27. Customization

This chapter talks about various topics relevant to adapting the behavior of Emacs in minor ways.

All kinds of customization affect only the particular Emacs job that you do them in. They are completely lost when you kill the Emacs job, and have no effect on other Emacs jobs you may run at the same time or later. The only way an Emacs job can affect anything outside of it is by writing a file; in particular, the only way to make a customization `permanent' is to put something in your init file or other appropriate file to do the customization in each session. See section 27.7 The Init File.

27.1 Minor Modes

Minor modes are common options which may be useful in many major modes, but which may need to be enabled or disabled independently of the major mode. (This may be because user preferences for the feature vary, or because the feature is sometimes more of a hindrance than an aid depending on the specific content of the buffer.) For example, Auto Fill mode is a minor mode in which SPC automatically breaks lines between words at the right margin as you type. Minor modes are independent of each other and of the selected major mode. Most minor modes inform you in the mode line when they are on; for example, `Fill' in the mode line means that Auto Fill mode is on.

Append -mode to the name of a minor mode to get the name of a command function that turns the mode on or off. Thus, the command to enable or disable Auto Fill mode is called M-x auto-fill-mode. These commands are usually invoked with M-x, but you can bind keys to them if you wish. With no argument, the function turns the mode on if it was off and off if it was on. This is called toggling. A positive argument always turns the mode on, and an explicit zero argument or a negative argument always turns it off.

Auto Fill mode allows you to enter filled text without breaking lines explicitly. Emacs inserts newlines as necessary to prevent lines from becoming too long. See section 20.6 Filling Text.

Filladapt mode is an extension of Auto Fill mode which recognizes line prefixes and automatically prepends them when automatically breaking lines. Filladapt mode is smart enough to recognize common idioms for bullets (e.g., leading isolated hyphens) and enumerated paragraphs, and insert appropriate leading whitespace (and omit the bullet!) It also does a good job of recognizing common quotation styles in email. Filladapt mode must be enabled in addition to Auto Fill mode. If Auto Fill mode is disabled, Filladapt mode will be inactivated, but the indicator will remain in the modeline.

Overwrite mode causes ordinary printing characters to replace existing text instead of moving it to the right. For example, if point is in front of the `B' in `FOOBAR', and you type a G in Overwrite mode, it changes to `FOOGAR', instead of `FOOGBAR'.

Pending Delete mode cause buffer insertions and deletions to replace the active region (with nothing, for deletions). This is the common behavior in most modern programs, but conflicts with the "lightweight selections" used in the X Window System.

Abbrev mode allows you to define abbreviations that automatically expand as you type them. For example, `amd' might expand to `abbrev mode'. See section 23. Abbrevs, for full information.

27.2 Behaviors

Behaviors are an alternative interface to minor modes. The toggle interface emphasizes the case-specific nature of a minor mode: use it with this major mode but not in those buffers. However, this is inconvenient for behavior that depends on user preference. For example, someone who discovers filladapt and really likes it must toggle it separately in each buffer. On the other hand, after trying it for a while she might like to disable it everywhere, having decided it doesn't work very well for her.

Use of mode hooks will invoke the minor mode automatically in the future, but this is inconvenient (you must switch tasks to editing the init file) and doesn't help with existing buffers in the session. The behavior interface addresses this problem. The command enable-behavior prompts (with completion) for a registered behavior (denoted by a symbol), and enables it. Conversely, disable-behavior prompts for a behavior, and disables it.

27.3 Variables

A variable is a Lisp symbol which has a value. Variable names can contain any characters, but by convention they are words separated by hyphens. A variable can also have a documentation string, which describes what kind of value it should have and how the value will be used.

Lisp allows any variable to have any kind of value, but most variables that Emacs uses require a value of a certain type. Often the value has to be a string or a number. Sometimes we say that a certain feature is turned on if a variable is "non-nil," meaning that if the variable's value is nil, the feature is off, but the feature is on for any other value. The conventional value to turn on the feature--since you have to pick one particular value when you set the variable--is t.

Emacs uses many Lisp variables for internal recordkeeping, as any Lisp program must, but the most interesting variables for you are the ones that exist for the sake of customization. Emacs does not (usually) change the values of these variables; instead, you set the values, and thereby alter and control the behavior of certain Emacs commands. These variables are called options. Most options are documented in this manual and appear in the Variable Index (see section Variable Index).

One example of a variable which is an option is fill-column, which specifies the position of the right margin (as a number of characters from the left margin) to be used by the fill commands (see section 20.6 Filling Text).

27.3.1 Examining and Setting Variables

C-h v

M-x describe-variable

Print the value and documentation of a variable.

M-x set-variable

Change the value of a variable.

To examine the value of a single variable, use C-h v (describe-variable), which reads a variable name using the minibuffer, with completion. It prints both the value and the documentation of the variable.

C-h v fill-column RET

prints something like:

fill-column's value is 75

Documentation:
*Column beyond which automatic line-wrapping should happen.
Automatically becomes local when set in any fashion.

The star at the beginning of the documentation indicates that this variable is an option. C-h v is not restricted to options; it allows any variable name.

If you know which option you want to set, you can use M-x set-variable to set it. This prompts for the variable name in the minibuffer (with completion), and then prompts for a Lisp expression for the new value using the minibuffer a second time. For example,

M-x set-variable RET fill-column RET 75 RET

sets fill-column to 75, as if you had executed the Lisp expression (setq fill-column 75).

Setting variables in this way, like all means of customizing Emacs except where explicitly stated, affects only the current Emacs session.

27.3.2 Easy Customization Interface

A convenient way to find the user option variables that you want to change, and then change them, is with C-h C (customize). This command creates a customization buffer with which you can browse through the Emacs user options in a logically organized structure, then edit and set their values. You can also use the customization buffer to save settings permanently. (Not all Emacs user options are included in this structure as of yet, but we are adding the rest.)

27.3.2.1 Customization Groups

For customization purposes, user options are organized into groups to help you find them. Groups are collected into bigger groups, all the way up to a master group called Emacs.

C-h C (customize) creates a customization buffer that shows the top-level Emacs group and the second-level groups immediately under it. It looks like this, in part:

/- Emacs group: ---------------------------------------------------\
      [State]: visible group members are all at standard settings.
   Customization of the One True Editor.
   See also [Manual].

 [Open] Editing group
Basic text editing facilities.

 [Open] External group
Interfacing to external utilities.

more second-level groups

\- Emacs group end ------------------------------------------------/

This says that the buffer displays the contents of the Emacs group. The other groups are listed because they are its contents. But they are listed differently, without indentation and dashes, because their contents are not included. Each group has a single-line documentation string; the Emacs group also has a `[State]' line.

