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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  Each minor mode is one feature you can turn on independently of any others.
27.2 Behaviors  Like minor modes, behaviors are independent of other features, but behaviors are usually enabled globally, while minor modes are per-buffer and often temporary.
27.3 Variables  Many Emacs commands examine Emacs variables to decide what to do; by setting variables, you can control their functioning.
27.4 Keyboard Macros  A keyboard macro records a sequence of keystrokes to be replayed with a single command.
27.5 Customizing Key Bindings  The keymaps say what command each key runs. By changing them, you can "redefine keys".
27.6 The Syntax Table  The syntax table controls how words and expressions are parsed.
27.7 The Init File  How to write common customizations in the init file.
27.8 Changing the Bell Sound  Changing how Emacs sounds the bell.
27.9 Faces  Changing the fonts and colors of a region of text.
27.11 Frame Components  Controlling the presence and positions of the menubar, toolbars, and gutters.
27.12 X Resources  X resources controlling various aspects of the behavior of XEmacs.


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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.


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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.


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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  Examining or setting one variable's value.
27.3.2 Easy Customization Interface  Convenient and easy customization of variables.
27.3.3 Editing Variable Values  Examining or editing list of all variables' values.
27.3.4 Local Variables  Per-buffer values of variables.
27.3.5 Local Variables in Files  How files can specify variable values.


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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.


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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  How options are classified in a structure.
27.3.2.2 Changing an Option  How to edit a value and set an option.
27.3.2.3 Customizing Faces  How to edit the attributes of a face.
27.3.2.4 Customizing Specific Items  Making a customization buffer for specific options, faces, or groups.


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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.


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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.


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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]'.


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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.


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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.


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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)


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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.


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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  Defining and running keyboard macros.
27.4.2 Naming and Saving Keyboard Macros  Giving keyboard macros names; saving them in files.
27.4.3 Executing Macros With Variations  Keyboard macros that do different things each use.


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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.


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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.


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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.


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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  Definition of the keymap data structure. Names of Emacs's standard keymaps.
27.5.2 Changing Key Bindings  How to redefine one key's meaning conveniently.
27.5.3 Disabling Commands  Disabling a command means confirmation is required before it can be executed. This is done to protect beginners from surprises.


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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.

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.

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.


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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  
27.5.2.2 Changing Key Bindings Programmatically  
27.5.2.3 Using Strings for Changing Key Bindings  


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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.


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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:

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:

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)


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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


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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.


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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  What the syntax table records for each character.
27.6.2 Altering Syntax Information  How to change the information.


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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 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.


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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.


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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  Syntax of constants in Emacs Lisp.
27.7.2 Init File Examples  How to do some things with an init file.
27.7.3 Terminal-Specific Initialization  Each terminal type can have an init file.


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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.


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27.7.2 Init File Examples

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


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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.


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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


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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.

27.10 Xft Font Customization  


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27.9.1 Customizing Faces

You can change the face of an extent with the functions in this section. All the functions prompt for a face as an argument; use completion for a list of possible values.

M-x invert-face
Swap the foreground and background colors of the given face.
M-x make-face-bold
Make the font of the given face bold. When called from a program, returns nil if this is not possible.
M-x make-face-bold-italic
Make the font of the given face bold italic. When called from a program, returns nil if not possible.
M-x make-face-italic
Make the font of the given face italic. When called from a program, returns nil if not possible.
M-x make-face-unbold
Make the font of the given face non-bold. When called from a program, returns nil if not possible.
M-x make-face-unitalic
Make the font of the given face non-italic. When called from a program, returns nil if not possible.
M-x make-face-larger
Make the font of the given face a little larger. When called from a program, returns nil if not possible.
M-x make-face-smaller
Make the font of the given face a little smaller. When called from a program, returns nil if not possible.
M-x set-face-background
Change the background color of the given face.
M-x set-face-background-pixmap
Change the background pixmap of the given face.
M-x set-face-background-pixmap-file
A simpler version but with filename completion.
M-x set-face-background-placement
Change the placement of the background pixmap of the given face.
M-x set-face-font
Change the font of the given face.
M-x set-face-foreground
Change the foreground color of the given face.
M-x set-face-underline-p
Change whether the given face is underlined.

You can exchange the foreground and background color of the selected face with the function invert-face. If the face does not specify both foreground and background, then its foreground and background are set to the background and foreground of the default face. When calling this from a program, you can supply the optional argument frame to specify which frame is affected; otherwise, all frames are affected.

