This is ../info/efaq, produced by makeinfo version 4.0f from faq.texi.
INFO-DIR-SECTION Emacs
START-INFO-DIR-ENTRY
* Emacs FAQ: (efaq). Frequently Asked Questions about Emacs.
END-INFO-DIR-ENTRY
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.]
File: efaq, Node: Wrapping words automatically, Next: Spell-checkers, Prev: Controlling case sensitivity, Up: Common requests
How do I make Emacs wrap words for me?
======================================
Use `auto-fill-mode', activated by typing `M-x auto-fill-mode'. The
default maximum line width is 70, determined by the variable
`fill-column'. To learn how to turn this on automatically, see *Note
Turning on auto-fill by default::.
File: efaq, Node: Spell-checkers, Next: Checking TeX and *roff documents, Prev: Wrapping words automatically, Up: Common requests
Where can I get a better spelling checker for Emacs?
====================================================
Use Ispell. *Note Ispell::.
File: efaq, Node: Checking TeX and *roff documents, Next: Changing load-path, Prev: Spell-checkers, Up: Common requests
How can I spell-check TeX or *roff documents?
=============================================
Use Ispell. Ispell can handle TeX and *roff documents. *Note
Ispell::.
File: efaq, Node: Changing load-path, Next: Using an already running Emacs process, Prev: Checking TeX and *roff documents, Up: Common requests
How do I change `load-path'?
============================
In general, you should only add to the `load-path'. You can add
directory /DIR/SUBDIR to the load path like this:
(setq load-path (cons "/dir/subdir/" load-path))
To do this relative to your home directory:
(setq load-path (cons "~/mysubdir/" load-path)
File: efaq, Node: Using an already running Emacs process, Next: Compiler error messages, Prev: Changing load-path, Up: Common requests
How do I use an already running Emacs from another window?
==========================================================
`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.
* Setup:
Emacs must have executed the `server-start' function for
`emacsclient' to work. This can be done either by a command line
option:
emacs -f server-start
or by invoking `server-start' from `.emacs':
(if (SOME CONDITIONS ARE MET) (server-start))
When this is done, Emacs starts a subprocess running a program
called `emacsserver'. `emacsserver' creates a Unix domain socket.
The socket is either named `.emacs_server', in the user's home
directory, or `esrv-USERID-SYSTEMNAME', in the `/tmp' directory,
depending on how `emacsserver' was compiled.
To get your news reader, mail reader, etc., to invoke
`emacsclient', try setting the environment variable `EDITOR' (or
sometimes `VISUAL') to the value `emacsclient'. You may have to
specify the full pathname of the `emacsclient' program instead.
Examples:
# csh commands:
setenv EDITOR emacsclient
# using full pathname
setenv EDITOR /usr/local/emacs/etc/emacsclient
# sh command:
EDITOR=emacsclient ; export EDITOR
* Normal use:
When `emacsclient' is run, it connects to the `.emacs_server'
socket and passes its command line options to `server'. When
`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 `C-x #'
(or `M-x server-edit') to indicate this. If there is another
buffer requested by `emacsclient', Emacs will switch to it;
otherwise `emacsclient' will exit, signaling the calling program
to continue.
`emacsclient' and `server' must be running on machines which share
the same filesystem for this to work. The pathnames that
`emacsclient' specifies should be correct for the filesystem that
the Emacs process sees. The Emacs process should not be suspended
at the time `emacsclient' is invoked. On Unix and GNU/Linux
systems, `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 `screen' program.
There is an enhanced version of `emacsclient'/server called
`gnuserv', written by Andy Norman <ange@hplb.hpl.hp.com> which is
available in the Emacs Lisp Archive (*note Packages that do not
come with Emacs::). `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 `gnuserv' is available at
`ftp://ftp.wellfleet.com/netman/psmith/emacs/gnuserv-2.1alpha.tar.gz'
File: efaq, Node: Compiler error messages, Next: Indenting switch statements, Prev: Using an already running Emacs process, Up: Common requests
How do I make Emacs recognize my compiler's funny error messages?