Most of the text in the customization buffer is read-only, but it typically includes some editable fields that you can edit. There are also active fields; this means a field that does something when you invoke it. To invoke an active field, either click on it with Mouse-1, or move point to it and type RET.

For example, the phrase `[Open]' that appears in a second-level group is an active field. Invoking the `[Open]' field for a group opens up a new customization buffer, which shows that group and its contents. This field is a kind of hypertext link to another group.

The Emacs group does not include any user options itself, but other groups do. By examining various groups, you will eventually find the options and faces that belong to the feature you are interested in customizing. Then you can use the customization buffer to set them.

You can view the structure of customization groups on a larger scale with M-x customize-browse. This command creates a special kind of customization buffer which shows only the names of the groups (and options and faces), and their structure.

In this buffer, you can show the contents of a group by invoking `[+]'. When the group contents are visible, this button changes to `[-]'; invoking that hides the group contents.

Each group, option or face name in this buffer has an active field which says `[Group]', `[Option]' or `[Face]'. Invoking that active field creates an ordinary customization buffer showing just that group and its contents, just that option, or just that face. This is the way to set values in it.

27.3.2.2 Changing an Option

Here is an example of what a user option looks like in the customization buffer:

Kill Ring Max: [Hide] 30
   [State]: this option is unchanged from its standard setting.
Maximum length of kill ring before oldest elements are thrown away.

The text following `[Hide]', `30' in this case, indicates the current value of the option. If you see `[Show]' instead of `[Hide]', it means that the value is hidden; the customization buffer initially hides values that take up several lines. Invoke `[Show]' to show the value.

The line after the option name indicates the customization state of the option: in the example above, it says you have not changed the option yet. The word `[State]' at the beginning of this line is active; you can get a menu of various operations by invoking it with Mouse-1 or RET. These operations are essential for customizing the variable.

The line after the `[State]' line displays the beginning of the option's documentation string. If there are more lines of documentation, this line ends with `[More]'; invoke this to show the full documentation string.

To enter a new value for `Kill Ring Max', move point to the value and edit it textually. For example, you can type M-d, then insert another number.

When you begin to alter the text, you will see the `[State]' line change to say that you have edited the value:

[State]: you have edited the value as text, but not set the option.

Editing the value does not actually set the option variable. To do that, you must set the option. To do this, invoke the word `[State]' and choose `Set for Current Session'.

The state of the option changes visibly when you set it:

[State]: you have set this option, but not saved it for future sessions.

You don't have to worry about specifying a value that is not valid; setting the option checks for validity and will not really install an unacceptable value.

While editing a value or field that is a file name, directory name, command name, or anything else for which completion is defined, you can type M-TAB (widget-complete) to do completion.

Some options have a small fixed set of possible legitimate values. These options don't let you edit the value textually. Instead, an active field `[Value Menu]' appears before the value; invoke this field to edit the value. For a boolean "on or off" value, the active field says `[Toggle]', and it changes to the other value. `[Value Menu]' and `[Toggle]' edit the buffer; the changes take effect when you use the `Set for Current Session' operation.

Some options have values with complex structure. For example, the value of load-path is a list of directories. Here is how it appears in the customization buffer:

Load Path:
[INS] [DEL] [Current dir?]: /usr/local/share/emacs/19.34.94/site-lisp
[INS] [DEL] [Current dir?]: /usr/local/share/emacs/site-lisp
[INS] [DEL] [Current dir?]: /usr/local/share/emacs/19.34.94/leim
[INS] [DEL] [Current dir?]: /usr/local/share/emacs/19.34.94/lisp
[INS] [DEL] [Current dir?]: /build/emacs/e19/lisp
[INS] [DEL] [Current dir?]: /build/emacs/e19/lisp/gnus
[INS]
   [State]: this item has been changed outside the customization buffer.
List of directories to search for files to load....

Each directory in the list appears on a separate line, and each line has several editable or active fields.

You can edit any of the directory names. To delete a directory from the list, invoke `[DEL]' on that line. To insert a new directory in the list, invoke `[INS]' at the point where you want to insert it.

You can also invoke `[Current dir?]' to switch between including a specific named directory in the path, and including nil in the path. (nil in a search path means "try the current directory.")

Two special commands, TAB and S-TAB, are useful for moving through the customization buffer. TAB (widget-forward) moves forward to the next active or editable field; S-TAB (widget-backward) moves backward to the previous active or editable field.

Typing RET on an editable field also moves forward, just like TAB. The reason for this is that people have a tendency to type RET when they are finished editing a field. If you have occasion to insert a newline in an editable field, use C-o or C-q C-j,

Setting the option changes its value in the current Emacs session; saving the value changes it for future sessions as well. This works by writing code into your init file so as to set the option variable again each time you start Emacs. See section 27.7 The Init File. To save the option, invoke `[State]' and select the `Save for Future Sessions' operation.

You can also restore the option to its standard value by invoking `[State]' and selecting the `Reset' operation. There are actually three reset operations:

`Reset to Current'

If you have made some modifications and not yet set the option, this restores the text in the customization buffer to match the actual value.

`Reset to Saved'

This restores the value of the option to the last saved value, and updates the text accordingly.

`Reset to Standard Settings'

This sets the option to its standard value, and updates the text accordingly. This also eliminates any saved value for the option, so that you will get the standard value in future Emacs sessions.

The state of a group indicates whether anything in that group has been edited, set or saved. You can select `Set for Current Session', `Save for Future Sessions' and the various kinds of `Reset' operation for the group; these operations on the group apply to all options in the group and its subgroups.

Near the top of the customization buffer there are two lines containing several active fields:

 [Set] [Save] [Reset]  [Done]

Invoking `[Done]' buries this customization buffer. Each of the other fields performs an operation--set, save or reset--on each of the items in the buffer that could meaningfully be set, saved or reset.

27.3.2.3 Customizing Faces

In addition to user options, some customization groups also include faces. When you show the contents of a group, both the user options and the faces in the group appear in the customization buffer. Here is an example of how a face looks:

Custom Changed Face: (sample)
   [State]: this face is unchanged from its standard setting.
Face used when the customize item has been changed.
Parent groups: [Custom Magic Faces]
Attributes: [ ] Bold: [Toggle]  off (nil)
            [ ] Italic: [Toggle]  off (nil)
            [ ] Underline: [Toggle]  off (nil)
            [ ] Foreground: white       (sample)
            [ ] Background: blue        (sample)
            [ ] Inverse: [Toggle]  off (nil)
            [ ] Stipple:
            [ ] Font Family:
            [ ] Size:
            [ ] Strikethru: off

Each face attribute has its own line. The `[x]' field before the attribute name indicates whether the attribute is enabled; `X' means that it is. You can enable or disable the attribute by invoking that field. When the attribute is enabled, you can change the attribute value in the usual ways.

