This is ../info/emacs, produced by makeinfo version 4.0f from
emacs.texi.
This is the Fourteenth edition of the `GNU Emacs Manual', updated
for Emacs version 21.2.
INFO-DIR-SECTION Emacs
START-INFO-DIR-ENTRY
* Emacs: (emacs). The extensible self-documenting text editor.
END-INFO-DIR-ENTRY
Published by the Free Software Foundation 59 Temple Place, Suite 330
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File: emacs, Node: Registers, Next: Display, Prev: Rectangles, Up: Top
Registers
*********
Emacs "registers" are compartments where you can save text,
rectangles, positions, and other things for later use. Once you save
text or a rectangle in a register, you can copy it into the buffer
once, or many times; you can move point to a position saved in a
register once, or many times.
Each register has a name, which consists of a single character. A
register can store a piece of text, a rectangle, a position, a window
configuration, or a file name, but only one thing at any given time.
Whatever you store in a register remains there until you store
something else in that register. To see what a register R contains,
use `M-x view-register'.
`M-x view-register <RET> R'
Display a description of what register R contains.
* Menu:
* Position: RegPos. Saving positions in registers.
* Text: RegText. Saving text in registers.
* Rectangle: RegRect. Saving rectangles in registers.
* Configurations: RegConfig. Saving window configurations in registers.
* Files: RegFiles. File names in registers.
* Numbers: RegNumbers. Numbers in registers.
* Bookmarks:: Bookmarks are like registers, but persistent.
File: emacs, Node: RegPos, Next: RegText, Up: Registers
Saving Positions in Registers
=============================
Saving a position records a place in a buffer so that you can move
back there later. Moving to a saved position switches to that buffer
and moves point to that place in it.
`C-x r <SPC> R'
Save position of point in register R (`point-to-register').
`C-x r j R'
Jump to the position saved in register R (`jump-to-register').
To save the current position of point in a register, choose a name R
and type `C-x r <SPC> R'. The register R retains the position thus
saved until you store something else in that register.
The command `C-x r j R' moves point to the position recorded in
register R. The register is not affected; it continues to hold the
same position. You can jump to the saved position any number of times.
If you use `C-x r j' to go to a saved position, but the buffer it
was saved from has been killed, `C-x r j' tries to create the buffer
again by visiting the same file. Of course, this works only for buffers
that were visiting files.
File: emacs, Node: RegText, Next: RegRect, Prev: RegPos, Up: Registers
Saving Text in Registers
========================
When you want to insert a copy of the same piece of text several
times, it may be inconvenient to yank it from the kill ring, since each
subsequent kill moves that entry further down the ring. An alternative
is to store the text in a register and later retrieve it.
`C-x r s R'
Copy region into register R (`copy-to-register').
`C-x r i R'
Insert text from register R (`insert-register').
`M-x append-to-register <RET> R'
Append region to text in register R.
`M-x prepend-to-register <RET> R'
Prepend region to text in register R.
`C-x r s R' stores a copy of the text of the region into the
register named R. `C-u C-x r s R', the same command with a numeric
argument, deletes the text from the buffer as well; you can think of
this as "moving" the region text into the register.
`M-x append-to-register <RET> R' appends the copy of the text in the
region to the text already stored in the register named R. If invoked
with a numeric argument, it deletes the region after appending it to
the register. A similar command `prepend-to-register' works the same,
except that it _prepends_ the region text to the text in the register,
rather than _appending_ it.
`C-x r i R' inserts in the buffer the text from register R.
Normally it leaves point before the text and places the mark after, but
with a numeric argument (`C-u') it puts point after the text and the
mark before.
File: emacs, Node: RegRect, Next: RegConfig, Prev: RegText, Up: Registers
Saving Rectangles in Registers
==============================
A register can contain a rectangle instead of linear text. The
rectangle is represented as a list of strings. *Note Rectangles::, for
basic information on how to specify a rectangle in the buffer.
`C-x r r R'
Copy the region-rectangle into register R
(`copy-rectangle-to-register'). With numeric argument, delete it
as well.
`C-x r i R'
Insert the rectangle stored in register R (if it contains a
rectangle) (`insert-register').
The `C-x r i R' command inserts a text string if the register
contains one, and inserts a rectangle if the register contains one.
See also the command `sort-columns', which you can think of as
sorting a rectangle. *Note Sorting::.
File: emacs, Node: RegConfig, Next: RegFiles, Prev: RegRect, Up: Registers
Saving Window Configurations in Registers
=========================================
You can save the window configuration of the selected frame in a
register, or even the configuration of all windows in all frames, and
restore the configuration later.
`C-x r w R'
Save the state of the selected frame's windows in register R
(`window-configuration-to-register').
`C-x r f R'
Save the state of all frames, including all their windows, in
register R (`frame-configuration-to-register').
Use `C-x r j R' to restore a window or frame configuration. This is
the same command used to restore a cursor position. When you restore a
frame configuration, any existing frames not included in the
configuration become invisible. If you wish to delete these frames
instead, use `C-u C-x r j R'.