=================================================================
The variable `compilation-error-regexp-alist' helps control how
Emacs parses your compiler output. It is a list of triplets of the
form: `(REGEXP FILE-IDX LINE-IDX)', where REGEXP, FILE-IDX and LINE-IDX
are strings. To help determine what the constituent elements should
be, load `compile.el' and then type `C-h v
compilation-error-regexp-alist <RET>' to see the current value. A good
idea is to look at `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:
(setq compilation-error-regexp-alist
(cons '(REGEXP FILE-IDX LINE-IDX)
compilation-error-regexp-alist))
File: efaq, Node: Indenting switch statements, Next: Customizing C and C++ indentation, Prev: Compiler error messages, Up: Common requests
How do I change the indentation for `switch'?
=============================================
Many people want to indent their `switch' statements like this:
f()
{
switch(x) {
case A:
x1;
break;
case B:
x2;
break;
default:
x3;
}
}
The solution at first appears to be: set `c-indent-level' to 4 and
`c-label-offset' to -2. However, this will give you an indentation
spacing of four instead of two.
The _real_ solution is to use `cc-mode' (the default mode for C
programming in Emacs 20 and later) and add the following line to yoyr
`.emacs':
(c-set-offset 'case-label '+)
There appears to be no way to do this with the old `c-mode'.
File: efaq, Node: Customizing C and C++ indentation, Next: Horizontal scrolling, Prev: Indenting switch statements, Up: Common requests
How to customize indentation in C, C++, and Java buffers?
=========================================================
The Emacs `cc-mode' features an interactive procedure for
customizing the indentation style, which is fully explained in the `CC
Mode' manual that is part of the Emacs distribution, see *Note
Customization Indentation: (ccmode)Customizing Indentation. Here's a
short summary of the procedure:
1. Go to the beginning of the first line where you don't like the
indentation and type `C-c C-o'. Emacs will prompt you for the
syntactic symbol; type <RET> to accept the default it suggests.
2. Emacs now prompts for the offset of this syntactic symbol, showing
the default (the current definition) inside parentheses. You can
choose one of these:
`0'
No extra indentation.
`+'
Indent one basic offset.
`-'
Outdent one basic offset.
`++'
Indent two basic offsets
`--'
Outdent two basic offsets.
`*'
Indent half basic offset.
`/'
Outdent half basic offset.
3. After choosing one of these symbols, type `C-c C-q' to reindent
the line or the block according to what you just specified.
4. If you don't like the result, go back to step 1. Otherwise, add
the following line to your `.emacs':
(c-set-offset 'SYNTACTIC-SYMBOL OFFSET)
where SYNTACTIC-SYMBOL is the name Emacs shows in the minibuffer
when you type `C-c C-o' at the beginning of the line, and OFFSET
is one of the indentation symbols listed above (`+', `/', `0',
etc.) that you've chosen during the interactive procedure.
5. Go to the next line whose indentation is not to your liking and
repeat the process there.
It is recommended to put all the resulting `(c-set-offset ...)'
customizations inside a C mode hook, like this:
(defun my-c-mode-hook ()
(c-set-offset ...)
(c-set-offset ...))
(add-hook 'c-mode-hook 'my-c-mode-hook)
Using `c-mode-hook' avoids the need to put a `(require 'cc-mode)' into
your `.emacs' file, because `c-set-offset' might be unavailable when
`cc-mode' is not loaded.
Note that `c-mode-hook' runs for C source files only; use
`c++-mode-hook' for C++ sources, `java-mode-hook' for Java sources,
etc. If you want the same customizations to be in effect in _all_
languages supported by `cc-mode', use `c-mode-common-hook'.
File: efaq, Node: Horizontal scrolling, Next: Overwrite mode, Prev: Customizing C and C++ indentation, Up: Common requests
How can I make Emacs automatically scroll horizontally?
=======================================================
In Emacs 21 and later, this is on by default: if the variable
`truncate-lines' is non-`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 `hscroll-mode'. Here is some information from
the documentation, available by typing `C-h f hscroll-mode <RET>':
Automatically scroll horizontally when the point moves off the left
or right edge of the window.
- Type `M-x hscroll-mode' to enable it in the current buffer.
- Type `M-x hscroll-global-mode' to enable it in every buffer.
- `turn-on-hscroll' is useful in mode hooks as in:
(add-hook 'text-mode-hook 'turn-on-hscroll)
- `hscroll-margin' controls how close the cursor can get to the edge
of the window.
- `hscroll-step-percent' controls how far to jump once we decide to
do so.