See section 27.9 Faces, for description of how face-frob-from-locale-first variable affects changing `Bold' and `Italic' attributes.

Setting, saving and resetting a face work like the same operations for options (see section 27.3.2.2 Changing an Option).

A face can specify different appearances for different types of display. For example, a face can make text red on a color display, but use a bold font on a monochrome display. To specify multiple appearances for a face, select `Show Display Types' in the menu you get from invoking `[State]'.

27.3.2.4 Customizing Specific Items

Instead of finding the options you want to change by moving down through the structure of groups, you can specify the particular option, face or group that you want to customize.

M-x customize-option RET option RET

Set up a customization buffer with just one option, option.

M-x customize-face RET face RET

Set up a customization buffer with just one face, face.

M-x customize-group RET group RET

Set up a customization buffer with just one group, group.

M-x customize-apropos RET regexp RET

Set up a customization buffer with all the options, faces and groups that match regexp.

M-x customize-saved

Set up a customization buffer containing all options and faces that you have saved with customization buffers.

M-x customize-customized

Set up a customization buffer containing all options and faces that you have customized but not saved.

If you want to alter a particular user option variable with the customization buffer, and you know its name, you can use the command M-x customize-option and specify the option name. This sets up the customization buffer with just one option--the one that you asked for. Editing, setting and saving the value work as described above, but only for the specified option.

Likewise, you can modify a specific face, chosen by name, using M-x customize-face.

You can also set up the customization buffer with a specific group, using M-x customize-group. The immediate contents of the chosen group, including option variables, faces, and other groups, all appear as well. However, these subgroups' own contents start out hidden. You can show their contents in the usual way, by invoking `[Show]'.

To control more precisely what to customize, you can use M-x customize-apropos. You specify a regular expression as argument; then all options, faces and groups whose names match this regular expression are set up in the customization buffer. If you specify an empty regular expression, this includes all groups, options and faces in the customization buffer (but that takes a long time).

If you change option values and then decide the change was a mistake, you can use two special commands to revisit your previous changes. Use customize-saved to look at the options and faces that you have saved. Use M-x customize-customized to look at the options and faces that you have set but not saved.

27.3.3 Editing Variable Values

M-x list-options

Display a buffer listing names, values, and documentation of all options.

M-x edit-options

Change option values by editing a list of options.

M-x list-options displays a list of all Emacs option variables in an Emacs buffer named `*List Options*'. Each option is shown with its documentation and its current value. Here is what a portion of it might look like:

;; exec-path:
("." "/usr/local/bin" "/usr/ucb" "/bin" "/usr/bin" "/u2/emacs/etc")
*List of directories to search programs to run in subprocesses.
Each element is a string (directory name)
or nil (try the default directory).
;;
;; fill-column:
75
*Column beyond which automatic line-wrapping should happen.
Automatically becomes local when set in any fashion.
;;

M-x edit-options goes one step further and immediately selects the `*List Options*' buffer; this buffer uses the major mode Options mode, which provides commands that allow you to point at an option and change its value:

s

Set the variable point is in or near to a new value read using the minibuffer.

x

Toggle the variable point is in or near: if the value was nil, it becomes t; otherwise it becomes nil.

1

Set the variable point is in or near to t.

0

Set the variable point is in or near to nil.

n

p

Move to the next or previous variable.

27.3.4 Local Variables

M-x make-local-variable

Make a variable have a local value in the current buffer.

M-x kill-local-variable

Make a variable use its global value in the current buffer.

M-x make-variable-buffer-local

Mark a variable so that setting it will make it local to the buffer that is current at that time.

You can make any variable local to a specific Emacs buffer. This means that the variable's value in that buffer is independent of its value in other buffers. A few variables are always local in every buffer. All other Emacs variables have a global value which is in effect in all buffers that have not made the variable local.

Major modes always make the variables they set local to the buffer. This is why changing major modes in one buffer has no effect on other buffers.

M-x make-local-variable reads the name of a variable and makes it local to the current buffer. Further changes in this buffer will not affect others, and changes in the global value will not affect this buffer.

M-x make-variable-buffer-local reads the name of a variable and changes the future behavior of the variable so that it automatically becomes local when it is set. More precisely, once you have marked a variable in this way, the usual ways of setting the variable will automatically invoke make-local-variable first. We call such variables per-buffer variables.

Some important variables have been marked per-buffer already. They include abbrev-mode, auto-fill-function, case-fold-search, comment-column, ctl-arrow, fill-column, fill-prefix, indent-tabs-mode, left-margin,
mode-line-format, overwrite-mode, selective-display-ellipses,
selective-display, tab-width, and truncate-lines. Some other variables are always local in every buffer, but they are used for internal purposes.

Note: the variable auto-fill-function was formerly named auto-fill-hook.

If you want a variable to cease to be local to the current buffer, call M-x kill-local-variable and provide the name of a variable to the prompt. The global value of the variable is again in effect in this buffer. Setting the major mode kills all the local variables of the buffer.

To set the global value of a variable, regardless of whether the variable has a local value in the current buffer, you can use the Lisp function setq-default. It works like setq. If there is a local value in the current buffer, the local value is not affected by setq-default; thus, the new global value may not be visible until you switch to another buffer, as in the case of:

(setq-default fill-column 75)

setq-default is the only way to set the global value of a variable that has been marked with make-variable-buffer-local.

Programs can look at a variable's default value with default-value. This function takes a symbol as an argument and returns its default value. The argument is evaluated; usually you must quote it explicitly, as in the case of:

(default-value 'fill-column)

27.3.5 Local Variables in Files

A file can contain a local variables list, which specifies the buffer-local values to use for certain Emacs variables when that file is edited. Visiting the file checks for a local variables list and makes each variable in the list local to the buffer in which the file is visited, with the value specified in the file.

A local variables list goes near the end of the file, in the last page. (It is often best to put it on a page by itself.) The local variables list starts with a line containing the string `Local Variables:', and ends with a line containing the string `End:'. In between come the variable names and values, one set per line, as `variable: value'. The values are not evaluated; they are used literally.