File: emacs, Node: RegNumbers, Next: Bookmarks, Prev: RegFiles, Up: Registers
Keeping Numbers in Registers
============================
There are commands to store a number in a register, to insert the
number in the buffer in decimal, and to increment it. These commands
can be useful in keyboard macros (*note Keyboard Macros::).
`C-u NUMBER C-x r n R'
Store NUMBER into register R (`number-to-register').
`C-u NUMBER C-x r + R'
Increment the number in register R by NUMBER
(`increment-register').
`C-x r g R'
Insert the number from register R into the buffer.
`C-x r g' is the same command used to insert any other sort of
register contents into the buffer. `C-x r +' with no numeric argument
increments the register value by 1; `C-x r n' with no numeric argument
stores zero in the register.
File: emacs, Node: RegFiles, Next: RegNumbers, Prev: RegConfig, Up: Registers
Keeping File Names in Registers
===============================
If you visit certain file names frequently, you can visit them more
conveniently if you put their names in registers. Here's the Lisp code
used to put a file name in a register:
(set-register ?R '(file . NAME))
For example,
(set-register ?z '(file . "/gd/gnu/emacs/19.0/src/ChangeLog"))
puts the file name shown in register `z'.
To visit the file whose name is in register R, type `C-x r j R'.
(This is the same command used to jump to a position or restore a frame
configuration.)
File: emacs, Node: Bookmarks, Prev: RegNumbers, Up: Registers
Bookmarks
=========
"Bookmarks" are somewhat like registers in that they record
positions you can jump to. Unlike registers, they have long names, and
they persist automatically from one Emacs session to the next. The
prototypical use of bookmarks is to record "where you were reading" in
various files.
`C-x r m <RET>'
Set the bookmark for the visited file, at point.
`C-x r m BOOKMARK <RET>'
Set the bookmark named BOOKMARK at point (`bookmark-set').
`C-x r b BOOKMARK <RET>'
Jump to the bookmark named BOOKMARK (`bookmark-jump').
`C-x r l'
List all bookmarks (`list-bookmarks').
`M-x bookmark-save'
Save all the current bookmark values in the default bookmark file.
The prototypical use for bookmarks is to record one current position
in each of several files. So the command `C-x r m', which sets a
bookmark, uses the visited file name as the default for the bookmark
name. If you name each bookmark after the file it points to, then you
can conveniently revisit any of those files with `C-x r b', and move to
the position of the bookmark at the same time.
To display a list of all your bookmarks in a separate buffer, type
`C-x r l' (`list-bookmarks'). If you switch to that buffer, you can
use it to edit your bookmark definitions or annotate the bookmarks.
Type `C-h m' in the bookmark buffer for more information about its
special editing commands.
When you kill Emacs, Emacs offers to save your bookmark values in
your default bookmark file, `~/.emacs.bmk', if you have changed any
bookmark values. You can also save the bookmarks at any time with the
`M-x bookmark-save' command. The bookmark commands load your default
bookmark file automatically. This saving and loading is how bookmarks
persist from one Emacs session to the next.
If you set the variable `bookmark-save-flag' to 1, then each command
that sets a bookmark will also save your bookmarks; this way, you don't
lose any bookmark values even if Emacs crashes. (The value, if a
number, says how many bookmark modifications should go by between
saving.)
Bookmark position values are saved with surrounding context, so that
`bookmark-jump' can find the proper position even if the file is
modified slightly. The variable `bookmark-search-size' says how many
characters of context to record on each side of the bookmark's position.
Here are some additional commands for working with bookmarks:
`M-x bookmark-load <RET> FILENAME <RET>'
Load a file named FILENAME that contains a list of bookmark
values. You can use this command, as well as `bookmark-write', to
work with other files of bookmark values in addition to your
default bookmark file.
`M-x bookmark-write <RET> FILENAME <RET>'
Save all the current bookmark values in the file FILENAME.
`M-x bookmark-delete <RET> BOOKMARK <RET>'
Delete the bookmark named BOOKMARK.
`M-x bookmark-insert-location <RET> BOOKMARK <RET>'
Insert in the buffer the name of the file that bookmark BOOKMARK
points to.
`M-x bookmark-insert <RET> BOOKMARK <RET>'
Insert in the buffer the _contents_ of the file that bookmark
BOOKMARK points to.
File: emacs, Node: Display, Next: Search, Prev: Registers, Up: Top
Controlling the Display
***********************
Since only part of a large buffer fits in the window, Emacs tries to
show a part that is likely to be interesting. Display-control commands
allow you to specify which part of the text you want to see, and how to
display it.
* Menu:
* Faces:: How to change the display style using faces.
* Font Lock:: Minor mode for syntactic highlighting using faces.
* Highlight Changes:: Using colors to show where you changed the buffer.
* Highlight Interactively:: Tell Emacs what text to highlight.
* Trailing Whitespace:: Showing possibly-spurious trailing whitespace.
* Scrolling:: Moving text up and down in a window.
* Horizontal Scrolling:: Moving text left and right in a window.
* Follow Mode:: Follow mode lets two windows scroll as one.
* Selective Display:: Hiding lines with lots of indentation.
* Optional Mode Line:: Optional mode line display features.
* Text Display:: How text characters are normally displayed.
* Display Custom:: Information on variables for customizing display.