File: efaq, Node: Overwrite mode, Next: Turning off beeping, Prev: Horizontal scrolling, Up: Common requests
How do I make Emacs "typeover" or "overwrite" instead of inserting?
===================================================================
`M-x overwrite-mode' (a minor mode). This toggles `overwrite-mode'
on and off, so exiting from `overwrite-mode' is as easy as another `M-x
overwrite-mode'.
On some systems, <Insert> toggles `overwrite-mode' on and off.
File: efaq, Node: Turning off beeping, Next: Turning the volume down, Prev: Overwrite mode, Up: Common requests
How do I stop Emacs from beeping on a terminal?
===============================================
Martin R. Frank <martin@cc.gatech.edu> writes:
Tell Emacs to use the "visible bell" instead of the audible bell,
and set the visible bell to nothing.
That is, put the following in your `TERMCAP' environment variable
(assuming you have one):
... :vb=: ...
And evaluate the following Lisp form:
(setq visible-bell t)
File: efaq, Node: Turning the volume down, Next: Automatic indentation, Prev: Turning off beeping, Up: Common requests
How do I turn down the bell volume in Emacs running under X?
============================================================
On X Window system, you can adjust the bell volume and duration for
all programs with the shell command `xset'.
Invoking `xset' without any arguments produces some basic
information, including the following:
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
File: efaq, Node: Automatic indentation, Next: Matching parentheses, Prev: Turning the volume down, Up: Common requests
How do I tell Emacs to automatically indent a new line to the indentation of the previous line?
===============================================================================================
Such behavior is automatic in Emacs 20 and later. From the
`etc/NEWS' file for Emacs 20.2:
** 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). <TAB> in Text
mode now runs the command `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.
If you have `auto-fill-mode' turned on (*note Turning on auto-fill
by default::), you can tell Emacs to prefix every line with a certain
character sequence, the "fill prefix". Type the prefix at the
beginning of a line, position point after it, and then type `C-x .'
(`set-fill-prefix') to set the fill prefix. Thereafter, auto-filling
will automatically put the fill prefix at the beginning of new lines,
and `M-q' (`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 (*note Packages that do not come
with Emacs::.) Look up "fill" and "indent" in the Lisp Code Directory
for guidance.
File: efaq, Node: Matching parentheses, Next: Hiding #ifdef lines, Prev: Automatic indentation, Up: Common requests
How do I show which parenthesis matches the one I'm looking at?
===============================================================
As of version 19, Emacs comes with `paren.el', which (when loaded)
will automatically highlight matching parentheses whenever point (i.e.,
the cursor) is located over one. To load `paren.el' automatically,
include the line
(require 'paren)
in your `.emacs' file. Alan Shutko <shutkoa@ugsolutions.com>
reports that as of version 20.1, you must also call `show-paren-mode' in
your `.emacs' file:
(show-paren-mode 1)
Customize will let you turn on `show-paren-mode'. Use `M-x
customize-group <RET> paren-showing <RET>'. From within Customize, you
can also go directly to the "paren-showing" group.
Alternatives to paren include:
* 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.
* `M-C-f' (`forward-sexp') and `M-C-b' (`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.)
* Here is some Emacs Lisp that will make the <%> key show the
matching parenthesis, like in `vi'. In addition, if the cursor
isn't over a parenthesis, it simply inserts a % like normal.
;; 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)))))
File: efaq, Node: Hiding #ifdef lines, Next: Repeating commands, Prev: Matching parentheses, Up: Common requests
In C mode, can I show just the lines that will be left after `#ifdef' commands are handled by the compiler?
===========================================================================================================
`M-x hide-ifdef-mode'. (This is a minor mode.) You might also want
to try `cpp.el', available at the Emacs Lisp Archive (*note Packages
that do not come with Emacs::).
File: efaq, Node: Repeating commands, Next: Valid X resources, Prev: Hiding #ifdef lines, Up: Common requests
Is there an equivalent to the `.' (dot) command of vi?
======================================================
(`.' is the redo command in `vi'. It redoes the last
insertion/deletion.)
As of Emacs 20.3, there is indeed a `repeat' command (`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 `C-x <ESC> <ESC>' (`repeat-complex-command') to
reinvoke commands that used the minibuffer to get arguments. In
`repeat-complex-command' you can type `M-p' and `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. (*note Keyboard
Macros: (emacs)Keyboard Macros.)