The line which starts the local variables list does not have to say just `Local Variables:'. If there is other text before `Local Variables:', that text is called the prefix, and if there is other text after, that is called the suffix. If a prefix or suffix are present, each entry in the local variables list should have the prefix before it and the suffix after it. This includes the `End:' line. The prefix and suffix are included to disguise the local variables list as a comment so the compiler or text formatter will ignore it. If you do not need to disguise the local variables list as a comment in this way, there is no need to include a prefix or a suffix.

Two "variable" names are special in a local variables list: a value for the variable mode sets the major mode, and a value for the variable eval is simply evaluated as an expression and the value is ignored. These are not real variables; setting them in any other context does not have the same effect. If mode is used in a local variables list, it should be the first entry in the list.

Here is an example of a local variables list:

;;; Local Variables: ***
;;; mode:lisp ***
;;; comment-column:0 ***
;;; comment-start: ";;; "  ***
;;; comment-end:"***" ***
;;; End: ***

Note that the prefix is `;;; ' and the suffix is ` ***'. Note also that comments in the file begin with and end with the same strings. Presumably the file contains code in a language which is enough like Lisp for Lisp mode to be useful but in which comments start and end differently. The prefix and suffix are used in the local variables list to make the list look like several lines of comments when the compiler or interpreter for that language reads the file.

The start of the local variables list must be no more than 3000 characters from the end of the file, and must be in the last page if the file is divided into pages. Otherwise, Emacs will not notice it is there. The purpose is twofold: a stray `Local Variables:' not in the last page does not confuse Emacs, and Emacs never needs to search a long file that contains no page markers and has no local variables list.

You may be tempted to turn on minor modes like Auto Fill mode with a local variable list. That is inappropriate. Those behaviors that seem appropriate for almost any personal taste, such as setting up the syntax table "symbol constituent" character class, are collected into a major mode. But whether you use Auto Fill mode or not is a matter of personal taste, not a matter of the contents of particular files. If you want to use Auto Fill, set up major mode hooks with your init file to turn it on (when appropriate) for you alone (see section 27.7 The Init File). Don't use a local variable list that would impose your taste on everyone working with the file.

XEmacs allows you to specify local variables in the first line of a file, in addition to specifying them in the Local Variables section at the end of a file.

If the first line of a file contains two occurrences of `-*-', XEmacs uses the information between them to determine what the major mode and variable settings should be. For example, these are all legal:

        ;;; -*- mode: emacs-lisp -*-
        ;;; -*- mode: postscript; version-control: never -*-
        ;;; -*- tags-file-name: "/foo/bar/TAGS" -*-

For historical reasons, the syntax `-*- modename -*-' is allowed as well; for example, you can use:

        ;;; -*- emacs-lisp -*-

The variable enable-local-variables controls the use of local variables lists in files you visit. The value can be t, nil, or something else. A value of t means local variables lists are obeyed; nil means they are ignored; anything else means query.

The command M-x normal-mode always obeys local variables lists and ignores this variable.

27.4 Keyboard Macros

A keyboard macro is a command defined by the user to abbreviate a sequence of keys. For example, if you discover that you are about to type C-n C-d forty times, you can speed your work by defining a keyboard macro to invoke C-n C-d and calling it with a repeat count of forty.

C-x (

Start defining a keyboard macro (start-kbd-macro).

C-x )

End the definition of a keyboard macro (end-kbd-macro).

C-x e

Execute the most recent keyboard macro (call-last-kbd-macro).

C-u C-x (

Re-execute last keyboard macro, then add more keys to its definition.

C-x q

When this point is reached during macro execution, ask for confirmation (kbd-macro-query).

M-x name-last-kbd-macro

Give a command name (for the duration of the session) to the most recently defined keyboard macro.

M-x insert-kbd-macro

Insert in the buffer a keyboard macro's definition, as Lisp code.

Keyboard macros differ from other Emacs commands in that they are written in the Emacs command language rather than in Lisp. This makes it easier for the novice to write them and makes them more convenient as temporary hacks. However, the Emacs command language is not powerful enough as a programming language to be useful for writing anything general or complex. For such things, Lisp must be used.

You define a keyboard macro by executing the commands which are its definition. Put differently, as you are defining a keyboard macro, the definition is being executed for the first time. This way, you see what the effects of your commands are, and don't have to figure them out in your head. When you are finished, the keyboard macro is defined and also has been executed once. You can then execute the same set of commands again by invoking the macro.

27.4.1 Basic Use

To start defining a keyboard macro, type C-x ( (start-kbd-macro). From then on, anything you type continues to be executed, but also becomes part of the definition of the macro. `Def' appears in the mode line to remind you of what is going on. When you are finished, the C-x ) command (end-kbd-macro) terminates the definition, without becoming part of it.

For example,

C-x ( M-f foo C-x )

defines a macro to move forward a word and then insert `foo'.

You can give C-x ) a repeat count as an argument, in which case it repeats the macro that many times right after defining it, but defining the macro counts as the first repetition (since it is executed as you define it). If you give C-x ) an argument of 4, it executes the macro immediately 3 additional times. An argument of zero to C-x e or C-x ) means repeat the macro indefinitely (until it gets an error or you type C-g).

Once you have defined a macro, you can invoke it again with the C-x e command (call-last-kbd-macro). You can give the command a repeat count numeric argument to execute the macro many times.

To repeat an operation at regularly spaced places in the text, define a macro and include as part of the macro the commands to move to the next place you want to use it. For example, if you want to change each line, you should position point at the start of a line, and define a macro to change that line and leave point at the start of the next line. Repeating the macro will then operate on successive lines.

After you have terminated the definition of a keyboard macro, you can add to the end of its definition by typing C-u C-x (. This is equivalent to plain C-x ( followed by retyping the whole definition so far. As a consequence it re-executes the macro as previously defined.

27.4.2 Naming and Saving Keyboard Macros

To save a keyboard macro for longer than until you define the next one, you must give it a name using M-x name-last-kbd-macro. This reads a name as an argument using the minibuffer and defines that name to execute the macro. The macro name is a Lisp symbol, and defining it in this way makes it a valid command name for calling with M-x or for binding a key to with global-set-key (see section 27.5.1 Keymaps). If you specify a name that has a prior definition other than another keyboard macro, Emacs prints an error message and nothing is changed.

Once a macro has a command name, you can save its definition in a file. You can then use it in another editing session. First visit the file you want to save the definition in. Then use the command:

M-x insert-kbd-macro RET macroname RET

This inserts some Lisp code that, when executed later, will define the same macro with the same definition it has now. You need not understand Lisp code to do this, because insert-kbd-macro writes the Lisp code for you. Then save the file. You can load the file with load-file (see section 22.3 Libraries of Lisp Code for Emacs). If the file you save in is your initialization file (see section 27.7 The Init File), then the macro will be defined each time you run Emacs.