* Cursor Display:: Features for displaying the cursor.
File: emacs, Node: Faces, Next: Font Lock, Up: Display
Using Multiple Typefaces
========================
When using Emacs with a window system, you can set up multiple
styles of displaying characters. Each style is called a "face". Each
face can specify various attributes, such as the height, weight and
slant of the characters, the foreground and background color, and
underlining. But it does not have to specify all of them.
Emacs on a character terminal supports only part of face attributes.
Which attributes are supported depends on your display type, but many
displays support inverse video, bold, and underline attributes, and
some support colors.
Features which rely on text in multiple faces (such as Font Lock
mode) will also work on non-windowed terminals that can display more
than one face, whether by colors or underlining and emboldening. This
includes the console on GNU/Linux, an `xterm' which supports colors, the
MS-DOS display (*note MS-DOS::), and the MS-Windows version invoked with
the `-nw' option. Emacs determines automatically whether the terminal
has this capability.
You control the appearance of a part of the text in the buffer by
specifying the face or faces to use for it. The style of display used
for any given character is determined by combining the attributes of
all the applicable faces specified for that character. Any attribute
that isn't specified by these faces is taken from the `default' face,
whose attributes reflect the default settings of the frame itself.
Enriched mode, the mode for editing formatted text, includes several
commands and menus for specifying faces for text in the buffer. *Note
Format Faces::, for how to specify the font for text in the buffer.
*Note Format Colors::, for how to specify the foreground and background
color.
To alter the appearance of a face, use the customization buffer.
*Note Face Customization::. You can also use X resources to specify
attributes of particular faces (*note Resources X::). Alternatively,
you can change the foreground and background colors of a specific face
with `M-x set-face-foreground' and `M-x set-face-background'. These
commands prompt in the minibuffer for a face name and a color name,
with completion, and then set that face to use the specified color.
Changing the colors of the `default' face also changes the foreground
and background colors on all frames, both existing and those to be
created in the future. (You can also set foreground and background
colors for the current frame only; see *Note Frame Parameters::.)
Emacs 21 can correctly display variable-width fonts, but Emacs
commands that calculate width and indentation do not know how to
calculate variable widths. This can sometimes lead to incorrect
results when you use variable-width fonts. In particular, indentation
commands can give inconsistent results, so we recommend you avoid
variable-width fonts for editing program source code. Filling will
sometimes make lines too long or too short. We plan to address these
issues in future Emacs versions.
To see what faces are currently defined, and what they look like,
type `M-x list-faces-display'. It's possible for a given face to look
different in different frames; this command shows the appearance in the
frame in which you type it. Here's a list of the standard defined
faces:
`default'
This face is used for ordinary text that doesn't specify any other
face.
`mode-line'
This face is used for mode lines. By default, it's drawn with
shadows for a "raised" effect on window systems, and drawn as the
inverse of the default face on non-windowed terminals. *Note
Display Custom::.
`header-line'
Similar to `mode-line' for a window's header line. Most modes
don't use the header line, but the Info mode does.
`highlight'
This face is used for highlighting portions of text, in various
modes. For example, mouse-sensitive text is highlighted using
this face.
`isearch'
This face is used for highlighting Isearch matches.
`isearch-lazy-highlight-face'
This face is used for lazy highlighting of Isearch matches other
than the current one.
`region'
This face is used for displaying a selected region (when Transient
Mark mode is enabled--see below).
`secondary-selection'
This face is used for displaying a secondary X selection (*note
Secondary Selection::).
`bold'
This face uses a bold variant of the default font, if it has one.
`italic'
This face uses an italic variant of the default font, if it has
one.
`bold-italic'
This face uses a bold italic variant of the default font, if it
has one.
`underline'
This face underlines text.
`fixed-pitch'
The basic fixed-pitch face.
`fringe'
The face for the fringes to the left and right of windows on
graphic displays. (The fringes are the narrow portions of the
Emacs frame between the text area and the window's right and left
borders.)
`scroll-bar'
This face determines the visual appearance of the scroll bar.
`border'
This face determines the color of the frame border.
`cursor'
This face determines the color of the cursor.
`mouse'
This face determines the color of the mouse pointer.
`tool-bar'
This is the basic tool-bar face. No text appears in the tool bar,
but the colors of this face affect the appearance of tool bar
icons.
`tooltip'
This face is used for tooltips.
`menu'
This face determines the colors and font of Emacs's menus.
Setting the font of LessTif/Motif menus is currently not
supported; attempts to set the font are ignored in this case.
`trailing-whitespace'
The face for highlighting trailing whitespace when
`show-trailing-whitespace' is non-nil; see *Note Trailing
Whitespace::.
`variable-pitch'
The basic variable-pitch face.
When Transient Mark mode is enabled, the text of the region is
highlighted when the mark is active. This uses the face named
`region'; you can control the style of highlighting by changing the
style of this face (*note Face Customization::). *Note Transient
Mark::, for more information about Transient Mark mode and activation
and deactivation of the mark.
One easy way to use faces is to turn on Font Lock mode. This minor
mode, which is always local to a particular buffer, arranges to choose
faces according to the syntax of the text you are editing. It can
recognize comments and strings in most languages; in several languages,
it can also recognize and properly highlight various other important
constructs. *Note Font Lock::, for more information about Font Lock
mode and syntactic highlighting.