If you're really desperate for the `.' command, use VIPER, a `vi'
emulation mode which comes with Emacs, and which appears to support it.
(*Note VIPER::.)
File: efaq, Node: Valid X resources, Next: Evaluating Emacs Lisp code, Prev: Repeating commands, Up: Common requests
What are the valid X resource settings (i.e., stuff in .Xdefaults)?
===================================================================
*note Resources X: (emacs)Resources X.
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.
File: efaq, Node: Evaluating Emacs Lisp code, Next: Changing the length of a Tab, Prev: Valid X resources, Up: Common requests
How do I execute ("evaluate") a piece of Emacs Lisp code?
=========================================================
There are a number of ways to execute ("evaluate", in Lisp lingo) an
Emacs Lisp "form":
* If you want it evaluated every time you run Emacs, put it in a file
named `.emacs' in your home directory. This is known as "your
`.emacs' file," and contains all of your personal customizations.
* You can type the form in the `*scratch*' buffer, and then type
<LFD> (or `C-j') after it. The result of evaluating the form will
be inserted in the buffer.
* In `emacs-lisp-mode', typing `M-C-x' evaluates a top-level form
before or around point.
* Typing `C-x C-e' in any buffer evaluates the Lisp form immediately
before point and prints its value in the echo area.
* Typing `M-:' or `M-x eval-expression' allows you to type a Lisp
form in the minibuffer which will be evaluated once you press
<RET>.
* You can use `M-x load-file' to have Emacs evaluate all the Lisp
forms in a file. (To do this from Lisp use the function `load'
instead.)
The functions `load-library', `eval-region',
`eval-current-buffer', `require', and `autoload' are also useful;
see *Note Emacs Lisp documentation::, if you want to learn more
about them.
File: efaq, Node: Changing the length of a Tab, Next: Inserting > at the beginning of each line, Prev: Evaluating Emacs Lisp code, Up: Common requests
How do I change Emacs's idea of the <TAB> character's length?
=============================================================
Set the variable `default-tab-width'. For example, to set <TAB>
stops every 10 characters, insert the following in your `.emacs' file:
(setq default-tab-width 10)
Do not confuse variable `tab-width' with variable `tab-stop-list'.
The former is used for the display of literal <TAB> characters. The
latter controls what characters are inserted when you press the <TAB>
character in certain modes.
File: efaq, Node: Inserting > at the beginning of each line, Next: Underlining paragraphs, Prev: Changing the length of a Tab, Up: Common requests
How do I insert `>' at the beginning of every line?
===================================================
To do this to an entire buffer, type `M-< M-x replace-regexp <RET> ^
<RET> > <RET>'.
To do this to a region, use `string-insert-rectangle'. Set the mark
(`C-<SPC>') at the beginning of the first line you want to prefix, move
the cursor to last line to be prefixed, and type `M-x
string-insert-rectangle <RET>'. To do this for the whole buffer, type
`C-x h M-x string-insert-rectangle <RET>'.
If you are trying to prefix a yanked mail message with `>', you
might want to set the variable `mail-yank-prefix'. Better yet, use the
Supercite package (*note Supercite::), which provides flexible citation
for yanked mail and news messages; it is included in Emacs since
version 19.20. *Note Changing the included text prefix::, for
additional information.
File: efaq, Node: Underlining paragraphs, Next: Repeating a command as many times as possible, Prev: Inserting > at the beginning of each line, Up: Common requests
How do I insert "_^H" before each character in a region to get an underlined paragraph?
=======================================================================================
Mark the region and then type `M-x underline-region <RET>'.
File: efaq, Node: Repeating a command as many times as possible, Next: Forcing the cursor to remain in the same column, Prev: Underlining paragraphs, Up: Common requests
How do I repeat a command as many times as possible?
====================================================
Use `C-x (' and `C-x )' to make a keyboard macro that invokes the
command and then type `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
`C-x z', see *Note Repeating commands::.
File: efaq, Node: Forcing the cursor to remain in the same column, Next: Forcing Emacs to iconify itself, Prev: Repeating a command as many times as possible, Up: Common requests
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?
====================================================================================================================================
`M-x picture-mode'.
File: efaq, Node: Forcing Emacs to iconify itself, Next: Using regular expressions, Prev: Forcing the cursor to remain in the same column, Up: Common requests
How do I tell Emacs to iconify itself?
