @code{hide-ifdef-mode}
@cindex Hiding @code{#ifdef} text
@cindex Selectively displaying @code{#ifdef} code

@kbd{M-x hide-ifdef-mode}.  (This is a minor mode.)  You might also want
to investigate @file{cpp.el}, which is distributed with Emacs.

@node Repeating commands, Valid X resources, Hiding #ifdef lines, Common requests
@section Is there an equivalent to the @code{.} (dot) command of vi?
@cindex Repeating commands as with @code{vi}
@cindex Command, repeat last
@cindex @code{.}, equivalent to @code{vi} command

(@code{.} is the redo command in @code{vi}.  It redoes the last
insertion/deletion.)

As of Emacs 20.3, there is indeed a @code{repeat} command (@kbd{C-x z})
that repeats the last command.  If you preface it with a prefix
argument, the prefix arg is applied to the command.

You can also type @kbd{C-x @key{ESC} @key{ESC}}
(@code{repeat-complex-command}) to reinvoke commands that used the
minibuffer to get arguments.  In @code{repeat-complex-command} you can
type @kbd{M-p} and @kbd{M-n} (and also up-arrow and down-arrow, if your
keyboard has these keys) to scan through all the different complex
commands you've typed.

To repeat a set of commands, use keyboard macros.  (@inforef{Keyboard
Macros, Keyboard Macros, emacs}.)

If you're really desperate for the @code{.} command, use VIPER, a
@code{vi} emulation mode which comes with Emacs, and which appears to
support it.  (@xref{VIPER}.)

@node Valid X resources, Evaluating Emacs Lisp code, Repeating commands, Common requests
@section What are the valid X resource settings (i.e., stuff in .Xdefaults)?
@cindex Resources, X
@cindex X resources
@cindex Setting X resources

@inforef{X Resources, X Resources, emacs}.

You can also use a resource editor, such as editres (for X11R5 and
onwards), to look at the resource names for the menu bar, assuming Emacs
was compiled with the X toolkit.

@node Evaluating Emacs Lisp code, Changing the length of a Tab, Valid X resources, Common requests
@section How do I execute ("evaluate") a piece of Emacs Lisp code?
@cindex Evaluating Lisp code
@cindex Lisp forms, evaluating

There are a number of ways to execute (@dfn{evaluate}, in Lisp lingo) an
Emacs Lisp @dfn{form}:

@itemize @bullet

@item
If you want it evaluated every time you run Emacs, put it in a file
named @file{.emacs} in your home directory.  This is known as ``your
@file{.emacs} file,'' and contains all of your personal customizations.

@item
You can type the form in the @file{*scratch*} buffer, and then type
@key{LFD} (or @kbd{C-j}) after it.  The result of evaluating the form
will be inserted in the buffer.

@item
In @code{emacs-lisp-mode}, typing @kbd{C-M-x} evaluates a top-level form
before or around point.

@item
Typing @kbd{C-x C-e} in any buffer evaluates the Lisp form immediately
before point and prints its value in the echo area.

@item
Typing @kbd{M-:} or @kbd{M-x eval-expression} allows you to type a Lisp
form in the minibuffer which will be evaluated once you press @key{RET}.

@item
You can use @kbd{M-x load-file} to have Emacs evaluate all the Lisp
forms in a file.  (To do this from Lisp use the function @code{load}
instead.)

The functions @code{load-library}, @code{eval-region},
@code{eval-current-buffer}, @code{require}, and @code{autoload} are also
useful; see @ref{Emacs Lisp documentation}, if you want to learn more
about them.

@end itemize

@node Changing the length of a Tab, Inserting > at the beginning of each line, Evaluating Emacs Lisp code, Common requests
@section How do I change Emacs's idea of the @key{TAB} character's length?
@cindex Tab length
@cindex Length of tab character
@cindex @code{default-tab-width}

Set the variable @code{default-tab-width}.  For example, to set
@key{TAB} stops every 10 characters, insert the following in your
@file{.emacs} file:

@lisp
(setq default-tab-width 10)
@end lisp

Do not confuse variable @code{tab-width} with variable
@code{tab-stop-list}.  The former is used for the display of literal
@key{TAB} characters.  The latter controls what characters are inserted
when you press the @key{TAB} character in certain modes.

@node Inserting > at the beginning of each line, Underlining paragraphs, Changing the length of a Tab, Common requests
@section How do I insert @samp{>} at the beginning of every line?
@cindex Prefix character, inserting in mail/news replies
@cindex Replies to mail/news, inserting a prefix character
@cindex @code{mail-yank-prefix}
@cindex Mail replies, inserting a prefix character
@cindex News replies, inserting a prefix character

To do this to an entire buffer, type @kbd{M-< M-x replace-regexp
@key{RET} ^ @key{RET} > @key{RET}}.

To do this to a region, use @code{string-insert-rectangle}.
Set the mark (@kbd{C-@key{SPC}}) at the beginning of the first line you
want to prefix, move the cursor to last line to be prefixed, and type
@kbd{M-x string-insert-rectangle @key{RET}}.  To do this for the whole
buffer, type @kbd{C-x h M-x string-insert-rectangle @key{RET}}.

If you are trying to prefix a yanked mail message with @samp{>}, you
might want to set the variable @code{mail-yank-prefix}.  Better yet, use
the Supercite package (@pxref{Supercite}), which provides flexible
citation for yanked mail and news messages; it is included in Emacs
since version 19.20.  @xref{Changing the included text prefix}, for
additional information.

@node Underlining paragraphs, Repeating a command as many times as possible, Inserting > at the beginning of each line, Common requests
@section How do I insert "_^H" before each character in a region to get an underlined paragraph?
@cindex Underlining a region of text
@cindex @code{underline-region}

Mark the region and then type @kbd{M-x underline-region @key{RET}}.

@node Repeating a command as many times as possible, Forcing the cursor to remain in the same column, Underlining paragraphs, Common requests
@section How do I repeat a command as many times as possible?
@cindex Repeating commands many times
@cindex Commands, repeating many times

Use @kbd{C-x (} and @kbd{C-x )} to make a keyboard macro that invokes
the command and then type @kbd{M-0 C-x e}.

Any messages your command prints in the echo area will be suppressed.

If you need to repeat a command a small number of times, you can use
@kbd{C-x z}, see @ref{Repeating commands}.

@node Forcing the cursor to remain in the same column, Forcing Emacs to iconify itself, Repeating a command as many times as possible, Common requests
@section How do I make Emacs behave like this: when I go up or down, the cursor should stay in the same column even if the line is too short?
@cindex @code{picture-mode}
@cindex Remaining in the same column, regardless of contents
@cindex Vertical movement in empty documents

@kbd{M-x picture-mode}.

@node Forcing Emacs to iconify itself, Using regular expressions, Forcing the cursor to remain in the same column, Common requests
@section How do I tell Emacs to iconify itself?
@cindex Iconification under the X Window System
@cindex X Window System and iconification
@cindex Suspending Emacs

@kbd{C-z} iconifies Emacs when running under X and suspends Emacs
otherwise.  @inforef{Frame Commands, Frame Commands, emacs}.

@node Using regular expressions, Replacing text across multiple files, Forcing Emacs to iconify itself, Common requests
@section How do I use regexps (regular expressions) in Emacs?
@cindex Regexps
@cindex Regular expressions
@cindex Differences between Unix and Emacs regexps
@cindex Unix regeps, differences from Emacs
@cindex Text strings, putting regexps in

@inforef{Regexps, Regexps, emacs}.

The @code{or} operator is @samp{\|}, not @samp{|}, and the grouping operators
are @samp{\(} and @samp{\)}.  Also, the string syntax for a backslash is
@samp{\\}.  To specify a regular expression like @samp{xxx\(foo\|bar\)}
in a Lisp string, use @samp{xxx\\(foo\\|bar\\)}.

Note the doubled backslashes!

@itemize @bullet

@item
Unlike in Unix @file{grep}, @file{sed}, etc., a complement character set
(@samp{[^...]})  can match a newline character (@key{LFD} a.k.a.@:
@kbd{C-j} a.k.a.@: @samp{\n}), unless newline is mentioned as one of the
characters not to match.