You can print out the buffer with the highlighting that appears on
your screen using the command `ps-print-buffer-with-faces'. *Note
PostScript::.
File: emacs, Node: Font Lock, Next: Highlight Changes, Prev: Faces, Up: Display
Font Lock mode
==============
Font Lock mode is a minor mode, always local to a particular buffer,
which highlights (or "fontifies") using various faces according to the
syntax of the text you are editing. It can recognize comments and
strings in most languages; in several languages, it can also recognize
and properly highlight various other important constructs--for example,
names of functions being defined or reserved keywords.
The command `M-x font-lock-mode' turns Font Lock mode on or off
according to the argument, and toggles the mode when it has no argument.
The function `turn-on-font-lock' unconditionally enables Font Lock
mode. This is useful in mode-hook functions. For example, to enable
Font Lock mode whenever you edit a C file, you can do this:
(add-hook 'c-mode-hook 'turn-on-font-lock)
To turn on Font Lock mode automatically in all modes which support
it, customize the user option `global-font-lock-mode' or use the
function `global-font-lock-mode' in your `.emacs' file, like this:
(global-font-lock-mode 1)
Font Lock mode uses several specifically named faces to do its job,
including `font-lock-string-face', `font-lock-comment-face', and
others. The easiest way to find them all is to use completion on the
face name in `set-face-foreground'.
To change the colors or the fonts used by Font Lock mode to fontify
different parts of text, just change these faces. There are two ways
to do it:
* Invoke `M-x set-face-foreground' or `M-x set-face-background' to
change the colors of a particular face used by Font Lock. *Note
Faces::. The command `M-x list-faces-display' displays all the
faces currently known to Emacs, including those used by Font Lock.
* Customize the faces interactively with `M-x customize-face', as
described in *Note Face Customization::.
To get the full benefit of Font Lock mode, you need to choose a
default font which has bold, italic, and bold-italic variants; or else
you need to have a color or gray-scale screen.
The variable `font-lock-maximum-decoration' specifies the preferred
level of fontification, for modes that provide multiple levels. Level
1 is the least amount of fontification; some modes support levels as
high as 3. The normal default is "as high as possible." You can
specify an integer, which applies to all modes, or you can specify
different numbers for particular major modes; for example, to use level
1 for C/C++ modes, and the default level otherwise, use this:
(setq font-lock-maximum-decoration
'((c-mode . 1) (c++-mode . 1)))
Fontification can be too slow for large buffers, so you can suppress
it. The variable `font-lock-maximum-size' specifies a buffer size,
beyond which buffer fontification is suppressed.
Comment and string fontification (or "syntactic" fontification)
relies on analysis of the syntactic structure of the buffer text. For
the sake of speed, some modes, including C mode and Lisp mode, rely on
a special convention: an open-parenthesis or open-brace in the leftmost
column always defines the beginning of a defun, and is thus always
outside any string or comment. (*Note Left Margin Paren::.) If you
don't follow this convention, Font Lock mode can misfontify the text
that follows an open-parenthesis or open-brace in the leftmost column
that is inside a string or comment.
The variable `font-lock-beginning-of-syntax-function' (always
buffer-local) specifies how Font Lock mode can find a position
guaranteed to be outside any comment or string. In modes which use the
leftmost column parenthesis convention, the default value of the
variable is `beginning-of-defun'--that tells Font Lock mode to use the
convention. If you set this variable to `nil', Font Lock no longer
relies on the convention. This avoids incorrect results, but the price
is that, in some cases, fontification for a changed text must rescan
buffer text from the beginning of the buffer. This can considerably
slow down redisplay while scrolling, particularly if you are close to
the end of a large buffer.
Font Lock highlighting patterns already exist for many modes, but you
may want to fontify additional patterns. You can use the function
`font-lock-add-keywords', to add your own highlighting patterns for a
particular mode. For example, to highlight `FIXME:' words in C
comments, use this:
(font-lock-add-keywords
'c-mode
'(("\\<\\(FIXME\\):" 1 font-lock-warning-face t)))
To remove keywords from the font-lock highlighting patterns, use the
function `font-lock-remove-keywords'.
File: emacs, Node: Highlight Changes, Next: Highlight Interactively, Prev: Font Lock, Up: Display
Highlight Changes Mode
======================
Use `M-x highlight-changes-mode' to enable a minor mode that uses
faces (colors, typically) to indicate which parts of the buffer were
changed most recently.
File: emacs, Node: Highlight Interactively, Next: Trailing Whitespace, Prev: Highlight Changes, Up: Display
Interactive Highlighting by Matching
====================================
It is sometimes useful to highlight the strings that match a certain
regular expression. For example, you might wish to see all the
references to a certain variable in a program source file, or highlight
certain parts in a voluminous output of some program, or make certain
cliches stand out in an article.
Use the `M-x hi-lock-mode' command to turn on a minor mode that
allows you to specify regular expressions of the text to be
highlighted. Hi-lock mode works like Font Lock (*note Font Lock::),
except that it lets you specify explicitly what parts of text to
highlight. You control Hi-lock mode with these commands:
`C-x w h REGEXP <RET> FACE <RET>'
Highlight text that matches REGEXP using face FACE
(`highlight-regexp'). By using this command more than once, you
can highlight various parts of the text in different ways.