======================================
`C-z' iconifies Emacs when running under X and suspends Emacs
otherwise. *note Misc X: (emacs)Misc X.
File: efaq, Node: Using regular expressions, Next: Replacing text across multiple files, Prev: Forcing Emacs to iconify itself, Up: Common requests
How do I use regexps (regular expressions) in Emacs?
====================================================
*note Regexps: (emacs)Regexps.
The `or' operator is `\|', not `|', and the grouping operators are
`\(' and `\)'. Also, the string syntax for a backslash is `\\'. To
specify a regular expression like `xxx\(foo\|bar\)' in a Lisp string,
use `xxx\\(foo\\|bar\\)'.
Note the doubled backslashes!
* Unlike in Unix `grep', `sed', etc., a complement character set
(`[^...]') can match a newline character (<LFD> a.k.a. `C-j'
a.k.a. `\n'), unless newline is mentioned as one of the characters
not to match.
* The character syntax regexps (e.g., `\sw') are not meaningful
inside character set regexps (e.g., `[aeiou]'). (This is actually
typical for regexp syntax.)
File: efaq, Node: Replacing text across multiple files, Next: Documentation for etags, Prev: Using regular expressions, Up: Common requests
How do I perform a replace operation across more than one file?
===============================================================
The "tags" feature of Emacs includes the command
`tags-query-replace' which performs a query-replace across all the
files mentioned in the `TAGS' file. *note Tags Search: (emacs)Tags
Search.
As of Emacs 19.29, Dired mode (`M-x dired <RET>', or `C-x d')
supports the command `dired-do-query-replace', which allows users to
replace regular expressions in multiple files.
File: efaq, Node: Documentation for etags, Next: Disabling backups, Prev: Replacing text across multiple files, Up: Common requests
Where is the documentation for `etags'?
=======================================
The `etags' man page should be in the same place as the `emacs' man
page.
Quick command-line switch descriptions are also available. For
example, `etags -H'.
File: efaq, Node: Disabling backups, Next: Disabling auto-save-mode, Prev: Documentation for etags, Up: Common requests
How do I disable backup files?
==============================
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 `dired-x' by adding the following to your `.emacs' file:
(add-hook 'dired-load-hook
(lambda ()
(load "dired-x")))
With `dired-x' loaded, `M-o' toggles omitting in each dired buffer.
You can make omitting the default for new dired buffers by putting the
following in your `.emacs':
(add-hook 'dired-mode-hook 'dired-omit-toggle)
If you're tired of seeing backup files whenever you do an `ls' at
the Unix shell, try GNU `ls' with the `-B' option. GNU `ls' is part of
the GNU Fileutils package, available from `ftp.gnu.org' and its mirrors
(*note Current GNU distributions::).
To disable or change the way backups are made, *note (emacs)Backup
Names::.
Beginning with Emacs 21.1, you can control where Emacs puts backup
files by customizing the variable `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 `("." . DIR)' to force Emacs to put *all* backup
files in the directory `dir'.
File: efaq, Node: Disabling auto-save-mode, Next: Going to a line by number, Prev: Disabling backups, Up: Common requests
How do I disable `auto-save-mode'?
==================================
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 `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 `auto-save'
package, available from the Lisp Code Archive (*note Packages that do
not come with Emacs::). This package also allows you to place all
auto-save files in one directory, such as `/tmp'.
To disable or change how `auto-save-mode' works, *note (emacs)Auto
Save::.
File: efaq, Node: Going to a line by number, Next: Modifying pull-down menus, Prev: Disabling auto-save-mode, Up: Common requests
How can I go to a certain line given its number?
================================================
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 `M-x compile' and `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
`*compilation*', and lets you visit the locus of each message in the
source. Type `C-x `' to step through the offending lines one by one.
Click `Mouse-2' or press <RET> on a message text in the `*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 `M-x
goto-line <RET>'. Emacs will prompt you for the number of the line and
go to that line.
You can do this faster by invoking `goto-line' with a numeric
argument that is the line's number. For example, `C-u 286 M-x
goto-line <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 `~/.emacs'
file, will bind the sequence `C-x g' to `goto-line':
(global-set-key "\C-xg" 'goto-line)
File: efaq, Node: Modifying pull-down menus, Next: Deleting menus and menu options, Prev: Going to a line by number, Up: Common requests
How can I create or modify new pull-down menu options?