@item
The character syntax regexps (e.g., @samp{\sw}) are not
meaningful inside character set regexps (e.g., @samp{[aeiou]}).  (This
is actually typical for regexp syntax.)

@end itemize

@node Replacing text across multiple files, Documentation for etags, Using regular expressions, Common requests
@section How do I perform a replace operation across more than one file?
@cindex Replacing strings across files
@cindex Multiple files, replacing across
@cindex Files, replacing strings across multiple

The ``tags'' feature of Emacs includes the command
@code{tags-query-replace} which performs a query-replace across all the
files mentioned in the @file{TAGS} file.  @inforef{Tags Search, Tags Search,
emacs}.

As of Emacs 19.29, Dired mode (@kbd{M-x dired @key{RET}}, or @kbd{C-x
d}) supports the command @code{dired-do-query-replace}, which allows
users to replace regular expressions in multiple files.

@node Documentation for etags, Disabling backups, Replacing text across multiple files, Common requests
@section Where is the documentation for @code{etags}?
@cindex Documentation for @code{etags}
@cindex @code{etags}, documentation for

The @code{etags} man page should be in the same place as the
@code{emacs} man page.

Quick command-line switch descriptions are also available.  For example,
@samp{etags -H}.

@node Disabling backups, Disabling auto-save-mode, Documentation for etags, Common requests
@section How do I disable backup files?
@cindex Backups, disabling
@cindex Disabling backups

You probably don't want to do this, since backups are useful, especially
when something goes wrong.

To avoid seeing backup files (and other "uninteresting" files) in Dired,
load @code{dired-x} by adding the following to your @file{.emacs} file:

@lisp
(add-hook 'dired-load-hook
          (lambda ()
           (load "dired-x")))
@end lisp

With @code{dired-x} loaded, @kbd{M-o} toggles omitting in each dired buffer.
You can make omitting the default for new dired buffers by putting the
following in your @file{.emacs}:

@lisp
(add-hook 'dired-mode-hook 'dired-omit-toggle)
@end lisp

If you're tired of seeing backup files whenever you do an @samp{ls} at
the Unix shell, try GNU @code{ls} with the @samp{-B} option.  GNU
@code{ls} is part of the GNU Fileutils package, available from
@samp{ftp.gnu.org} and its mirrors (@pxref{Current GNU distributions}).

To disable or change the way backups are made, @inforef{Backup Names, ,
emacs}.

@cindex Backup files in a single directory
Beginning with Emacs 21.1, you can control where Emacs puts backup files
by customizing the variable @code{backup-directory-alist}.  This
variable's value specifies that files whose names match specific patters
should have their backups put in certain directories.  A typical use is
to add the element @code{("." . @var{dir})} to force Emacs to put
@strong{all} backup files in the directory @file{dir}.

@node Disabling auto-save-mode, Going to a line by number, Disabling backups, Common requests
@section How do I disable @code{auto-save-mode}?
@cindex Disabling @code{auto-save-mode}
@cindex Auto-saving
@cindex Saving at frequent intervals

You probably don't want to do this, since auto-saving is useful,
especially when Emacs or your computer crashes while you are editing a
document.

Instead, you might want to change the variable
@code{auto-save-interval}, which specifies how many keystrokes Emacs
waits before auto-saving.  Increasing this value forces Emacs to wait
longer between auto-saves, which might annoy you less.

You might also want to look into Sebastian Kremer's @code{auto-save}
package (@pxref{Packages that do not come with Emacs}).  This
package also allows you to place all auto-save files in one directory,
such as @file{/tmp}.

To disable or change how @code{auto-save-mode} works, @inforef{Auto
Save, , emacs}.

@node Going to a line by number, Modifying pull-down menus, Disabling auto-save-mode, Common requests
@section How can I go to a certain line given its number?
@cindex Going to a line by number
@cindex Compilation error messages
@cindex Recompilation

Are you sure you indeed need to go to a line by its number?  Perhaps all
you want is to display a line in your source file for which a compiler
printed an error message?  If so, compiling from within Emacs using the
@kbd{M-x compile} and @kbd{M-x recompile} commands is a much more
effective way of doing that.  Emacs automatically intercepts the compile
error messages, inserts them into a special buffer called
@code{*compilation*}, and lets you visit the locus of each message in
the source.  Type @kbd{C-x `} to step through the offending lines one by
one.  Click @kbd{Mouse-2} or press @key{RET} on a message text in the
@code{*compilation*} buffer to go to the line whose number is mentioned
in that message.

But if you indeed need to go to a certain text line, type @kbd{M-x
goto-line @key{RET}}.  Emacs will prompt you for the number of the line
and go to that line.

You can do this faster by invoking @code{goto-line} with a numeric
argument that is the line's number.  For example, @kbd{C-u 286 M-x
goto-line @key{RET}} will jump to line number 286 in the current
buffer.

If you need to use this command frequently, you might consider binding
it to a key.  The following snippet, if added to your @file{~/.emacs}
file, will bind the sequence @kbd{C-x g} to @code{goto-line}:

@lisp
 (global-set-key "\C-xg" 'goto-line)
@end lisp


@node Modifying pull-down menus, Deleting menus and menu options, Going to a line by number, Common requests
@section How can I create or modify new pull-down menu options?
@cindex Pull-down menus, creating or modifying
@cindex Menus, creating or modifying
@cindex Creating new menu options
@cindex Modifying pull-down menus
@cindex Menus and keymaps
@cindex Keymaps and menus

Each menu title (e.g., @samp{File}, @samp{Edit}, @samp{Buffers})
represents a local or global keymap.  Selecting a menu title with the
mouse displays that keymap's non-nil contents in the form of a menu.

So to add a menu option to an existing menu, all you have to do is add a
new definition to the appropriate keymap.  Adding a @samp{Forward Word}
item to the @samp{Edit} menu thus requires the following Lisp code:

@lisp
(define-key global-map
  [menu-bar edit forward]
  '("Forward word" . forward-word))
@end lisp

@noindent
The first line adds the entry to the global keymap, which includes
global menu bar entries.  Replacing the reference to @code{global-map}
with a local keymap would add this menu option only within a particular
mode.

The second line describes the path from the menu-bar to the new entry.
Placing this menu entry underneath the @samp{File} menu would mean
changing the word @code{edit} in the second line to @code{file}.

The third line is a cons cell whose first element is the title that will
be displayed, and whose second element is the function that will be
called when that menu option is invoked.

To add a new menu, rather than a new option to an existing menu, we must
define an entirely new keymap:

@lisp
(define-key global-map [menu-bar words]
  (cons "Words" (make-sparse-keymap "Words")))
@end lisp

The above code creates a new sparse keymap, gives it the name
@samp{Words}, and attaches it to the global menu bar.  Adding the
@samp{Forward Word} item to this new menu would thus require the
following code:

@lisp
(define-key global-map
  [menu-bar words forward]
  '("Forward word" . forward-word))
@end lisp

@noindent
Note that because of the way keymaps work, menu options are displayed
with the more recently defined items at the top.  Thus if you were to
define menu options @samp{foo}, @samp{bar}, and @samp{baz} (in that
order), the menu option @samp{baz} would appear at the top, and
@samp{foo} would be at the bottom.

One way to avoid this problem is to use the function @code{define-key-after},
which works the same as @code{define-key}, but lets you modify where items
appear.  The following Lisp code would insert the @samp{Forward Word}
item in the @samp{Edit} menu immediately following the @samp{Undo} item:

@lisp
(define-key-after
  (lookup-key global-map [menu-bar edit])
  [forward]
  '("Forward word" . forward-word)
  'undo)
@end lisp

Note how the second and third arguments to @code{define-key-after} are
different from those of @code{define-key}, and that we have added a new
(final) argument, the function after which our new key should be
defined.

To move a menu option from one position to another, simply evaluate
@code{define-key-after} with the appropriate final argument.

More detailed information---and more examples of how to create and
modify menu options---are in the @cite{Emacs Lisp Reference Manual}, under
``Menu Keymaps''.  (@xref{Emacs Lisp documentation}, for information on
this manual.)