If you give insert-kbd-macro a prefix argument, it creates additional Lisp code to record the keys (if any) that you have bound to the keyboard macro, so that the macro is reassigned the same keys when you load the file.

27.4.3 Executing Macros With Variations

You can use C-x q (kbd-macro-query), to get an effect similar to that of query-replace. The macro asks you each time whether to make a change. When you are defining the macro, type C-x q at the point where you want the query to occur. During macro definition, the C-x q does nothing, but when you invoke the macro, C-x q reads a character from the terminal to decide whether to continue.

The special answers to a C-x q query are SPC, DEL, C-d, C-l, and C-r. Any other character terminates execution of the keyboard macro and is then read as a command. SPC means to continue. DEL means to skip the remainder of this repetition of the macro, starting again from the beginning in the next repetition. C-d means to skip the remainder of this repetition and cancel further repetition. C-l redraws the frame and asks you again for a character to specify what to do. C-r enters a recursive editing level, in which you can perform editing that is not part of the macro. When you exit the recursive edit using C-M-c, you are asked again how to continue with the keyboard macro. If you type a SPC at this time, the rest of the macro definition is executed. It is up to you to leave point and the text in a state such that the rest of the macro will do what you want.

C-u C-x q, which is C-x q with a numeric argument, performs a different function. It enters a recursive edit reading input from the keyboard, both when you type it during the definition of the macro and when it is executed from the macro. During definition, the editing you do inside the recursive edit does not become part of the macro. During macro execution, the recursive edit gives you a chance to do some particularized editing. See section 26.10 Recursive Editing Levels.

27.5 Customizing Key Bindings

This section deals with the keymaps that define the bindings between keys and functions, and shows how you can customize these bindings.

A command is a Lisp function whose definition provides for interactive use. Like every Lisp function, a command has a function name, which is a Lisp symbol whose name usually consists of lower case letters and hyphens.

27.5.1 Keymaps

The bindings between characters and command functions are recorded in data structures called keymaps. Emacs has many of these. One, the global keymap, defines the meanings of the single-character keys that are defined regardless of major mode. It is the value of the variable global-map.

Each major mode has another keymap, its local keymap, which contains overriding definitions for the single-character keys that are redefined in that mode. Each buffer records which local keymap is installed for it at any time, and the current buffer's local keymap is the only one that directly affects command execution. The local keymaps for Lisp mode, C mode, and many other major modes always exist even when not in use. They are the values of the variables lisp-mode-map, c-mode-map, and so on. For less frequently used major modes, the local keymap is sometimes constructed only when the mode is used for the first time in a session, to save space.

There are local keymaps for the minibuffer, too; they contain various completion and exit commands.

• minibuffer-local-map is used for ordinary input (no completion).
• minibuffer-local-ns-map is similar, except that SPC exits just like RET. This is used mainly for Mocklisp compatibility.
• minibuffer-local-completion-map is for permissive completion.
• minibuffer-local-must-match-map is for strict completion and for cautious completion.
• repeat-complex-command-map is for use in C-x ESC.
• isearch-mode-map contains the bindings of the special keys which are bound in the pseudo-mode entered with C-s and C-r.

Finally, each prefix key has a keymap which defines the key sequences that start with it. For example, ctl-x-map is the keymap used for characters following a C-x.

• ctl-x-map is the variable name for the map used for characters that follow C-x.
• help-map is used for characters that follow C-h.
• esc-map is for characters that follow ESC. All Meta characters are actually defined by this map.
• ctl-x-4-map is for characters that follow C-x 4.
• mode-specific-map is for characters that follow C-c.

The definition of a prefix key is the keymap to use for looking up the following character. Sometimes the definition is actually a Lisp symbol whose function definition is the following character keymap. The effect is the same, but it provides a command name for the prefix key that you can use as a description of what the prefix key is for. Thus the binding of C-x is the symbol Ctl-X-Prefix, whose function definition is the keymap for C-x commands, the value of ctl-x-map.

Prefix key definitions can appear in either the global map or a local map. The definitions of C-c, C-x, C-h, and ESC as prefix keys appear in the global map, so these prefix keys are always available. Major modes can locally redefine a key as a prefix by putting a prefix key definition for it in the local map.

A mode can also put a prefix definition of a global prefix character such as C-x into its local map. This is how major modes override the definitions of certain keys that start with C-x. This case is special, because the local definition does not entirely replace the global one. When both the global and local definitions of a key are other keymaps, the next character is looked up in both keymaps, with the local definition overriding the global one. The character after the C-x is looked up in both the major mode's own keymap for redefined C-x commands and in ctl-x-map. If the major mode's own keymap for C-x commands contains nil, the definition from the global keymap for C-x commands is used.

27.5.2 Changing Key Bindings

You can redefine an Emacs key by changing its entry in a keymap. You can change the global keymap, in which case the change is effective in all major modes except those that have their own overriding local definitions for the same key. Or you can change the current buffer's local map, which affects all buffers using the same major mode.

27.5.2.1 Changing Key Bindings Interactively

M-x global-set-key RET key cmd RET

Defines key globally to run cmd.

M-x local-set-key RET keys cmd RET

Defines key locally (in the major mode now in effect) to run cmd.

M-x local-unset-key RET keys RET

Removes the local binding of key.

cmd is a symbol naming an interactively-callable function.

When called interactively, key is the next complete key sequence that you type. When called as a function, key is a string, a vector of events, or a vector of key-description lists as described in the define-key function description. The binding goes in the current buffer's local map, which is shared with other buffers in the same major mode.

The following example:

M-x global-set-key RET C-f next-line RET

redefines C-f to move down a line. The fact that cmd is read second makes it serve as a kind of confirmation for key.

These functions offer no way to specify a particular prefix keymap as the one to redefine in, but that is not necessary, as you can include prefixes in key. key is read by reading characters one by one until they amount to a complete key (that is, not a prefix key). Thus, if you type C-f for key, Emacs enters the minibuffer immediately to read cmd. But if you type C-x, another character is read; if that character is 4, another character is read, and so on. For example,

M-x global-set-key RET C-x 4 $ spell-other-window RET

redefines C-x 4 $ to run the (fictitious) command spell-other-window.

The most general way to modify a keymap is the function define-key, used in Lisp code (such as your init file). define-key takes three arguments: the keymap, the key to modify in it, and the new definition. See section 27.7 The Init File, for an example. substitute-key-definition is used similarly; it takes three arguments, an old definition, a new definition, and a keymap, and redefines in that keymap all keys that were previously defined with the old definition to have the new definition instead.