======================================================
Each menu title (e.g., `File', `Edit', `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 `Forward Word'
item to the `Edit' menu thus requires the following Lisp code:
(define-key global-map
[menu-bar edit forward]
'("Forward word" . forward-word))
The first line adds the entry to the global keymap, which includes
global menu bar entries. Replacing the reference to `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 `File' menu would mean
changing the word `edit' in the second line to `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:
(define-key global-map [menu-bar words]
(cons "Words" (make-sparse-keymap "Words")))
The above code creates a new sparse keymap, gives it the name
`Words', and attaches it to the global menu bar. Adding the `Forward
Word' item to this new menu would thus require the following code:
(define-key global-map
[menu-bar words forward]
'("Forward word" . forward-word))
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 `foo', `bar', and `baz' (in that order), the menu
option `baz' would appear at the top, and `foo' would be at the bottom.
One way to avoid this problem is to use the function
`define-key-after', which works the same as `define-key', but lets you
modify where items appear. The following Lisp code would insert the
`Forward Word' item in the `Edit' menu immediately following the `Undo'
item:
(define-key-after
(lookup-key global-map [menu-bar edit])
[forward]
'("Forward word" . forward-word)
'undo)
Note how the second and third arguments to `define-key-after' are
different from those of `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
`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 `Emacs Lisp Reference Manual', under
"Menu Keymaps". (*Note Emacs Lisp documentation::, for information on
this manual.)
File: efaq, Node: Deleting menus and menu options, Next: Turning on syntax highlighting, Prev: Modifying pull-down menus, Up: Common requests
How do I delete menus and menu options?
=======================================
The simplest way to remove a menu is to set its keymap to `nil'.
For example, to delete the `Words' menu (*note Modifying pull-down
menus::), use:
(define-key global-map [menu-bar words] nil)
Similarly, removing a menu option requires redefining a keymap entry
to `nil'. For example, to delete the `Forward word' menu option from
the `Edit' menu (we added it in *Note Modifying pull-down menus::), use:
(define-key global-map [menu-bar edit forward] nil)
File: efaq, Node: Turning on syntax highlighting, Next: Scrolling only one line, Prev: Deleting menus and menu options, Up: Common requests
How do I turn on syntax highlighting?
=====================================
`font-lock-mode' is the standard way to have Emacs perform syntax
highlighting in the current buffer. With `font-lock-mode' turned on,
different types of text will appear in different colors. For instance,
if you turn on `font-lock-mode' in a programming mode, variables will
appear in one face, keywords in a second, and comments in a third.
Earlier versions of Emacs supported hilit19, a similar package. Use
of hilit19 is now considered non-standard, although `hilit19.el' comes
with the stock Emacs distribution. It is no longer maintained.
To turn `font-lock-mode' on within an existing buffer, use `M-x
font-lock-mode <RET>'.
To automatically invoke `font-lock-mode' when a particular major
mode is invoked, set the major mode's hook. For example, to fontify all
`c-mode' buffers, add the following to your `.emacs' file:
(add-hook 'c-mode-hook 'turn-on-font-lock)
To automatically invoke `font-lock-mode' for all major modes, you
can turn on `global-font-lock-mode' by including the following line in
your `.emacs' file:
(global-font-lock-mode 1)
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
`font-lock-global-modes'). If you edit a file in `pie-ala-mode', and
no font-lock definitions have been provided for `pie-ala' files, then
the above setting will have no effect on that particular buffer.
Highlighting a buffer with `font-lock-mode' can take quite a while,
and cause an annoying delay in display, so several features exist to
work around this.
In Emacs 21 and later, turning on `font-lock-mode' automatically
activates the new "Just-In-Time fontification" provided by
`jit-lock-mode'. `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
`jit-lock-mode', type `C-h f jit-lock-mode <RET>'.
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
`font-lock-maximum-decoration' in your `.emacs' file, with a `nil'
value indicating default (usually minimum) decoration, and a `t' value
indicating the maximum decoration. For the gaudiest possible look,
then, include the line
(setq font-lock-maximum-decoration t)
in your `.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 `font-lock-maximum-decoration'
with `C-h v' (or `M-x describe-variable <RET>').