@node Deleting menus and menu options, Turning on syntax highlighting, Modifying pull-down menus, Common requests
@section How do I delete menus and menu options?
@cindex Deleting menus and menu options
@cindex Menus, deleting

The simplest way to remove a menu is to set its keymap to @samp{nil}.
For example, to delete the @samp{Words} menu (@pxref{Modifying pull-down
menus}), use:

@lisp
(define-key global-map [menu-bar words] nil)
@end lisp

Similarly, removing a menu option requires redefining a keymap entry to
@code{nil}.  For example, to delete the @samp{Forward word} menu option
from the @samp{Edit} menu (we added it in @ref{Modifying pull-down
menus}), use:

@lisp
(define-key global-map [menu-bar edit forward] nil)
@end lisp

@node Turning on syntax highlighting, Scrolling only one line, Deleting menus and menu options, Common requests
@section How do I turn on syntax highlighting?
@cindex Syntax highlighting
@cindex @code{font-lock-mode}
@cindex Highlighting based on syntax
@cindex Colorizing text
@cindex FAQ, @code{font-lock-mode}

@code{font-lock-mode} is the standard way to have Emacs perform syntax
highlighting in the current buffer.  With @code{font-lock-mode} turned
on, different types of text will appear in different colors.  For
instance, if you turn on @code{font-lock-mode} in a programming mode,
variables will appear in one face, keywords in a second, and comments in
a third.

@cindex hilit19 is deprecated
Earlier versions of Emacs supported hilit19, a similar package.  Use of
hilit19 is now considered non-standard, although @file{hilit19.el} comes
with the stock Emacs distribution.  It is no longer maintained.

To turn @code{font-lock-mode} on within an existing buffer, use @kbd{M-x
font-lock-mode @key{RET}}.

To automatically invoke @code{font-lock-mode} when a particular major
mode is invoked, set the major mode's hook.  For example, to fontify all
@code{c-mode} buffers, add the following to your @file{.emacs} file:

@lisp
(add-hook 'c-mode-hook 'turn-on-font-lock)
@end lisp

To automatically invoke @code{font-lock-mode} for all major modes, you
can turn on @code{global-font-lock-mode} by including the following line
in your @file{.emacs} file:

@lisp
(global-font-lock-mode 1)
@end lisp

@noindent
This instructs Emacs to turn on font-lock mode in those buffers for
which a font-lock mode definition has been provided (in the variable
@code{font-lock-global-modes}).  If you edit a file in
@code{pie-ala-mode}, and no font-lock definitions have been provided for
@code{pie-ala} files, then the above setting will have no effect on that
particular buffer.

Highlighting a buffer with @code{font-lock-mode} can take quite a while,
and cause an annoying delay in display, so several features exist to
work around this.

@cindex Just-In-Time syntax highlighting
In Emacs 21 and later, turning on @code{font-lock-mode} automatically
activates the new @dfn{Just-In-Time fontification} provided by
@code{jit-lock-mode}.  @code{jit-lock-mode} defers the fontification of
portions of buffer until you actually need to see them, and can also
fontify while Emacs is idle.  This makes display of the visible portion
of a buffer almost instantaneous.  For details about customizing
@code{jit-lock-mode}, type @kbd{C-h f jit-lock-mode @key{RET}}.

@cindex Levels of syntax highlighting
@cindex Decoration level, in @code{font-lock-mode}
In versions of Emacs before 21, different levels of decoration are
available, from slight to gaudy.  More decoration means you need to wait
more time for a buffer to be fontified (or a faster machine).  To
control how decorated your buffers should become, set the value of
@code{font-lock-maximum-decoration} in your @file{.emacs} file, with a
@code{nil} value indicating default (usually minimum) decoration, and a
@code{t} value indicating the maximum decoration.  For the gaudiest
possible look, then, include the line

@lisp
(setq font-lock-maximum-decoration t)
@end lisp

@noindent
in your @file{.emacs} file.  You can also set this variable such that
different modes are highlighted in a different ways; for more
information, see the documentation for
@code{font-lock-maximum-decoration} with @kbd{C-h v} (or @kbd{M-x
describe-variable @key{RET}}).

@cindex Lazy font-lock
You might also want to investigate @code{fast-lock-mode} and
@code{lazy-lock-mode}, versions of @code{font-lock-mode} that speed up
highlighting.  These are the alternatives for @code{jit-lock-mode} in
versions of Emacs before 21.1.  The advantage of @code{lazy-lock-mode}
is that it only fontifies buffers when certain conditions are met, such
as after a certain amount of idle time, or after you have finished
scrolling through text.  See the documentation for @code{lazy-lock-mode}
by typing @kbd{C-h f @code{lazy-lock-mode}} (@kbd{M-x describe-function
@key{RET} lazy-lock-mode @key{RET}}).

Also see the documentation for the function @code{font-lock-mode},
available by typing @kbd{C-h f font-lock-mode} (@kbd{M-x
describe-function @key{RET} font-lock-mode @key{RET}}).

For more information on font-lock mode, take a look at the
@code{font-lock-mode} FAQ, maintained by
@email{jari.aalto@@ntc.nokia.com, Jari Aalto} at

@uref{ftp://cs.uta.fi/pub/ssjaaa/ema-font.gui}

To print buffers with the faces (i.e., colors and fonts) intact, use
@kbd{M-x ps-print-buffer-with-faces} or @kbd{M-x
ps-print-region-with-faces}.  You will need a way to send text to a
PostScript printer, or a PostScript interpreter such as Ghostscript;
consult the documentation of the variables @code{ps-printer-name},
@code{ps-lpr-command}, and @code{ps-lpr-switches} for more details.

@node Scrolling only one line, Replacing highlighted text, Turning on syntax highlighting, Common requests
@section How can I force Emacs to scroll only one line when I move past the bottom of the screen?
@cindex Scrolling only one line
@cindex Reducing the increment when scrolling

Place the following Lisp form in your @file{.emacs} file:

@lisp
(setq scroll-step 1)
@end lisp

@inforef{Scrolling, Scrolling, emacs}.

@node Replacing highlighted text, Editing MS-DOS files, Scrolling only one line, Common requests
@section How can I replace highlighted text with what I type?
@cindex @code{delete-selection-mode}
@cindex Replacing highlighted text
@cindex Highlighting and replacing text

Use @code{delete-selection-mode}, which you can start automatically by
placing the following Lisp form in your @file{.emacs} file:

@lisp
(delete-selection-mode t)
@end lisp

According to the documentation string for @code{delete-selection-mode}
(which you can read using @kbd{M-x describe-function @key{RET}
delete-selection-mode @key{RET}}):

@quotation
When ON, typed text replaces the selection if the selection is active.
When OFF, typed text is just inserted at point.
@end quotation

This mode also allows you to delete (not kill) the highlighted region by
pressing @key{DEL}.

@node Editing MS-DOS files, Filling paragraphs with a single space, Replacing highlighted text, Common requests
@section How can I edit MS-DOS files using Emacs?
@cindex Editing MS-DOS files
@cindex MS-DOS files, editing
@cindex Microsoft files, editing
@cindex Windows files, editing

As of Emacs 20, detection and handling of MS-DOS (and Windows) files is
performed transparently.  You can open MS-DOS files on a Unix system,
edit it, and save it without having to worry about the file format.

When editing an MS-DOS style file, the mode line will indicate that it
is a DOS file.  On Unix and GNU/Linux systems, and also on a Macintosh,
the string @samp{(DOS)} will appear near the left edge of the mode line;
on DOS and Windows, where the DOS end-of-line (EOL) format is the
default, a backslash (@samp{\}) will appear in the mode line.

If you are running a version of Emacs before 20.1, get @code{crypt++}
(@pxref{Packages that do not come with Emacs}).  Among other things, 
@code{crypt++} transparently modifies MS-DOS files as they are loaded
and saved, allowing you to ignore the different conventions that Unix
and MS-DOS have for delineating the end of a line.