27.5.2.2 Changing Key Bindings Programmatically

You can use the functions global-set-key and define-key to rebind keys under program control.

(global-set-key keys cmd)

Defines keys globally to run cmd.

(define-key keymap keys def)

Defines keys to run def in the keymap keymap.

keymap is a keymap object.

keys is the sequence of keystrokes to bind.

def is anything that can be a key's definition:

• nil, meaning key is undefined in this keymap
• A command, that is, a Lisp function suitable for interactive calling
• A string or key sequence vector, which is treated as a keyboard macro
• A keymap to define a prefix key
• A symbol so that when the key is looked up, the symbol stands for its function definition, which should at that time be one of the above, or another symbol whose function definition is used, and so on
• A cons, (string . defn), meaning that defn is the definition (defn should be a valid definition in its own right)
• A cons, (keymap . char), meaning use the definition of char in map keymap

For backward compatibility, XEmacs allows you to specify key sequences as strings. However, the preferred method is to use the representations of key sequences as vectors of keystrokes. See section 2. Keystrokes, Key Sequences, and Key Bindings, for more information about the rules for constructing key sequences.

Emacs allows you to abbreviate representations for key sequences in most places where there is no ambiguity. Here are some rules for abbreviation:

• The keysym by itself is equivalent to a list of just that keysym, i.e., f1 is equivalent to (f1).
• A keystroke by itself is equivalent to a vector containing just that keystroke, i.e., (control a) is equivalent to [(control a)].
• You can use ASCII codes for keysyms that have them. i.e., 65 is equivalent to A. (This is not so much an abbreviation as an alternate representation.)

Here are some examples of programmatically binding keys:

;;;  Bind my-command to f1
(global-set-key 'f1 'my-command)

;;;  Bind my-command to Shift-f1
(global-set-key '(shift f1) 'my-command)

;;; Bind my-command to C-c Shift-f1
(global-set-key '[(control c) (shift f1)] 'my-command)

;;; Bind my-command to the middle mouse button.
(global-set-key 'button2 'my-command)

;;; Bind my-command to META CTL Right Mouse Button
;;; in the keymap that is in force when you are running dired.
(define-key dired-mode-map '(meta control button3) 'my-command)

27.5.2.3 Using Strings for Changing Key Bindings

For backward compatibility, you can still use strings to represent key sequences. Thus you can use commands like the following:

;;; Bind end-of-line to C-f
(global-set-key "\C-f" 'end-of-line)

Note, however, that in some cases you may be binding more than one key sequence by using a single command. This situation can arise because in ASCII, C-i and TAB have the same representation. Therefore, when Emacs sees:

(global-set-key "\C-i" 'end-of-line)

it is unclear whether the user intended to bind C-i or TAB. The solution XEmacs adopts is to bind both of these key sequences.

After binding a command to two key sequences with a form like:

        (define-key global-map "\^X\^I" 'command-1)

it is possible to redefine only one of those sequences like so:

        (define-key global-map [(control x) (control i)] 'command-2)
        (define-key global-map [(control x) tab] 'command-3)

This applies only when running under a window system. If you are talking to Emacs through an ASCII-only channel, you do not get any of these features.

Here is a table of pairs of key sequences that behave in a similar fashion:

        control h      backspace
        control l      clear
        control i      tab
        control m      return
        control j      linefeed
        control [      escape
        control @      control space

27.5.3 Disabling Commands

Disabling a command marks it as requiring confirmation before it can be executed. The purpose of disabling a command is to prevent beginning users from executing it by accident and being confused.

The direct mechanism for disabling a command is to have a non-nil disabled property on the Lisp symbol for the command. These properties are normally set by the user's init file with Lisp expressions such as:

(put 'delete-region 'disabled t)

See section 27.7 The Init File.

If the value of the disabled property is a string, that string is included in the message printed when the command is used:

(put 'delete-region 'disabled
     "Text deleted this way cannot be yanked back!\n")

You can disable a command either by editing the init file directly or with the command M-x disable-command, which edits the init file for you. See section 27.7 The Init File.

When you attempt to invoke a disabled command interactively in Emacs, a window is displayed containing the command's name, its documentation, and some instructions on what to do next; then Emacs asks for input saying whether to execute the command as requested, enable it and execute, or cancel it. If you decide to enable the command, you are asked whether to do this permanently or just for the current session. Enabling permanently works by automatically editing your init file. You can use M-x enable-command at any time to enable any command permanently.

Whether a command is disabled is independent of what key is used to invoke it; it also applies if the command is invoked using M-x. Disabling a command has no effect on calling it as a function from Lisp programs.

27.6 The Syntax Table

All the Emacs commands which parse words or balance parentheses are controlled by the syntax table. The syntax table specifies which characters are opening delimiters, which are parts of words, which are string quotes, and so on. Actually, each major mode has its own syntax table (though sometimes related major modes use the same one) which it installs in each buffer that uses that major mode. The syntax table installed in the current buffer is the one that all commands use, so we call it "the" syntax table. A syntax table is a Lisp object, a vector of length 256 whose elements are numbers.

27.6.1 Information About Each Character

The syntax table entry for a character is a number that encodes six pieces of information:

• The syntactic class of the character, represented as a small integer
• The matching delimiter, for delimiter characters only (the matching delimiter of `(' is `)', and vice versa)
• A flag saying whether the character is the first character of a two-character comment starting sequence
• A flag saying whether the character is the second character of a two-character comment starting sequence
• A flag saying whether the character is the first character of a two-character comment ending sequence
• A flag saying whether the character is the second character of a two-character comment ending sequence

The syntactic classes are stored internally as small integers, but are usually described to or by the user with characters. For example, `(' is used to specify the syntactic class of opening delimiters. Here is a table of syntactic classes, with the characters that specify them.

`-'

The class of whitespace characters. Avoid use of the formerly advertised , because it is not supported by GNU Emacs.

`w'

The class of word-constituent characters.

`_'

The class of characters that are part of symbol names but not words. This class is represented by `_' because the character `_' has this class in both C and Lisp.

`.'

The class of punctuation characters that do not fit into any other special class.

`('

The class of opening delimiters.

`)'

The class of closing delimiters.

`''

The class of expression-adhering characters. These characters are part of a symbol if found within or adjacent to one, and are part of a following expression if immediately preceding one, but are like whitespace if surrounded by whitespace.

`"'

The class of string-quote characters. They match each other in pairs, and the characters within the pair all lose their syntactic significance except for the `\' and `/' classes of escape characters, which can be used to include a string-quote inside the string.

