\input texinfo @c -*-texinfo-*- -*- coding: latin-1 -*- @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 21.1 @c The @ifinfo stuff only appears in the Info version @ifinfo @dircategory Emacs @direntry * Emacs FAQ: (efaq). Frequently Asked Questions about Emacs. @end direntry Copyright 1994,1995,1996,1997,1998,1999,2000 Reuven M. Lerner@* Copyright 1992,1993 Steven Byrnes@* Copyright 1990,1991,1992 Joseph Brian Wells@* 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 ifinfo @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 Copyright @copyright{} 1994,1995,1996,1997,1998,1999,2000 Reuven M. Lerner@* Copyright @copyright{} 1992,1993 Steven Byrnes@* Copyright @copyright{} 1990,1991,1992 Joseph Brian Wells@* 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 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. If you have any suggestions or questions, please contact @email{emacs-faq@@lerner.co.il, the FAQ maintainers}. @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{M-C-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{M-C-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 @uref{news: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}. As of this writing, the archives are not yet working. Web-based Usenet search services, such as @uref{http://www.dejanews.com, DejaNews}, 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}, and also the files @file{etc/ORDERS}, @file{ORDERS.EUROPE}, and @file{ORDERS.JAPAN}. @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 copy of @cindex Emacs manual, obtaining a printed 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} and the file @file{etc/ORDERS}. @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} 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} and in the file @file{etc/ORDERS}. 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 appearence 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 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. @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 As of Emacs 21.1, 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). @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{M-C-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 starts a subprocess running a program called @samp{emacsserver}. @samp{emacsserver} 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 how @samp{emacsserver} was compiled. 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} which is available in the Emacs Lisp Archive (@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} @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. To avoid this hassle, try one of the many packages available from the Emacs Lisp Archive (@pxref{Packages that do not come with Emacs}.) Look up ``fill'' and ``indent'' in the Lisp Code Directory 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{M-C-f} (@code{forward-sexp}) and @kbd{M-C-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 try @file{cpp.el}, available at the Emacs Lisp Archive (@pxref{Packages that do not come 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{Resources X, Resources X, 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{M-C-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{Misc X, Misc X, 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, available from the Lisp Code Archive (@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 scrollng 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 Highlighing 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++} from the Emacs Lisp Archive (@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 do I get these strange escape sequences when I run @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. Check the Lisp Code Directory (@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 guid