@node Filling paragraphs with a single space,  Escape sequences in shell output, Editing MS-DOS files, Common requests
@section How can I tell Emacs to fill paragraphs with a single space after each period?
@cindex One space following periods
@cindex Single space following periods
@cindex Periods, one space following

@email{ulm@@vsnhd1.cern.ch, Ulrich Mueller} suggests adding the
following two lines to your @file{.emacs} file:

@lisp
(setq sentence-end "[.?!][]\"')@}]*\\($\\|[ \t]\\)[ \t\n]*")
(setq sentence-end-double-space nil)
@end lisp

@node Escape sequences in shell output, , Filling paragraphs with a single space, Common requests
@section Why these strange escape sequences from @code{ls} from the Shell mode?
@cindex Escape sequences in @code{ls} output
@cindex @code{ls} in Shell mode

This happens because @code{ls} is aliased to @samp{ls --color} in your
shell init file.  You have two alternatives to solve this:

@itemize @bullet
@item
Make the alias conditioned on the @code{EMACS} variable in the
environment.  When Emacs runs a subsidiary shell, it exports the
@code{EMACS} variable with the value @code{t} to that shell.  You can
unalias @code{ls} when that happens, thus limiting the alias to your
interactive sessions.

@item
Install the @code{ansi-color} package (bundled with Emacs 21.1 and
later), which converts these ANSI escape sequences into colors.
@end itemize

@c ------------------------------------------------------------
@node    Bugs and problems, Compiling and installing Emacs, Common requests, Top
@chapter Bugs and problems
@cindex Bugs and problems

The Emacs manual lists some common kinds of trouble users could get
into, see @ref{Lossage, , Dealing with Emacs Trouble, emacs, The GNU
Emacs Manual}, so you might look there if the problem you encounter
isn't described in this chapter.  If you decide you've discovered a bug,
see @ref{Bugs, , Reporting Bugs, emacs, The GNU Emacs Manual}, for
instructions how to do that.

The file @file{etc/PROBLEMS} in the Emacs distribution lists various
known problems with building and using Emacs on specific platforms;
type @kbd{C-h P} to read it.

@menu
* Problems with very large files::
* ^M in the shell buffer::
* Shell process exits abnormally::
* Problems with Shell Mode on MS-Windows::
* Termcap/Terminfo entries for Emacs::
* Spontaneous entry into isearch-mode::
* Problems talking to certain hosts::
* Errors with init files::
* Emacs ignores X resources::
* Emacs ignores frame parameters::
* Emacs takes a long time to visit files::
* Editing files with $ in the name::
* Shell mode loses the current directory::
* Security risks with Emacs::
* Dired claims that no file is on this line::
@end menu

@node Problems with very large files, ^M in the shell buffer, Bugs and problems, Bugs and problems
@section Does Emacs have problems with files larger than 8 megabytes?
@cindex Very large files, opening
@cindex Large files, opening
@cindex Opening very large files
@cindex Maximum file size
@cindex Files, maximum size

Old versions (i.e., anything before 19.29) of Emacs had problems editing
files larger than 8 megabytes.  As of version 19.29, the maximum buffer
size is at least 2^27-1, or 134,217,727 bytes, or 132 MBytes.  Emacs 20
can be compiled on some 64-bit systems in a way that enlarges the buffer
size up to 576,460,752,303,423,487 bytes, or 549,755,813 GBytes.

If you are using a version of Emacs older than 19.29 and cannot upgrade,
you will have to recompile. @email{lnz@@lucid.com, Leonard N. Zubkoff}
suggests putting the following two lines in @file{src/config.h} before
compiling Emacs to allow for 26-bit integers and pointers (and thus file
sizes of up to 33,554,431 bytes):

@example
#define VALBITS 26
#define GCTYPEBITS 5
@end example

@noindent
This method may result in "ILLEGAL DATATYPE" and other random errors on
some machines.

@email{daveg@@csvax.cs.caltech.edu, David Gillespie} explains how this
problems crops up; while his numbers are true only for pre-19.29
versions of Emacs, the theory remains the same with current versions.

@quotation
Emacs is largely written in a dialect of Lisp; Lisp is a freely-typed
language in the sense that you can put any value of any type into any
variable, or return it from a function, and so on.  So each value
must carry a @dfn{tag} along with it identifying what kind of thing it
is, e.g., integer, pointer to a list, pointer to an editing buffer, and
so on.  Emacs uses standard 32-bit integers for data objects, taking the
top 8 bits for the tag and the bottom 24 bits for the value.  So
integers (and pointers) are somewhat restricted compared to true C
integers and pointers.
@end quotation

@node ^M in the shell buffer, Shell process exits abnormally, Problems with very large files, Bugs and problems
@section How do I get rid of @samp{^M} or echoed commands in my shell buffer?
@cindex Shell buffer, echoed commands and @samp{^M} in
@cindex Echoed commands in @code{shell-mode}

Try typing @kbd{M-x shell-strip-ctrl-m @key{RET}} while in @code{shell-mode} to
make them go away.  If that doesn't work, you have several options:

For @code{tcsh}, put this in your @file{.cshrc} (or @file{.tcshrc})
file:

@example
if ($?EMACS) then
    if ("$EMACS" == t) then
        if ($?tcsh) unset edit
        stty nl
    endif
endif
@end example

Or put this in your @file{.emacs_tcsh} file:

@example
unset edit
stty nl
@end example

Alternatively, use @code{csh} in your shell buffers instead of
@code{tcsh}.  One way is:

@lisp
(setq explicit-shell-file-name "/bin/csh")
@end lisp

@noindent
and another is to do this in your @file{.cshrc} (or @file{.tcshrc})
file:

@example
setenv ESHELL /bin/csh
@end example

@noindent
(You must start Emacs over again with the environment variable properly
set for this to take effect.)

You can also set the @code{ESHELL} environment variable in Emacs Lisp
with the following Lisp form,

@lisp
(setenv "ESHELL" "/bin/csh")
@end lisp

The above solutions try to prevent the shell from producing the
@samp{^M} characters in the first place.  If this is not possible
(e.g., if you use a Windows shell), you can get Emacs to remove these
characters from the buffer by adding this to your @file{.emacs} init
file:

@smalllisp
(add-hook 'comint-output-filter-functions 'shell-strip-ctrl-m)
@end smalllisp

On a related note: If your shell is echoing your input line in the shell
buffer, you might want to try the following command in your shell
start-up file:

@example
stty -icrnl -onlcr -echo susp ^Z
@end example

@node Shell process exits abnormally, Problems with Shell Mode on MS-Windows, ^M in the shell buffer, Bugs and problems
@section Why do I get "Process shell exited abnormally with code 1"?
@cindex Abnormal exits from @code{shell-mode}
@cindex @code{shell-mode} exits
@cindex Process shell exited

The most likely reason for this message is that the @samp{env} program
is not properly installed.  Compile this program for your architecture,
and install it with @samp{a+x} permission in the architecture-dependent
Emacs program directory.  (You can find what this directory is at your
site by inspecting the value of the variable @code{exec-directory} by
typing @kbd{C-h v exec-directory @key{RET}}.)

You should also check for other programs named @samp{env} in your path
(e.g., SunOS has a program named @file{/usr/bin/env}).  We don't
understand why this can cause a failure and don't know a general
solution for working around the problem in this case.

The @samp{make clean} command will remove @samp{env} and other vital
programs, so be careful when using it.

It has been reported that this sometimes happened when Emacs was started
as an X client from an xterm window (i.e., had a controlling tty) but the
xterm was later terminated.

See also @samp{PROBLEMS} (in the @file{etc} subdirectory of the
top-level directory when you unpack the Emacs source) for other
possible causes of this message.

@node Problems with Shell Mode on MS-Windows, Termcap/Terminfo entries for Emacs, Shell process exits abnormally, Bugs and problems
@section Why do I get an error message when I try to run @kbd{M-x shell}?

@cindex Shell Mode, and MS-Windows
@cindex @code{explicit-shell-file-name}
On MS-Windows, this might happen because Emacs tries to look for the
shell in a wrong place.  The default file name @file{/bin/sh} is
usually incorrect for non-Unix systems.  If you know where your shell
executable is, set the variable @code{explicit-shell-file-name} in
your @file{.emacs} file to point to its full file name, like this:

@lisp
(setq explicit-shell-file-name "d:/shells/bash.exe")
@end lisp

If you don't know what shell does Emacs use, try the @kbd{M-!}
command; if that works, put the following line into your
@file{.emacs}:

@lisp
(setq explicit-shell-file-name shell-file-name)
@end lisp

@cindex Antivirus programs, and Shell Mode
Some people have trouble with Shell Mode because of intrusive
antivirus software; disabling the resident antivirus program solves
the problems in those cases.