`C-x w r REGEXP <RET>'
Unhighlight REGEXP (`unhighlight-regexp'). You must enter one of
the regular expressions currently specified for highlighting.
(You can use completion, or choose from a menu, to enter one of
them conveniently.)
`C-x w l REGEXP <RET> FACE <RET>'
Highlight entire lines containing a match for REGEXP, using face
FACE (`highlight-lines-matching-regexp').
`C-x w b'
Insert all the current highlighting regexp/face pairs into the
buffer at point, with comment delimiters to prevent them from
changing your program. This key binding runs the
`hi-lock-write-interactive-patterns' command.
These patterns will be read the next time you visit the file while
Hi-lock mode is enabled, or whenever you use the `M-x
hi-lock-find-patterns' command.
`C-x w i'
Re-read regexp/face pairs in the current buffer
(`hi-lock-write-interactive-patterns'). The list of pairs is
found no matter where in the buffer it may be.
This command does nothing if the major mode is a member of the list
`hi-lock-exclude-modes'.
File: emacs, Node: Trailing Whitespace, Next: Scrolling, Prev: Highlight Interactively, Up: Display
Trailing Whitespace
===================
It is easy to leave unnecessary spaces at the end of a line without
realizing it. In most cases, this "trailing whitespace" has no effect,
but there are special circumstances where it matters.
You can make trailing whitespace visible on the screen by setting the
buffer-local variable `show-trailing-whitespace' to `t'. Then Emacs
displays trailing whitespace in the face `trailing-whitespace'.
Trailing whitespace is defined as spaces or tabs at the end of a
line. But trailing whitespace is not displayed specially if point is
at the end of the line containing the whitespace. (Doing that looks
ugly while you are typing in new text, and the location of point is
enough in that case to show you that the spaces are present.)
To delete all trailing whitespace within the current buffer's
restriction (*note Narrowing::), type `M-x delete-trailing-whitespace
<RET>'. (This command does not remove the form-feed characters.)
Emacs can indicate empty lines at the end of the buffer with a
special bitmap on the left fringe of the window. To enable this
feature, set the buffer-local variable `indicate-empty-lines' to a
non-`nil' value. The default value of this variable is controlled by
the variable `default-indicate-empty-lines'; by setting that variable,
you can enable or disable this feature for all new buffers.
File: emacs, Node: Scrolling, Next: Horizontal Scrolling, Prev: Trailing Whitespace, Up: Display
Scrolling
=========
If a buffer contains text that is too large to fit entirely within a
window that is displaying the buffer, Emacs shows a contiguous portion
of the text. The portion shown always contains point.
"Scrolling" means moving text up or down in the window so that
different parts of the text are visible. Scrolling forward means that
text moves up, and new text appears at the bottom. Scrolling backward
moves text down and new text appears at the top.
Scrolling happens automatically if you move point past the bottom or
top of the window. You can also explicitly request scrolling with the
commands in this section.
`C-l'
Clear screen and redisplay, scrolling the selected window to center
point vertically within it (`recenter').
`C-v'
Scroll forward (a windowful or a specified number of lines)
(`scroll-up').
`<NEXT>'
`<PAGEDOWN>'
Likewise, scroll forward.
`M-v'
Scroll backward (`scroll-down').
`<PRIOR>'
`<PAGEUP>'
Likewise, scroll backward.
`ARG C-l'
Scroll so point is on line ARG (`recenter').
`C-M-l'
Scroll heuristically to bring useful information onto the screen
(`reposition-window').
The most basic scrolling command is `C-l' (`recenter') with no
argument. It clears the entire screen and redisplays all windows. In
addition, it scrolls the selected window so that point is halfway down
from the top of the window.
To read the buffer a windowful at a time, use `C-v' (`scroll-up')
with no argument. This scrolls forward by nearly the whole window
height. The effect is to take the two lines at the bottom of the
window and put them at the top, followed by nearly a whole windowful of
lines that were not previously visible. If point was in the text that
scrolled off the top, it ends up at the new top of the window.
`M-v' (`scroll-down') with no argument scrolls backward in a similar
way, also with overlap. The number of lines of overlap across a `C-v'
or `M-v' is controlled by the variable `next-screen-context-lines'; by
default, it is 2. The function keys <NEXT> and <PRIOR>, or <PAGEDOWN>
and <PAGEUP>, are equivalent to `C-v' and `M-v'.
The commands `C-v' and `M-v' with a numeric argument scroll the text
in the selected window up or down a few lines. `C-v' with an argument
moves the text and point up, together, that many lines; it brings the
same number of new lines into view at the bottom of the window. `M-v'
with numeric argument scrolls the text downward, bringing that many new
lines into view at the top of the window. `C-v' with a negative
argument is like `M-v' and vice versa.
The names of scroll commands are based on the direction that the
text moves in the window. Thus, the command to scroll forward is
called `scroll-up' because it moves the text upward on the screen. The
keys <PAGEDOWN> and <PAGEUP> derive their names and customary meanings
from a different convention that developed elsewhere; hence the strange
result that <PAGEDOWN> runs `scroll-up'.