You might also want to investigate `fast-lock-mode' and
`lazy-lock-mode', versions of `font-lock-mode' that speed up
highlighting. These are the alternatives for `jit-lock-mode' in
versions of Emacs before 21.1. The advantage of `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 `lazy-lock-mode' by
typing `C-h f `lazy-lock-mode'' (`M-x describe-function <RET>
lazy-lock-mode <RET>').
Also see the documentation for the function `font-lock-mode',
available by typing `C-h f font-lock-mode' (`M-x describe-function
<RET> font-lock-mode <RET>').
For more information on font-lock mode, take a look at the
`font-lock-mode' FAQ, maintained by Jari Aalto
<jari.aalto@ntc.nokia.com> at
`ftp://cs.uta.fi/pub/ssjaaa/ema-font.gui'
To print buffers with the faces (i.e., colors and fonts) intact, use
`M-x ps-print-buffer-with-faces' or `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 `ps-printer-name', `ps-lpr-command', and
`ps-lpr-switches' for more details.
File: efaq, Node: Scrolling only one line, Next: Replacing highlighted text, Prev: Turning on syntax highlighting, Up: Common requests
How can I force Emacs to scroll only one line when I move past the bottom of the screen?
========================================================================================
Place the following Lisp form in your `.emacs' file:
(setq scroll-step 1)
*note Scrolling: (emacs)Scrolling.
File: efaq, Node: Replacing highlighted text, Next: Editing MS-DOS files, Prev: Scrolling only one line, Up: Common requests
How can I replace highlighted text with what I type?
====================================================
Use `delete-selection-mode', which you can start automatically by
placing the following Lisp form in your `.emacs' file:
(delete-selection-mode t)
According to the documentation string for `delete-selection-mode'
(which you can read using `M-x describe-function <RET>
delete-selection-mode <RET>'):
When ON, typed text replaces the selection if the selection is
active. When OFF, typed text is just inserted at point.
This mode also allows you to delete (not kill) the highlighted
region by pressing <DEL>.
File: efaq, Node: Editing MS-DOS files, Next: Filling paragraphs with a single space, Prev: Replacing highlighted text, Up: Common requests
How can I edit MS-DOS files using Emacs?
========================================
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 `(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 (`\') will appear in the mode line.
If you are running a version of Emacs before 20.1, get `crypt++'
from the Emacs Lisp Archive (*note Packages that do not come with
Emacs::). Among other things, `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.
File: efaq, Node: Filling paragraphs with a single space, Next: Escape sequences in shell output, Prev: Editing MS-DOS files, Up: Common requests
How can I tell Emacs to fill paragraphs with a single space after each period?
==============================================================================
Ulrich Mueller <ulm@vsnhd1.cern.ch> suggests adding the following
two lines to your `.emacs' file:
(setq sentence-end "[.?!][]\"')}]*\\($\\|[ \t]\\)[ \t\n]*")
(setq sentence-end-double-space nil)
File: efaq, Node: Escape sequences in shell output, Prev: Filling paragraphs with a single space, Up: Common requests
Why do I get these strange escape sequences when I run
======================================================
`ls' from the Shell mode?
This happens because `ls' is aliased to `ls --color' in your shell
init file. You have two alternatives to solve this:
* Make the alias conditioned on the `EMACS' variable in the
environment. When Emacs runs a subsidiary shell, it exports the
`EMACS' variable with the value `t' to that shell. You can
unalias `ls' when that happens, thus limiting the alias to your
interactive sessions.
* Install the `ansi-color' package (bundled with Emacs 21.1 and
later), which converts these ANSI escape sequences into colors.
File: efaq, Node: Bugs and problems, Next: Compiling and installing Emacs, Prev: Common requests, Up: Top
Bugs and problems
*****************
The Emacs manual lists some common kinds of trouble users could get
into, see *Note Dealing with Emacs Trouble: (emacs)Lossage, 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 *Note Reporting
Bugs: (emacs)Bugs, for instructions how to do that.
The file `etc/PROBLEMS' in the Emacs distribution lists various
known problems with building and using Emacs on specific platforms;
type `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::
File: efaq, Node: Problems with very large files, Next: ^M in the shell buffer, Prev: Bugs and problems, Up: Bugs and problems
Does Emacs have problems with files larger than 8 megabytes?
============================================================
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. Leonard N. Zubkoff <lnz@lucid.com>
suggests putting the following two lines in `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):
#define VALBITS 26
#define GCTYPEBITS 5
This method may result in "ILLEGAL DATATYPE" and other random errors on
some machines.