@node Termcap/Terminfo entries for Emacs, Spontaneous entry into isearch-mode, Problems with Shell Mode on MS-Windows, Bugs and problems
@section Where is the termcap/terminfo entry for terminal type "emacs"?
@cindex Termcap
@cindex Terminfo
@cindex Emacs entries for termcap/terminfo

The termcap entry for terminal type @samp{emacs} is ordinarily put in
the @samp{TERMCAP} environment variable of subshells.  It may help in
certain situations (e.g., using rlogin from shell buffer) to add an
entry for @samp{emacs} to the system-wide termcap file.  Here is a
correct termcap entry for @samp{emacs}:

@example
emacs:tc=unknown:
@end example

To make a terminfo entry for @samp{emacs}, use @code{tic} or
@code{captoinfo}.  You need to generate
@file{/usr/lib/terminfo/e/emacs}.  It may work to simply copy
@file{/usr/lib/terminfo/d/dumb} to @file{/usr/lib/terminfo/e/emacs}.

Having a termcap/terminfo entry will not enable the use of full screen
programs in shell buffers.  Use @kbd{M-x terminal-emulator} for that
instead.

A workaround to the problem of missing termcap/terminfo entries is to
change terminal type @samp{emacs} to type @samp{dumb} or @samp{unknown}
in your shell start up file.  @code{csh} users could put this in their
@file{.cshrc} files:

@example
if ("$term" == emacs) set term=dumb
@end example

@node Spontaneous entry into isearch-mode, Problems talking to certain hosts, Termcap/Terminfo entries for Emacs, Bugs and problems
@section Why does Emacs spontaneously start displaying "I-search:" and beeping?
@cindex Spontaneous entry into isearch-mode
@cindex isearch-mode, spontaneous entry into
@cindex Beeping without obvious reason

Your terminal (or something between your terminal and the computer) is
sending @kbd{C-s} and @kbd{C-q} for flow control, and Emacs is receiving
these characters and interpreting them as commands.  (The @kbd{C-s}
character normally invokes the @code{isearch-forward} command.)  For
possible solutions, see @ref{Handling C-s and C-q with flow control}.

@node Problems talking to certain hosts, Errors with init files, Spontaneous entry into isearch-mode, Bugs and problems
@section Why can't Emacs talk to certain hosts (or certain hostnames)?
@cindex Hosts, Emacs cannot talk to
@cindex @code{gethostbyname}, problematic version

The problem may be that Emacs is linked with a wimpier version of
@code{gethostbyname} than the rest of the programs on the machine.  This
is often manifested as a message on startup of ``X server not responding.
Check your @samp{DISPLAY} environment variable.'' or a message of
``Unknown host'' from @code{open-network-stream}.

On a Sun, this may be because Emacs had to be linked with the static C
library.  The version of @code{gethostbyname} in the static C library
may only look in @file{/etc/hosts} and the NIS (YP) maps, while the
version in the dynamic C library may be smart enough to check DNS in
addition to or instead of NIS.  On a Motorola Delta running System V
R3.6, the version of @code{gethostbyname} in the standard library works,
but the one that works with NIS doesn't (the one you get with -linet).
Other operating systems have similar problems.

Try these options:

@itemize @bullet

@item
Explicitly add the host you want to communicate with to @file{/etc/hosts}.

@item
Relink Emacs with this line in @file{src/config.h}:

@example
#define LIBS_SYSTEM -lresolv
@end example

@item
Replace @code{gethostbyname} and friends in @file{libc.a} with more
useful versions such as the ones in @file{libresolv.a}.  Then relink
Emacs.

@item
If you are actually running NIS, make sure that @code{ypbind} is
properly told to do DNS lookups with the correct command line switch.

@end itemize

@node Errors with init files, Emacs ignores X resources, Problems talking to certain hosts, Bugs and problems
@section Why does Emacs say "Error in init file"?
@cindex Error in @file{.emacs}
@cindex Error in init file
@cindex Init file, errors in
@cindex @file{.emacs} file, errors in
@cindex Debugging @file{.emacs} file

An error occurred while loading either your @file{.emacs} file or the
system-wide file @file{lisp/default.el}.  Emacs 21.1 and later pops the
@file{*Messages*} buffer, and puts there some additional information
about the error, to provide some hints for debugging.

For information on how to debug your @file{.emacs} file, see
@ref{Debugging a customization file}.

It may be the case that you need to load some package first, or use a
hook that will be evaluated after the package is loaded.  A common case
of this is explained in @ref{Terminal setup code works after Emacs has
begun}.

@node Emacs ignores X resources, Emacs ignores frame parameters, Errors with init files, Bugs and problems
@section Why does Emacs ignore my X resources (my .Xdefaults file)?
@cindex X resources being ignored
@cindex Ignored X resources
@cindex @file{.Xdefaults}

As of version 19, Emacs searches for X resources in the files specified
by the following environment variables:

@itemize @bullet

@item @code{XFILESEARCHPATH}
@item @code{XUSERFILESEARCHPATH}
@item @code{XAPPLRESDIR}

@end itemize

This emulates the functionality provided by programs written using the
Xt toolkit.

@code{XFILESEARCHPATH} and @code{XUSERFILESEARCHPATH} should be a list
of file names separated by colons.  @code{XAPPLRESDIR} should be a list
of directory names separated by colons.

Emacs searches for X resources:

@enumerate

@item
specified on the command line, with the @samp{-xrm RESOURCESTRING} option,

@item
then in the value of the @samp{XENVIRONMENT} environment variable,

@itemize @minus

@item
or if that is unset, in the file named
@file{~/.Xdefaults-@var{hostname}} if it exists (where @var{hostname} is
the name of the machine Emacs is running on),

@end itemize

@item
then in the screen-specific and server-wide resource properties provided
by the server,

@itemize @minus

@item
or if those properties are unset, in the file named @file{~/.Xdefaults}
if it exists,

@end itemize

@item
then in the files listed in @samp{XUSERFILESEARCHPATH},

@itemize @minus

@item
or in files named @file{@var{lang}/Emacs} in directories listed in
@samp{XAPPLRESDIR} (where @var{lang} is the value of the @code{LANG}
environment variable), if the @samp{LANG} environment variable is set,
@item
or in files named Emacs in the directories listed in @samp{XAPPLRESDIR}
@item
or in @file{~/@var{lang}/Emacs} (if the @code{LANG} environment variable
is set),
@item
or in @file{~/Emacs},

@end itemize

@item
then in the files listed in  @code{XFILESEARCHPATH}.

@end enumerate

@node Emacs ignores frame parameters, Emacs takes a long time to visit files, Emacs ignores X resources, Bugs and problems
@section Why don't my customizations of the frame parameters work?
@cindex Frame parameters

This probably happens because you have set the frame parameters in the
variable @code{initial-frame-alist}.  That variable holds parameters
used only for the first frame created when Emacs starts.  To customize
the parameters of all frames, change the variable
@code{default-frame-alist} instead.

These two variables exist because many users customize the initial frame
in a special way.  For example, you could determine the position and
size of the initial frame, but would like to control the geometry of the
other frames by individually positioning each one of them.


@node Emacs takes a long time to visit files, Editing files with $ in the name, Emacs ignores frame parameters, Bugs and problems
@section Why does Emacs take 20 seconds to visit a file?
@cindex Visiting files takes a long time
@cindex Delay when visiting files
@cindex Files, take a long time to visit

Old versions of Emacs (i.e., versions before Emacs 20.x) often
encountered this when the master lock file, @file{!!!SuperLock!!!}, has
been left in the lock directory somehow.  Delete it.

@email{meuer@@geom.umn.edu, Mark Meuer} says that NeXT NFS has a bug
where an exclusive create succeeds but returns an error status.  This
can cause the same problem.  Since Emacs's file locking doesn't work
over NFS anyway, the best solution is to recompile Emacs with
@code{CLASH_DETECTION} undefined.