Some users like the full-screen scroll commands to keep point at the
same screen line. To enable this behavior, set the variable
`scroll-preserve-screen-position' to a non-`nil' value. This mode is
convenient for browsing through a file by scrolling by screenfuls; if
you come back to the screen where you started, point goes back to the
line where it started. However, this mode is inconvenient when you
move to the next screen in order to move point to the text there.
Another way to do scrolling is with `C-l' with a numeric argument.
`C-l' does not clear the screen when given an argument; it only scrolls
the selected window. With a positive argument N, it repositions text
to put point N lines down from the top. An argument of zero puts point
on the very top line. Point does not move with respect to the text;
rather, the text and point move rigidly on the screen. `C-l' with a
negative argument puts point that many lines from the bottom of the
window. For example, `C-u - 1 C-l' puts point on the bottom line, and
`C-u - 5 C-l' puts it five lines from the bottom. `C-u C-l' scrolls to
put point at the center (vertically) of the selected window.
The `C-M-l' command (`reposition-window') scrolls the current window
heuristically in a way designed to get useful information onto the
screen. For example, in a Lisp file, this command tries to get the
entire current defun onto the screen if possible.
Scrolling happens automatically when point moves out of the visible
portion of the text. Normally, automatic scrolling centers point
vertically within the window. However, if you set
`scroll-conservatively' to a small number N, then if you move point
just a little off the screen--less than N lines--then Emacs scrolls the
text just far enough to bring point back on screen. By default,
`scroll-conservatively' is 0.
When the window does scroll by a longer distance, you can control
how aggressively it scrolls, by setting the variables
`scroll-up-aggressively' and `scroll-down-aggressively'. The value of
`scroll-up-aggressively' should be either `nil', or a fraction F
between 0 and 1. A fraction specifies where on the screen to put point
when scrolling upward. More precisely, when a window scrolls up
because point is above the window start, the new start position is
chosen to put point F part of the window height from the top. The
larger F, the more aggressive the scrolling.
`nil', which is the default, scrolls to put point at the center. So
it is equivalent to .5.
Likewise, `scroll-down-aggressively' is used for scrolling down.
The value, F, specifies how far point should be placed from the bottom
of the window; thus, as with `scroll-up-aggressively', a larger value
is more aggressive.
The variable `scroll-margin' restricts how close point can come to
the top or bottom of a window. Its value is a number of screen lines;
if point comes within that many lines of the top or bottom of the
window, Emacs recenters the window. By default, `scroll-margin' is 0.
File: emacs, Node: Horizontal Scrolling, Next: Follow Mode, Prev: Scrolling, Up: Display
Horizontal Scrolling
====================
"Horizontal scrolling" means shifting all the lines sideways within
a window--so that some of the text near the left margin is not
displayed at all. Emacs does this automatically in any window that
uses line truncation rather than continuation: whenever point moves off
the left or right edge of the screen, Emacs scrolls the buffer
horizontally to make point visible.
When a window has been scrolled horizontally, text lines are
truncated rather than continued (*note Continuation Lines::), with a `$'
appearing in the first column when there is text truncated to the left,
and in the last column when there is text truncated to the right.
You can use these commands to do explicit horizontal scrolling.
`C-x <'
Scroll text in current window to the left (`scroll-left').
`C-x >'
Scroll to the right (`scroll-right').
The command `C-x <' (`scroll-left') scrolls the selected window to
the left by N columns with argument N. This moves part of the
beginning of each line off the left edge of the window. With no
argument, it scrolls by almost the full width of the window (two
columns less, to be precise).
`C-x >' (`scroll-right') scrolls similarly to the right. The window
cannot be scrolled any farther to the right once it is displayed
normally (with each line starting at the window's left margin);
attempting to do so has no effect. This means that you don't have to
calculate the argument precisely for `C-x >'; any sufficiently large
argument will restore the normal display.
If you scroll a window horizontally by hand, that sets a lower bound
for automatic horizontal scrolling. Automatic scrolling will continue
to scroll the window, but never farther to the right than the amount
you previously set by `scroll-left'.
To disable automatic horizontal scrolling, set the variable
`automatic-hscrolling' to `nil'.
File: emacs, Node: Follow Mode, Next: Selective Display, Prev: Horizontal Scrolling, Up: Display
Follow Mode
===========
"Follow mode" is a minor mode that makes two windows showing the
same buffer scroll as one tall "virtual window." To use Follow mode,
go to a frame with just one window, split it into two side-by-side
windows using `C-x 3', and then type `M-x follow-mode'. From then on,
you can edit the buffer in either of the two windows, or scroll either
one; the other window follows it.
In Follow mode, if you move point outside the portion visible in one
window and into the portion visible in the other window, that selects
the other window--again, treating the two as if they were parts of one
large window.
To turn off Follow mode, type `M-x follow-mode' a second time.
File: emacs, Node: Selective Display, Next: Optional Mode Line, Prev: Follow Mode, Up: Display
Selective Display
=================
Emacs has the ability to hide lines indented more than a certain
number of columns (you specify how many columns). You can use this to
get an overview of a part of a program.