David Gillespie <daveg@csvax.cs.caltech.edu> 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.
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 "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.
File: efaq, Node: ^M in the shell buffer, Next: Shell process exits abnormally, Prev: Problems with very large files, Up: Bugs and problems
How do I get rid of `^M' or echoed commands in my shell buffer?
===============================================================
Try typing `M-x shell-strip-ctrl-m <RET>' while in `shell-mode' to
make them go away. If that doesn't work, you have several options:
For `tcsh', put this in your `.cshrc' (or `.tcshrc') file:
if ($?EMACS) then
if ("$EMACS" == t) then
if ($?tcsh) unset edit
stty nl
endif
endif
Or put this in your `.emacs_tcsh' file:
unset edit
stty nl
Alternatively, use `csh' in your shell buffers instead of `tcsh'.
One way is:
(setq explicit-shell-file-name "/bin/csh")
and another is to do this in your `.cshrc' (or `.tcshrc') file:
setenv ESHELL /bin/csh
(You must start Emacs over again with the environment variable properly
set for this to take effect.)
You can also set the `ESHELL' environment variable in Emacs Lisp
with the following Lisp form,
(setenv "ESHELL" "/bin/csh")
The above solutions try to prevent the shell from producing the `^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 `.emacs' init file:
(add-hook 'comint-output-filter-functions 'shell-strip-ctrl-m)
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:
stty -icrnl -onlcr -echo susp ^Z
File: efaq, Node: Shell process exits abnormally, Next: Problems with Shell Mode on MS-Windows, Prev: ^M in the shell buffer, Up: Bugs and problems
Why do I get "Process shell exited abnormally with code 1"?
===========================================================
The most likely reason for this message is that the `env' program is
not properly installed. Compile this program for your architecture,
and install it with `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 `exec-directory' by typing
`C-h v exec-directory <RET>'.)
You should also check for other programs named `env' in your path
(e.g., SunOS has a program named `/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 `make clean' command will remove `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 `PROBLEMS' (in the `etc' subdirectory of the top-level
directory when you unpack the Emacs source) for other possible causes
of this message.
File: efaq, Node: Problems with Shell Mode on MS-Windows, Next: Termcap/Terminfo entries for Emacs, Prev: Shell process exits abnormally, Up: Bugs and problems
Why do I get an error message when I try to run `M-x shell'?
============================================================
On MS-Windows, this might happen because Emacs tries to look for the
shell in a wrong place. The default file name `/bin/sh' is usually
incorrect for non-Unix systems. If you know where your shell
executable is, set the variable `explicit-shell-file-name' in your
`.emacs' file to point to its full file name, like this:
(setq explicit-shell-file-name "d:/shells/bash.exe")
If you don't know what shell does Emacs use, try the `M-!' command;
if that works, put the following line into your `.emacs':
(setq explicit-shell-file-name shell-file-name)
Some people have trouble with Shell Mode because of intrusive
antivirus software; disabling the resident antivirus program solves the
problems in those cases.
File: efaq, Node: Termcap/Terminfo entries for Emacs, Next: Spontaneous entry into isearch-mode, Prev: Problems with Shell Mode on MS-Windows, Up: Bugs and problems
Where is the termcap/terminfo entry for terminal type "emacs"?
==============================================================
The termcap entry for terminal type `emacs' is ordinarily put in the
`TERMCAP' environment variable of subshells. It may help in certain
situations (e.g., using rlogin from shell buffer) to add an entry for
`emacs' to the system-wide termcap file. Here is a correct termcap
entry for `emacs':
emacs:tc=unknown:
To make a terminfo entry for `emacs', use `tic' or `captoinfo'. You
need to generate `/usr/lib/terminfo/e/emacs'. It may work to simply
copy `/usr/lib/terminfo/d/dumb' to `/usr/lib/terminfo/e/emacs'.
Having a termcap/terminfo entry will not enable the use of full
screen programs in shell buffers. Use `M-x terminal-emulator' for that
instead.
A workaround to the problem of missing termcap/terminfo entries is to
change terminal type `emacs' to type `dumb' or `unknown' in your shell
start up file. `csh' users could put this in their `.cshrc' files:
if ("$term" == emacs) set term=dumb