@node Editing files with $ in the name, Shell mode loses the current directory, Emacs takes a long time to visit files, Bugs and problems
@section How do I edit a file with a @samp{$} in its name?
@cindex Editing files with @samp{$} in the name
@cindex @samp{$} in file names
@cindex File names containing @samp{$}, editing

When entering a file name in the minibuffer, Emacs will attempt to expand
a @samp{$} followed by a word as an environment variable.  To suppress
this behavior, type @kbd{$$} instead.

@node Shell mode loses the current directory, Security risks with Emacs, Editing files with $ in the name, Bugs and problems
@section Why does shell mode lose track of the shell's current directory?
@cindex Current directory and @code{shell-mode}
@cindex @code{shell-mode} and current directory
@cindex Directory, current in @code{shell-mode}

Emacs has no way of knowing when the shell actually changes its
directory.  This is an intrinsic limitation of Unix.  So it tries to
guess by recognizing @samp{cd} commands.  If you type @kbd{cd} followed
by a directory name with a variable reference (@kbd{cd $HOME/bin}) or
with a shell metacharacter (@kbd{cd ../lib*}), Emacs will fail to
correctly guess the shell's new current directory.  A huge variety of
fixes and enhancements to shell mode for this problem have been written
to handle this problem (@pxref{Finding a package with particular
functionality}).

You can tell Emacs the shell's current directory with the command
@kbd{M-x dirs}.

@node Security risks with Emacs, Dired claims that no file is on this line, Shell mode loses the current directory, Bugs and problems
@section Are there any security risks in Emacs?
@cindex Security with Emacs
@cindex @samp{movemail} and security
@cindex @code{file-local-variable} and security
@cindex Synthetic X events and security
@cindex X events and security

@itemize @bullet

@item
The @file{movemail} incident.  (No, this is not a risk.)

In his book @cite{The Cuckoo's Egg}, Cliff Stoll describes this in
chapter 4.  The site at LBL had installed the @file{/etc/movemail}
program setuid root.  (As of version 19, @file{movemail} is in your
architecture-specific directory; type @kbd{C-h v exec-directory
@key{RET}} to see what it is.)  Since @code{movemail} had not been
designed for this situation, a security hole was created and users could
get root privileges.

@code{movemail} has since been changed so that this security hole will
not exist, even if it is installed setuid root.  However,
@code{movemail} no longer needs to be installed setuid root, which
should eliminate this particular risk.

We have heard unverified reports that the 1988 Internet worm took
advantage of this configuration problem.

@item
The @code{file-local-variable} feature.  (Yes, a risk, but easy to
change.)

There is an Emacs feature that allows the setting of local values for
variables when editing a file by including specially formatted text near
the end of the file.  This feature also includes the ability to have
arbitrary Emacs Lisp code evaluated when the file is visited.
Obviously, there is a potential for Trojan horses to exploit this
feature.

Emacs 18 allowed this feature by default; users could disable it by
setting the variable @code{inhibit-local-variables} to a non-nil value.

As of Emacs 19, Emacs has a list of local variables that create a
security risk.  If a file tries to set one of them, it asks the user to
confirm whether the variables should be set.  You can also tell Emacs
whether to allow the evaluation of Emacs Lisp code found at the bottom
of files by setting the variable @code{enable-local-eval}.

For more information, @inforef{File Variables, File Variables, emacs}.

@item
Synthetic X events.  (Yes, a risk; use @samp{MIT-MAGIC-COOKIE-1} or
better.)

Emacs accepts synthetic X events generated by the @code{SendEvent}
request as though they were regular events.  As a result, if you are
using the trivial host-based authentication, other users who can open X
connections to your X workstation can make your Emacs process do
anything, including run other processes with your privileges.

The only fix for this is to prevent other users from being able to open
X connections.  The standard way to prevent this is to use a real
authentication mechanism, such as @samp{MIT-MAGIC-COOKIE-1}.  If using
the @code{xauth} program has any effect, then you are probably using
@samp{MIT-MAGIC-COOKIE-1}.  Your site may be using a superior
authentication method; ask your system administrator.

If real authentication is not a possibility, you may be satisfied by
just allowing hosts access for brief intervals while you start your X
programs, then removing the access.  This reduces the risk somewhat by
narrowing the time window when hostile users would have access, but
@emph{does not eliminate the risk}.

On most computers running Unix and X, you enable and disable
access using the @code{xhost} command.  To allow all hosts access to
your X server, use

@example
xhost +
@end example

@noindent
at the shell prompt, which (on an HP machine, at least) produces the
following message:

@example
access control disabled, clients can connect from any host
@end example

To deny all hosts access to your X server (except those explicitly
allowed by name), use

@example
xhost -
@end example

On the test HP computer, this command generated the following message:

@example
access control enabled, only authorized clients can connect
@end example

@end itemize

@node Dired claims that no file is on this line,  , Security risks with Emacs, Bugs and problems
@section Dired says, "no file on this line" when I try to do something.
@cindex Dired does not see a file

@c FIXME: I think this is fixed in Emacs 21, but I didn't have time to
@c check.
Chances are you're using a localized version of Unix that doesn't use US
date format in dired listings.  You can check this by looking at dired
listings or by typing @kbd{ls -l} to a shell and looking at the dates that
come out.

Dired uses a regular expression to find the beginning of a file name.
In a long Unix-style directory listing (@samp{ls -l}), the file name
starts after the date.  The regexp has thus been written to look for the
date, the format of which can vary on non-US systems.

There are two approaches to solving this.  The first one involves
setting things up so that @samp{ls -l} outputs US date format.  This can
be done by setting the locale.  See your OS manual for more information.

The second approach involves changing the regular expression used by
dired, @code{dired-move-to-filename-regexp}.

@c ------------------------------------------------------------
@node Compiling and installing Emacs, Finding Emacs and related packages, Bugs and problems, Top
@chapter    Compiling and installing Emacs
@cindex    Compiling and installing Emacs

@menu
* Installing Emacs::
* Updating Emacs::
* Problems building Emacs::
* Linking with -lX11 fails::
@end menu

@node Installing Emacs, Updating Emacs, Compiling and installing Emacs, Compiling and installing Emacs
@section How do I install Emacs?
@cindex Installing Emacs
@cindex Unix systems, installing Emacs on
@cindex Downloading and installing Emacs
@cindex Retrieving and installing Emacs
@cindex Building Emacs from source
@cindex Source code, building Emacs from
@cindex Unpacking and installing Emacs

This answer is meant for users of Unix and Unix-like systems.  Users of
other operating systems should see the series of questions beginning
with @ref{Emacs for MS-DOS}, which describe where to get non-Unix source
and binaries, and how to install Emacs on those systems.

For Unix and Unix-like systems, the easiest way is often to compile it
from scratch.  You will need:

@itemize @bullet

@item
Emacs sources.  @xref{Current GNU distributions}, for a list of ftp sites
that make them available.  On @file{ftp.gnu.org}, the main GNU
distribution site, sources are available as

@uref{ftp://ftp.gnu.org/pub/gnu/emacs/emacs-@value{VER}.tar.gz}

The above will obviously change as new versions of Emacs come out.  For
instance, when Emacs 21.42 is released, it will most probably be
available as

@uref{ftp://ftp.gnu.org/pub/gnu/emacs/emacs-21.42.tar.gz}

Again, you should use one of the GNU mirror sites (see @ref{Current GNU
distributions}, and adjust the URL accordingly) so as to reduce load on
@file{ftp.gnu.org}.

@item
@code{gzip}, the GNU compression utility.  You can get @code{gzip} via
anonymous ftp at mirrors of @file{ftp.gnu.org} sites; it should compile
and install without much trouble on most systems.  Once you have
retrieved the Emacs sources, you will probably be able to uncompress
them with the command

@example
gunzip --verbose emacs-@value{VER}.tar.gz
@end example

@noindent
changing the Emacs version (@value{VER}), as necessary.  Once
@code{gunzip} has finished doing its job, a file by the name of
@file{emacs-@value{VER}.tar} should be in your build directory.

@item
@code{tar}, the @dfn{tape archiving} program, which moves multiple files
into and out of archive files, or @dfn{tarfiles}.  All of the files
comprising the Emacs source come in a single tarfile, and must be
extracted using @code{tar} before you can build Emacs.  Typically, the
extraction command would look like

@example
tar -xvvf emacs-@value{VER}.tar
@end example

@noindent
The @samp{x} indicates that we want to extract files from this tarfile,
the two @samp{v}s force verbose output, and the @samp{f} tells
@code{tar} to use a disk file, rather than one on the tape drive.