To hide lines, type `C-x $' (`set-selective-display') with a numeric
argument N. Then lines with at least N columns of indentation
disappear from the screen. The only indication of their presence is
that three dots (`...') appear at the end of each visible line that is
followed by one or more hidden ones.
The commands `C-n' and `C-p' move across the hidden lines as if they
were not there.
The hidden lines are still present in the buffer, and most editing
commands see them as usual, so you may find point in the middle of the
hidden text. When this happens, the cursor appears at the end of the
previous line, after the three dots. If point is at the end of the
visible line, before the newline that ends it, the cursor appears before
the three dots.
To make all lines visible again, type `C-x $' with no argument.
If you set the variable `selective-display-ellipses' to `nil', the
three dots do not appear at the end of a line that precedes hidden
lines. Then there is no visible indication of the hidden lines. This
variable becomes local automatically when set.
File: emacs, Node: Optional Mode Line, Next: Text Display, Prev: Selective Display, Up: Display
Optional Mode Line Features
===========================
The current line number of point appears in the mode line when Line
Number mode is enabled. Use the command `M-x line-number-mode' to turn
this mode on and off; normally it is on. The line number appears
before the buffer percentage POS, with the letter `L' to indicate what
it is. *Note Minor Modes::, for more information about minor modes and
about how to use this command.
If you have narrowed the buffer (*note Narrowing::), the displayed
line number is relative to the accessible portion of the buffer.
If the buffer is very large (larger than the value of
`line-number-display-limit'), then the line number doesn't appear.
Emacs doesn't compute the line number when the buffer is large, because
that would be too slow. Set it to `nil' to remove the limit.
Line-number computation can also be slow if the lines in the buffer
are too long. For this reason, Emacs normally doesn't display line
numbers if the average width, in characters, of lines near point is
larger than the value of the variable
`line-number-display-limit-width'. The default value is 200 characters.
You can also display the current column number by turning on Column
Number mode. It displays the current column number preceded by the
letter `C'. Type `M-x column-number-mode' to toggle this mode.
Emacs can optionally display the time and system load in all mode
lines. To enable this feature, type `M-x display-time' or customize
the option `display-time-mode'. The information added to the mode line
usually appears after the buffer name, before the mode names and their
parentheses. It looks like this:
HH:MMpm L.LL
Here HH and MM are the hour and minute, followed always by `am' or
`pm'. L.LL is the average number of running processes in the whole
system recently. (Some fields may be missing if your operating system
cannot support them.) If you prefer time display in 24-hour format,
set the variable `display-time-24hr-format' to `t'.
The word `Mail' appears after the load level if there is mail for
you that you have not read yet. On a graphical display you can use an
icon instead of `Mail' by customizing `display-time-use-mail-icon';
this may save some space on the mode line. You can customize
`display-time-mail-face' to make the mail indicator prominent.
By default, the mode line is drawn on graphics displays with
3D-style highlighting, like that of a button when it is not being
pressed. If you don't like this effect, you can disable the 3D
highlighting of the mode line, by customizing the attributes of the
`mode-line' face in your `.emacs' init file, like this:
(set-face-attribute 'mode-line nil :box nil)
Alternatively, you can turn off the box attribute in your `.Xdefaults'
file:
Emacs.mode-line.AttributeBox: off
File: emacs, Node: Text Display, Next: Display Custom, Prev: Optional Mode Line, Up: Display
How Text Is Displayed
=====================
ASCII printing characters (octal codes 040 through 0176) in Emacs
buffers are displayed with their graphics, as are non-ASCII multibyte
printing characters (octal codes above 0400).
Some ASCII control characters are displayed in special ways. The
newline character (octal code 012) is displayed by starting a new line.
The tab character (octal code 011) is displayed by moving to the next
tab stop column (normally every 8 columns).
Other ASCII control characters are normally displayed as a caret
(`^') followed by the non-control version of the character; thus,
control-A is displayed as `^A'.
Non-ASCII characters 0200 through 0237 (octal) are displayed with
octal escape sequences; thus, character code 0230 (octal) is displayed
as `\230'. The display of character codes 0240 through 0377 (octal)
may be either as escape sequences or as graphics. They do not normally
occur in multibyte buffers, but if they do, they are displayed as
Latin-1 graphics. In unibyte mode, if you enable European display they
are displayed using their graphics (assuming your terminal supports
them), otherwise as escape sequences. *Note Single-Byte Character
Support::.
File: emacs, Node: Display Custom, Next: Cursor Display, Prev: Text Display, Up: Display
Customization of Display
========================
This section contains information for customization only. Beginning
users should skip it.
The variable `mode-line-inverse-video' is an obsolete way of
controlling whether the mode line is displayed in inverse video; the
preferred way of doing this is to change the `mode-line' face. *Note
Mode Line::. However, if `mode-line-inverse-video' has a value of
`nil', then the `mode-line' face will be ignored, and mode-lines will
be drawn using the default text face. *Note Faces::.
If the variable `inverse-video' is non-`nil', Emacs attempts to
invert all the lines of the display from what they normally are.