`$'

The class of self-matching delimiters. This is intended for TeX's `$', which is used both to enter and leave math mode. Thus, a pair of matching `$' characters surround each piece of math mode TeX input. A pair of adjacent `$' characters act like a single one for purposes of matching.

`/'

The class of escape characters that always just deny the following character its special syntactic significance. The character after one of these escapes is always treated as alphabetic.

`\'

The class of C-style escape characters. In practice, these are treated just like `/'-class characters, because the extra possibilities for C escapes (such as being followed by digits) have no effect on where the containing expression ends.

`<'

The class of comment-starting characters. Only single-character comment starters (such as `;' in Lisp mode) are represented this way.

`>'

The class of comment-ending characters. Newline has this syntax in Lisp mode.

The characters flagged as part of two-character comment delimiters can have other syntactic functions most of the time. For example, `/' and `*' in C code, when found separately, have nothing to do with comments. The comment-delimiter significance overrides when the pair of characters occur together in the proper order. Only the list and sexp commands use the syntax table to find comments; the commands specifically for comments have other variables that tell them where to find comments. Moreover, the list and sexp commands notice comments only if parse-sexp-ignore-comments is non-nil. This variable is set to nil in modes where comment-terminator sequences are liable to appear where there is no comment, for example, in Lisp mode where the comment terminator is a newline but not every newline ends a comment.

27.6.2 Altering Syntax Information

It is possible to alter a character's syntax table entry by storing a new number in the appropriate element of the syntax table, but it would be hard to determine what number to use. Emacs therefore provides a command that allows you to specify the syntactic properties of a character in a convenient way.

M-x modify-syntax-entry is the command to change a character's syntax. It can be used interactively and is also used by major modes to initialize their own syntax tables. Its first argument is the character to change. The second argument is a string that specifies the new syntax. When called from Lisp code, there is a third, optional argument, which specifies the syntax table in which to make the change. If not supplied, or if this command is called interactively, the third argument defaults to the current buffer's syntax table.

1. The first character in the string specifies the syntactic class. It is one of the characters in the previous table (see section 27.6.1 Information About Each Character).

2. The second character is the matching delimiter. For a character that is not an opening or closing delimiter, this should be a space, and may be omitted if no following characters are needed.

3. The remaining characters are flags. The flag characters allowed are:

   `1'

   Flag this character as the first of a two-character comment starting sequence.

   `2'

   Flag this character as the second of a two-character comment starting sequence.

   `3'

   Flag this character as the first of a two-character comment ending sequence.

   `4'

   Flag this character as the second of a two-character comment ending sequence.

Use C-h s (describe-syntax) to display a description of the contents of the current syntax table. The description of each character includes both the string you have to pass to modify-syntax-entry to set up that character's current syntax, and some English to explain that string if necessary.

27.7 The Init File

When you start Emacs, it normally loads either `.xemacs/init.el' or the file `.emacs' (whichever comes first) in your home directory. This file, if it exists, should contain Lisp code. It is called your initialization file or init file. Use the command line switch `-q' to tell Emacs whether to load an init file (see section 3. Entering and Exiting Emacs). Use the command line switch `-user-init-file' (see section 3.2 Command Line Switches and Arguments) to tell Emacs to load a different file instead of `~/.xemacs/init.el'/`~/.emacs'.

When the init file is read, the variable user-init-file says which init file was loaded.

At some sites there is a default init file, which is the library named `default.el', found via the standard search path for libraries. The Emacs distribution contains no such library; your site may create one for local customizations. If this library exists, it is loaded whenever you start Emacs. But your init file, if any, is loaded first; if it sets inhibit-default-init non-nil, then `default' is not loaded.

If you have a large amount of code in your init file, you should byte-compile it to `~/.xemacs/init.elc' or `~/.emacs.elc'.

27.7.1 Init File Syntax

The init file contains one or more Lisp function call expressions. Each consists of a function name followed by arguments, all surrounded by parentheses. For example, (setq fill-column 60) represents a call to the function setq which is used to set the variable fill-column (see section 20.6 Filling Text) to 60.

The second argument to setq is an expression for the new value of the variable. This can be a constant, a variable, or a function call expression. In the init file, constants are used most of the time. They can be:

Numbers

Integers are written in decimal, with an optional initial minus sign.

If a sequence of digits is followed by a period and another sequence of digits, it is interpreted as a floating point number.

The number prefixes `#b', `#o', and `#x' are supported to represent numbers in binary, octal, and hexadecimal notation (or radix).

Strings

Lisp string syntax is the same as C string syntax with a few extra features. Use a double-quote character to begin and end a string constant.

Newlines and special characters may be present literally in strings. They can also be represented as backslash sequences: `\n' for newline, `\b' for backspace, `\r' for return, `\t' for tab, `\f' for formfeed (control-l), `\e' for escape, `\\' for a backslash, `\"' for a double-quote, or `\ooo' for the character whose octal code is ooo. Backslash and double-quote are the only characters for which backslash sequences are mandatory.

You can use `\C-' as a prefix for a control character, as in `\C-s' for ASCII Control-S, and `\M-' as a prefix for a Meta character, as in `\M-a' for Meta-A or `\M-\C-a' for Control-Meta-A.

Characters

Lisp character constant syntax consists of a `?' followed by either a character or an escape sequence starting with `\'. Examples: ?x, ?\n, ?\", ?\). Note that strings and characters are not interchangeable in Lisp; some contexts require one and some contexts require the other.

True

t stands for `true'.

False

nil stands for `false'.

Other Lisp objects

Write a single-quote (') followed by the Lisp object you want.

27.7.2 Init File Examples

Here are some examples of doing certain commonly desired things with Lisp expressions:

• Make TAB in C mode just insert a tab if point is in the middle of a line.

  (setq c-tab-always-indent nil)

  Here we have a variable whose value is normally t for `true' and the alternative is nil for `false'.

• Make searches case sensitive by default (in all buffers that do not override this).

  (setq-default case-fold-search nil)

  This sets the default value, which is effective in all buffers that do not have local values for the variable. Setting case-fold-search with setq affects only the current buffer's local value, which is probably not what you want to do in an init file.

• Make Text mode the default mode for new buffers.

  (setq default-major-mode 'text-mode)

  Note that text-mode is used because it is the command for entering the mode we want. A single-quote is written before it to make a symbol constant; otherwise, text-mode would be treated as a variable name.

• Turn on Auto Fill mode automatically in Text mode and related modes.