If you're using GNU @code{tar} (available at mirrors of
@file{ftp.gnu.org}), you can combine this step and the previous one by
using the command

@example
tar -zxvvf emacs-@value{VER}.tar.gz
@end example

@noindent
The additional @samp{z} at the beginning of the options list tells GNU
@code{tar} to uncompress the file with @code{gunzip} before extracting
the tarfile's components.

@end itemize

At this point, the Emacs sources (all 70+ megabytes of them) should be
sitting in a directory called @file{emacs-@value{VER}}.  On most common
Unix and Unix-like systems, you should be able to compile Emacs (with X
Window system support) with the following commands:

@example
cd emacs-@value{VER}       # change directory to emacs-@value{VER}
./configure         # configure Emacs for your particular system
make                # use Makefile to build components, then Emacs
@end example

If the @code{make} completes successfully, the odds are fairly good that
the build has gone well.  (@xref{Problems building Emacs}, if you weren't
successful.)

By default, Emacs is installed in the following directories:

@table @file
@item /usr/local/bin
binaries.

@item /usr/local/share/emacs/@value{VER}
Lisp code and support files.

@item /usr/local/info
Info documentation.
@end table

To install files in those default directories, become the superuser and
type

@example
make install
@end example

Note that @samp{make install} will overwrite @file{/usr/local/bin/emacs}
and any Emacs Info files that might be in @file{/usr/local/info}.

Much more verbose instructions (with many more hints and suggestions)
come with the Emacs sources, in the file @file{INSTALL}.

@node Updating Emacs, Problems building Emacs, Installing Emacs, Compiling and installing Emacs
@section How do I update Emacs to the latest version?
@cindex Updating Emacs

@xref{Installing Emacs}, and follow the instructions there for
installation.

Most files are placed in version-specific directories.  Emacs
@value{VER}, for instance, places files in
@file{/usr/local/share/emacs/@value{VER}}.

Upgrading should overwrite only, @file{/usr/local/bin/emacs} (the Emacs
binary) and documentation in @file{/usr/local/info}.  Back up these
files before you upgrade, and you shouldn't have too much trouble.

@node Problems building Emacs, Linking with -lX11 fails, Updating Emacs, Compiling and installing Emacs
@section What should I do if I have trouble building Emacs?
@cindex Problems building Emacs
@cindex Errors when building Emacs

First look in the file @file{etc/PROBLEMS} (where you unpack the Emacs
source) to see if there is already a solution for your problem.  Next,
look for other questions in this FAQ that have to do with Emacs
installation and compilation problems.

If you'd like to have someone look at your problem and help solve it,
see @ref{Help installing Emacs}.

If you cannot find a solution in the documentation, send a message to
@email{bug-gnu-emacs@@gnu.org}.

Please don't post it to @uref{news:gnu.emacs.help} or send e-mail to
@email{help-gnu-emacs@@gnu.org}.  For further guidelines, see
@ref{Guidelines for newsgroup postings} and @ref{Reporting bugs}.

@node Linking with -lX11 fails,  , Problems building Emacs, Compiling and installing Emacs
@section Why does linking Emacs with -lX11 fail?
@cindex Linking with -lX11 fails
@cindex lX11, linking fails with

Emacs needs to be linked with the static version of the X11 library,
@file{libX11.a}.  This may be missing.

On OpenWindows, you may need to use @code{add_services} to add the
"OpenWindows Programmers" optional software category from the CD-ROM.

On HP-UX 8.0, you may need to run @code{update} again to load the
X11-PRG ``fileset''.  This may be missing even if you specified ``all
filesets'' the first time.  If @file{libcurses.a} is missing, you may
need to load the ``Berkeley Development Option.''

@email{zoo@@armadillo.com, David Zuhn} says that MIT X builds shared
libraries by default, and only shared libraries, on those platforms that
support them.  These shared libraries can't be used when undumping
@code{temacs} (the last stage of the Emacs build process).  To get
regular libraries in addition to shared libraries, add this to
@file{site.cf}:

@example
#define ForceNormalLib YES
@end example

Other systems may have similar problems.  You can always define
@code{CANNOT_DUMP} and link with the shared libraries instead.

@cindex X Menus don't work
To get the Xmenu stuff to work, you need to find a copy of MIT's
@file{liboldX.a}.

@c ------------------------------------------------------------
@node Finding Emacs and related packages, Major packages and programs, Compiling and installing Emacs, Top
@chapter Finding Emacs and related packages
@cindex Finding Emacs and related packages

@menu
* Finding Emacs on the Internet::
* Finding a package with particular functionality::
* Packages that do not come with Emacs::
* Current GNU distributions::
* Difference between Emacs and XEmacs::
* Emacs for MS-DOS::
* Emacs for Windows::
* Emacs for OS/2::
* Emacs for Atari ST::
* Emacs for the Amiga ::
* Emacs for NeXTSTEP::
* Emacs for Apple computers::
* Emacs for VMS and DECwindows::
* Modes for various languages::
* Translating names to IP addresses::
@end menu

@node Finding Emacs on the Internet, Finding a package with particular functionality, Finding Emacs and related packages, Finding Emacs and related packages
@section Where can I get Emacs on the net (or by snail mail)?
@cindex Finding Emacs on the Internet
@cindex Snail mail, ordering Emacs via
@cindex Postal service, ordering Emacs via
@cindex Distribution, retrieving Emacs
@cindex Internet, retrieving from

Look in the files @file{etc/DISTRIB} and @file{etc/FTP} for
information on nearby archive sites.  If you don't already have Emacs,
see @ref{Informational files for Emacs}, for how to get these files.

@xref{Installing Emacs}, for information on how to obtain and build the latest
version of Emacs, and see @ref{Current GNU distributions}, for a list of
archive sites that make GNU software available.

@node Finding a package with particular functionality, Packages that do not come with Emacs, Finding Emacs on the Internet, Finding Emacs and related packages
@section How do I find a Emacs Lisp package that does XXX?
@cindex Package, finding
@cindex Finding an Emacs Lisp package
@cindex Functionality, finding a particular package

First of all, you should check to make sure that the package isn't
already available.  For example, typing @kbd{M-x apropos @key{RET}
wordstar @key{RET}} lists all functions and variables containing the
string @samp{wordstar}.

It is also possible that the package is on your system, but has not been
loaded.  To see which packages are available for loading, look through
your computer's lisp directory (@pxref{File-name conventions}).  The Lisp
source to most packages contains a short description of how they
should be loaded, invoked, and configured---so before you use or
modify a Lisp package, see if the author has provided any hints in the
source code.

The command @kbd{C-h p} (@code{finder-by-keyword}) allows you to browse
the constituent Emacs packages.

For advice on how to find extra packages that are not part of Emacs,
see @ref{Packages that do not come with Emacs}.

@node Packages that do not come with Emacs, Current GNU distributions, Finding a package with particular functionality, Finding Emacs and related packages
@section Where can I get Emacs Lisp packages that don't come with Emacs?
@cindex Unbundled packages
@cindex Finding other packages
@cindex Lisp packages that do not come with Emacs
@cindex Packages, those that do not come with Emacs
@cindex Emacs Lisp List
@cindex Emacs Lisp Archive

@uref{http://www.anc.ed.ac.uk/~stephen/emacs/ell.html, The Emacs Lisp
List (ELL)}, maintained by @email{stephen@@anc.ed.ac.uk, Stephen Eglen},
aims to provide one compact list with links to all of the current Emacs
lisp files on the internet.  The ELL can be browsed over the web, or
from Emacs with @uref{http://www.anc.ed.ac.uk/~stephen/emacs/ell.el, 
the @file{ell} package}.

Many authors post their packages to the @uref{news:gnu.emacs.sources,
Emacs sources newsgroup}.  You can search the archives of this
group with @uref{http://groups.google.com, Google}, for example.

Several packages are stored in
@uref{http://emacswiki.org/elisp/, the Lisp area of the Emacs Wiki}.