If the variable `visible-bell' is non-`nil', Emacs attempts to make
the whole screen blink when it would normally make an audible bell
sound. This variable has no effect if your terminal does not have a way
to make the screen blink.
When you reenter Emacs after suspending, Emacs normally clears the
screen and redraws the entire display. On some terminals with more than
one page of memory, it is possible to arrange the termcap entry so that
the `ti' and `te' strings (output to the terminal when Emacs is entered
and exited, respectively) switch between pages of memory so as to use
one page for Emacs and another page for other output. Then you might
want to set the variable `no-redraw-on-reenter' non-`nil'; this tells
Emacs to assume, when resumed, that the screen page it is using still
contains what Emacs last wrote there.
The variable `echo-keystrokes' controls the echoing of
multi-character keys; its value is the number of seconds of pause
required to cause echoing to start, or zero meaning don't echo at all.
*Note Echo Area::.
If the variable `ctl-arrow' is `nil', all control characters in the
buffer are displayed with octal escape sequences, except for newline
and tab. Altering the value of `ctl-arrow' makes it local to the
current buffer; until that time, the default value is in effect. The
default is initially `t'. *Note Display Tables: (elisp)Display Tables.
Normally, a tab character in the buffer is displayed as whitespace
which extends to the next display tab stop position, and display tab
stops come at intervals equal to eight spaces. The number of spaces
per tab is controlled by the variable `tab-width', which is made local
by changing it, just like `ctl-arrow'. Note that how the tab character
in the buffer is displayed has nothing to do with the definition of
<TAB> as a command. The variable `tab-width' must have an integer
value between 1 and 1000, inclusive.
If the variable `truncate-lines' is non-`nil', then each line of
text gets just one screen line for display; if the text line is too
long, display shows only the part that fits. If `truncate-lines' is
`nil', then long text lines display as more than one screen line,
enough to show the whole text of the line. *Note Continuation Lines::.
Altering the value of `truncate-lines' makes it local to the current
buffer; until that time, the default value is in effect. The default
is initially `nil'.
If the variable `truncate-partial-width-windows' is non-`nil', it
forces truncation rather than continuation in any window less than the
full width of the screen or frame, regardless of the value of
`truncate-lines'. For information about side-by-side windows, see
*Note Split Window::. See also *Note Display: (elisp)Display.
The variable `baud-rate' holds the output speed of the terminal, as
far as Emacs knows. Setting this variable does not change the speed of
actual data transmission, but the value is used for calculations. On
terminals, it affects padding, and decisions about whether to scroll
part of the screen or redraw it instead. It also affects the behavior
of incremental search.
On window-systems, `baud-rate' is only used to determine how
frequently to look for pending input during display updating. A higher
value of `baud-rate' means that check for pending input will be done
less frequently.
You can customize the way any particular character code is displayed
by means of a display table. *Note Display Tables: (elisp)Display
Tables.
On a window system, Emacs can optionally display the mouse pointer
in a special shape to say that Emacs is busy. To turn this feature on
or off, customize the group `cursor'. You can also control the amount
of time Emacs must remain busy before the busy indicator is displayed,
by setting the variable `hourglass-delay'.
On some text-only terminals, bold face and inverse video together
result in text that is hard to read. Call the function
`tty-suppress-bold-inverse-default-colors' with a non-`nil' argument to
suppress the effect of bold-face in this case.
File: emacs, Node: Cursor Display, Prev: Display Custom, Up: Display
Displaying the Cursor
=====================
There are a number of ways to customize the display of the cursor.
`M-x hl-line-mode' enables or disables a minor mode which highlights
the line containing point. On window systems, the command `M-x
blink-cursor-mode' turns on or off the blinking of the cursor. (On
terminals, the terminal itself blinks the cursor, and Emacs has no
control over it.)
You can customize the cursor's color, and whether it blinks, using
the `cursor' Custom group (*note Easy Customization::).
When displaying on a window system, Emacs can optionally draw the
block cursor as wide as the character under the cursor--for example, if
the cursor is on a tab character, it would cover the full width
occupied by that tab character. To enable this feature, set the
variable `x-stretch-cursor' to a non-`nil' value.
Normally, the cursor in non-selected windows is shown as a hollow
box. To turn off cursor display in non-selected windows, customize the
option `cursor-in-non-selected-windows' to assign it a `nil' value.
File: emacs, Node: Search, Next: Fixit, Prev: Display, Up: Top
Searching and Replacement
*************************
Like other editors, Emacs has commands for searching for occurrences
of a string. The principal search command is unusual in that it is
"incremental"; it begins to search before you have finished typing the
search string. There are also nonincremental search commands more like
those of other editors.
Besides the usual `replace-string' command that finds all
occurrences of one string and replaces them with another, Emacs has a
more flexible replacement command called `query-replace', which asks
interactively which occurrences to replace.
* Menu:
* Incremental Search:: Search happens as you type the string.
* Nonincremental Search:: Specify entire string and then search.
* Word Search:: Search for sequence of words.
* Regexp Search:: Search for match for a regexp.
* Regexps:: Syntax of regular expressions.
* Search Case:: To ignore case while searching, or not.
* Replace:: Search, and replace some or all matches.
* Other Repeating Search:: Operating on all matches for some regexp.