  (setq text-mode-hook '(lambda () (auto-fill-mode 1)))

  Here we have a variable whose value should be a Lisp function. The function we supply is a list starting with lambda, and a single quote is written in front of it to make it (for the purpose of this setq) a list constant rather than an expression. Lisp functions are not explained here; for mode hooks it is enough to know that (auto-fill-mode 1) is an expression that will be executed when Text mode is entered. You could replace it with any other expression that you like, or with several expressions in a row.

  (setq text-mode-hook 'turn-on-auto-fill)

  This is another way to accomplish the same result. turn-on-auto-fill is a symbol whose function definition is (lambda () (auto-fill-mode 1)).

• Load the installed Lisp library named `foo' (actually a file `foo.elc' or `foo.el' in a standard Emacs directory).

  (load "foo")

  When the argument to load is a relative pathname, not starting with `/' or `~', load searches the directories in load-path (see section 22.3.1 Loading Libraries).

• Load the compiled Lisp file `foo.elc' from your home directory.

  (load "~/foo.elc")

  Here an absolute file name is used, so no searching is done.

• Rebind the key C-x l to run the function make-symbolic-link.

  (global-set-key "\C-xl" 'make-symbolic-link)

  or

  (define-key global-map "\C-xl" 'make-symbolic-link)

  Note once again the single-quote used to refer to the symbol make-symbolic-link instead of its value as a variable.

• Do the same thing for C mode only.

  (define-key c-mode-map "\C-xl" 'make-symbolic-link)

• Bind the function key F1 to a command in C mode. Note that the names of function keys must be lower case.

  (define-key c-mode-map 'f1 'make-symbolic-link)

• Bind the shifted version of F1 to a command.

  (define-key c-mode-map '(shift f1) 'make-symbolic-link)

• Redefine all keys which now run next-line in Fundamental mode to run forward-line instead.

  (substitute-key-definition 'next-line 'forward-line global-map)

• Make C-x C-v undefined.

  (global-unset-key "\C-x\C-v")

  One reason to undefine a key is so that you can make it a prefix. Simply defining C-x C-v anything would make C-x C-v a prefix, but C-x C-v must be freed of any non-prefix definition first.

• Make `$' have the syntax of punctuation in Text mode. Note the use of a character constant for `$'.

  (modify-syntax-entry ?\$ "." text-mode-syntax-table)

• Enable the use of the command eval-expression without confirmation.

  (put 'eval-expression 'disabled nil)

27.7.3 Terminal-Specific Initialization

Each terminal type can have a Lisp library to be loaded into Emacs when it is run on that type of terminal. For a terminal type named termtype, the library is called `term/termtype' and it is found by searching the directories load-path as usual and trying the suffixes `.elc' and `.el'. Normally it appears in the subdirectory `term' of the directory where most Emacs libraries are kept.

The usual purpose of the terminal-specific library is to define the escape sequences used by the terminal's function keys using the library `keypad.el'. See the file `term/vt100.el' for an example of how this is done.

When the terminal type contains a hyphen, only the part of the name before the first hyphen is significant in choosing the library name. Thus, terminal types `aaa-48' and `aaa-30-rv' both use the library `term/aaa'. The code in the library can use (getenv "TERM") to find the full terminal type name.

The library's name is constructed by concatenating the value of the variable term-file-prefix and the terminal type. Your init file can prevent the loading of the terminal-specific library by setting term-file-prefix to nil. See section 27.7 The Init File.

The value of the variable term-setup-hook, if not nil, is called as a function of no arguments at the end of Emacs initialization, after both your init file and any terminal-specific library have been read. See section 27.7 The Init File. You can set the value in the init file to override part of any of the terminal-specific libraries and to define initializations for terminals that do not have a library.

27.8 Changing the Bell Sound

You can now change how the audible bell sounds using the variable sound-alist.

sound-alist's value is an list associating symbols with, among other things, strings of audio-data. When ding is called with one of the symbols, the associated sound data is played instead of the standard beep. This only works if you are logged in on the console of a machine with audio hardware. To listen to a sound of the provided type, call the function play-sound with the argument sound. You can also set the volume of the sound with the optional argument volume.

Each element of sound-alist is a list describing a sound. The first element of the list is the name of the sound being defined. Subsequent elements of the list are alternating keyword/value pairs:

sound

A string of raw sound data, or the name of another sound to play. The symbol t here means use the default X beep.

volume

An integer from 0-100, defaulting to bell-volume.

pitch

If using the default X beep, the pitch (Hz) to generate.

duration

If using the default X beep, the duration (milliseconds).

For compatibility, elements of `sound-alist' may also be of the form:

( sound-name . <sound> )
( sound-name <volume> <sound> )

You should probably add things to this list by calling the function load-sound-file.

Note that you can only play audio data if running on the console screen of a machine with audio hardware which emacs understands, which at this time means a Sun SparcStation, SGI, or HP9000s700.

Also note that the pitch, duration, and volume options are available everywhere, but most X servers ignore the `pitch' option.

The variable bell-volume should be an integer from 0 to 100, with 100 being loudest, which controls how loud the sounds emacs makes should be. Elements of the sound-alist may override this value. This variable applies to the standard X bell sound as well as sound files.

If the symbol t is in place of a sound-string, Emacs uses the default X beep. This allows you to define beep-types of different volumes even when not running on the console.

You can add things to this list by calling the function load-sound-file, which reads in an audio-file and adds its data to the sound-alist. You can specify the sound with the sound-name argument and the file into which the sounds are loaded with the filename argument. The optional volume argument sets the volume.

load-sound-file (filename sound-name &optional volume)

To load and install some sound files as beep-types, use the function load-default-sounds (note that this only works if you are on display 0 of a machine with audio hardware).

The following beep-types are used by Emacs itself. Other Lisp packages may use other beep types, but these are the ones that the C kernel of Emacs uses.

auto-save-error

An auto-save does not succeed

command-error

The Emacs command loop catches an error

undefined-key

You type a key that is undefined

undefined-click

You use an undefined mouse-click combination

no-completion

Completion was not possible

y-or-n-p

You type something other than the required y or n

yes-or-no-p

You type something other than yes or no

27.9 Faces

XEmacs has objects called extents and faces. An extent is a region of text and a face is a collection of textual attributes, such as fonts and colors. Every extent is displayed in some face; therefore, changing the properties of a face immediately updates the display of all associated extents. Faces can be frame-local: you can have a region of text that displays with completely different attributes when its buffer is viewed from a different X window.

The display attributes of faces may be specified either in Lisp or through the X resource manager.

Basic Xft support has been merged into the mainline, and it looks pretty good. However, customization UI and documentation still leaves a lot to be desired. Here's a first cut, as a separate node.