For a long time, the Emacs Lisp Archive provided a central repository
for Emacs packages.  Sadly, it has not been active for some time,
although you can still access the old files at

@uref{ftp://ftp.cis.ohio-state.edu/pub/emacs-lisp/WWW/index.html}

@node Current GNU distributions, Difference between Emacs and XEmacs, Packages that do not come with Emacs, Finding Emacs and related packages
@section Where can I get other up-to-date GNU stuff?
@cindex Current GNU distributions
@cindex Sources for current GNU distributions
@cindex Stuff, current GNU
@cindex Up-to-date GNU stuff
@cindex Finding current GNU software
@cindex Official GNU software sites

The most up-to-date official GNU software is normally kept at

@uref{ftp://ftp.gnu.org/pub/gnu}

Read the files @file{etc/DISTRIB} and @file{etc/FTP} for more
information.

A list of sites mirroring @samp{ftp.gnu.org} can be found at

@uref{http://www.gnu.org/order/ftp.html}

@node Difference between Emacs and XEmacs, Emacs for MS-DOS, Current GNU distributions, Finding Emacs and related packages
@section What is the difference between Emacs and XEmacs (formerly "Lucid Emacs")?
@cindex XEmacs
@cindex Difference Emacs and XEmacs
@cindex Lucid Emacs
@cindex Epoch

First of all, they're both GNU Emacs.  XEmacs is just as much a later
version of GNU Emacs as the FSF-distributed version.  This FAQ refers to
the latest version to be distributed by the FSF as ``Emacs,'' partly
because the XEmacs maintainers now refer to their product using the
``XEmacs'' name, and partly because there isn't any accurate way to
differentiate between the two without getting mired in paragraphs of
legalese and history.

XEmacs, which began life as Lucid Emacs, is based on an early version of
Emacs 19 and Epoch, an X-aware version of Emacs 18.

Emacs (i.e., the version distributed by the FSF) has a larger installed
base and now always contains the MULE multilingual facilities.
XEmacs can do some clever tricks with X and MS-Windows, such as
putting arbitrary graphics in a buffer.  Similar facilities have been
implemented for Emacs as part of a new redisplay implementation for
Emacs 21, and are available in the latest Emacs releases.
Emacs and XEmacs each come with
Lisp packages that are lacking in the other; RMS says that the FSF would
include more packages that come with XEmacs, but that the XEmacs
maintainers don't always keep track of the authors of contributed code,
which makes it impossible for the FSF to have certain legal papers
signed.  (Without these legal papers, the FSF will not distribute Lisp
packages with Emacs.)  The two versions have some
significant differences at the Lisp programming level.

Many XEmacs features have found their way into recent versions of Emacs,
and more features can be expected in the future, but there are still many
differences between the two.

The latest stable branch of XEmacs as of this writing is 21.4; you can
get it at

@uref{ftp://ftp.xemacs.org/pub/xemacs/xemacs-21.4/xemacs-21.4.12.tar.gz}

More information about XEmacs, including a list of frequently asked
questions (FAQ), is available at

@uref{http://www.xemacs.org/}

@node Emacs for MS-DOS, Emacs for Windows, Difference between Emacs and XEmacs, Finding Emacs and related packages
@section Where can I get Emacs for my PC running MS-DOS?
@cindex MS-DOS, Emacs for
@cindex DOS, Emacs for
@cindex Compiling Emacs for DOS
@cindex Emacs for MS-DOS
@cindex Tools needed to compile Emacs under DOS

A pre-built binary distribution of Emacs is available from the
SimTel.NET archives.  This version apparently works under MS-DOS and
Windows (3.X, 9X, ME, NT, and 2000) and supports long file names under
Windows 9X, Windows ME, and Windows 2000.  More information is available
from

@uref{http://www.simtel.net/pub/djgpp/v2gnu/emacs.README}

The binary itself is available in the files @file{em*.zip} in the
directory

@uref{http://www.simtel.net/pub/djgpp/v2gnu/}

If you prefer to compile Emacs for yourself, you can do so with the
current distribution directly.  You will need a 386 (or
better) processor, and to be running MS-DOS 3.0 or later.  According to
@email{eliz@@is.elta.co.il, Eli Zaretskii} and
@email{hankedr@@dms.auburn.edu, Darrel Hankerson}, you will need the
following:

@table @emph

@item Compiler
DJGPP version 1.12 maint 1 or later.  Djgpp 2.0 or later is
recommended, since 1.x is very old an unmaintained.  Djgpp 2 supports
long file names on Windows 9X/ME/2K.

You can get the latest release of DJGPP by retrieving all of
the files in

@uref{http://www.simtel.net/pub/gnu/djgpp/v2*}

@item Unpacking program
The easiest way is to use @code{djtar} which comes with DJGPP v2.x,
because it can open gzip'ed tarfiles (i.e., those ending with
@file{.tar.gz}) in one step.  @code{Djtar} comes in
@file{djdev@var{nnn}.zip} archive (where @var{nnn} is the DJGPP version
number), from the URL mentioned above.

@strong{Warning!}  Do @strong{not} use the popular WinZip program to
unpack the Emacs distribution!  WinZip is known to corrupt some of the
files by converting them to the DOS CR-LF format, it doesn't always
preserve the directory structure recorded in the compressed Emacs
archive, and commits other atrocities.  Some of these problems could
actually prevent Emacs from building successfully!

@item make, mv, sed, and rm
All of these utilities are available at

@uref{http://www.simtel.net/pub/gnu/djgpp/v2gnu}

16-bit utilities can be found in GNUish, at

@uref{http://www.simtel.net/pub/gnuish/}

@noindent
(@code{mv} and @code{rm} are in the Fileutils package, @code{sed} and
@code{make} are each one in a separate package named after them.)

@end table

The files @file{INSTALL} (near its end) and @file{etc/PROBLEMS} in the
directory of the Emacs sources contains some additional information
regarding Emacs under MS-DOS.

For a list of other MS-DOS implementations of Emacs (and Emacs
look-alikes), consult the list of "Emacs implementations and literature,"
available at

@uref{ftp://rtfm.mit.edu/pub/usenet/comp.emacs/}

Note that while many of these programs look similar to Emacs, they often
lack certain features, such as the Emacs Lisp extension language.

@node Emacs for Windows, Emacs for OS/2, Emacs for MS-DOS, Finding Emacs and related packages
@section Where can I get Emacs for Microsoft Windows
@cindex FAQ for NT Emacs
@cindex Emacs for MS-Windows
@cindex Microsoft Windows, Emacs for
@cindex Windows 9X, ME, NT, 2K, and CE, Emacs for

For information on Emacs for Windows 95 and NT, read the FAQ produced by
@email{voelker@@cs.washington.edu, Geoff Voelker}, available at

@uref{http://www.gnu.org/software/emacs/windows/ntemacs.html}

@xref{Emacs for MS-DOS}, for Windows 3.1.

A port of Emacs 20.7 for Windows CE, based on NTEmacs, is available at

@uref{http://www.rainer-keuchel.de/software.html}

@noindent
This port was done by @email{coyxc@@rainer-keuchel.de, Rainer Keuchel},
and supports all Emacs features except async subprocesses and menus.
You will need MSVC 6.0 and a Windows CE SDK to build this port.

@node Emacs for OS/2, Emacs for Atari ST, Emacs for Windows, Finding Emacs and related packages
@section Where can I get Emacs for my PC running OS/2?
@cindex OS/2, Emacs for

Emacs 20.6 is ported for emx on OS/2 2.0 or 2.1, and is available at

@uref{ftp://hobbes.nmsu.edu/pub/os2/apps/editors/emacs/e206*.zip}

@noindent
and also at

@uref{http://archiv.leo.org/pub/comp/os/os2/leo/gnu/emacs%2d20/}

Instructions for installation, basic setup, and other useful information
for OS/2 users of Emacs can be found at

@uref{http://userpage.fu-berlin.de/~oheiabbd/emacs/emacs206-os2.html}

@node Emacs for Atari ST, Emacs for the Amiga , Emacs for OS/2, Finding Emacs and related packages
@section Where can I get Emacs for my Atari ST?
@cindex Atari ST, Emacs for
@cindex TOS, Emacs for