The work of make-face-bold, make-face-bold-italic, make-face-italic, make-face-unbold, make-face-unitalic functions is affected by face-frob-from-locale-first variable. If it is nil, those functions first try to manipulate device specific data like X font names to obtain the desired font face specification. This may be unsuitable in environments using different font face specifications for different frames, non-Mule environments in particular.

If the variable is non-nil, those functions first try to figure out whether the face font is the same as one of predefined faces: default, bold, italic, bold-italic. If it is the same, then the new face font specification is set to be the same as that of a corresponding predefined face. Thus if the predefined face is set up properly for different frames, the same will hold for the face being changed by the functions. This is the behavior one might desire in non-Mule environments mentioned above: face being changed still looks right in all frames.

How predefined faces might be set up for different frames in such an environments is described in 27.12.4 Face Resources.

You can set the background color of the specified face with the function set-face-background. The argument color should be a string, the name of a color. When called from a program, if the optional frame argument is provided, the face is changed only in that frame; otherwise, it is changed in all frames.

You can set the background pixmap of the specified face with the function set-face-background-pixmap. The pixmap argument name should be a string, the name of a file of pixmap data. The directories listed in the x-bitmap-file-path variable are searched. The bitmap may also be a list of the form (width height data), where width and height are the size in pixels, and data is a string containing the raw bits of the bitmap. If the optional frame argument is provided, the face is changed only in that frame; otherwise, it is changed in all frames.

The variable x-bitmap-file-path takes as a value a list of the directories in which X bitmap files may be found. If the value is nil, the list is initialized from the *bitmapFilePath resource.

If the environment variable XBMLANGPATH is set, then it is consulted before the x-bitmap-file-path variable.

Alternately, you can use a simpler version of set-face-background-pixmap called set-face-background-pixmap-file. This function does not give you as much control on the pixmap instantiator, but provides filename completion.

You can set the placement of the background pixmap of the specified face with the function set-face-background-placement. The placement argument can be either absolute or relative (the default). A relative placement means that the pixmap is attached to the frame and moves with it. An absolute placement means that the pixmap is rather attached to the frame's root window, so that when you move the frame on the screen, it will appear to "slide" on the pixmap. This placement mode can be used to achieve pseudo-translucency for a frame, for example by setting the default face's background pixmap to the root window's one.

You can set the font of the specified face with the function set-face-font. The font argument should be a string, the name of a font. When called from a program, if the optional frame argument is provided, the face is changed only in that frame; otherwise, it is changed in all frames.

The syntax of the font argument varies according to platform. In each of the following syntaxes, the example shows how to specify a 14-point upright bold Courier font.

X11
The X11 syntax is defined by the X Logical Font Descriptor (XLFD) standard. An XLFD contains 14 fields each preceded by a hyphen: foundry, family, weight, slant, swidth, adstyle, pixelsize, pointsize, xresolution, yresolution, spacing, averagewidth, registry, and encoding. It is usually sufficient to specify family, weight, slant, pointsize, registry, and encoding, wildcarding the rest with `*'. If you're not sure what's available, you can wildcard some of the fields usually specified, too. Here's our example font in XLFD syntax: "-*-courier-bold-r-*-*-*-140-*-*-*-*-iso8859-*". The XLFD syntax is also used for GTK+ version 1. XLFD names must be encoded in ISO-8859-1.

Xft
The Xft syntax is defined by the `fontconfig' library @xref{Font Names,,,fontconfig}. It is less a font naming convention than a way to express any arbitrary subset of the font's properties in a syntax that is both human- and machine-readable. A `fontconfig' font name contains the family, a hyphen, and the pointsize, followed by an arbitrary sequence of properties. Each property consists of a colon, a keyword, an equals sign, and the property value. Here's our example font in `fontconfig' syntax: "Courier-14:weight=bold". This syntax admits "style abbreviations" which can be user-defined. A style is a single keyword denoting a sequence of properties. So the example font may be abbreviated to "Courier-14:bold" ("bold" is a standard abbreviation for "weight=bold"). The `fontconfig' syntax is also used for GTK+ version 2. `fontconfig' names must be encoded in UTF-8.

MS-Windows
The MS Windows syntax is superficially similar to that of Xft but actually is more like XLFD. A font name consists of five fields, family, size, slant, weight, and encoding, each expressed as a keyword taking on standardized values (except family, which is just a name). Here's our example font in MS Windows syntax: "Courier:14:Bold:Western".

You can set the foreground color of the specified face with the function set-face-foreground. The argument color should be a string, the name of a color. If the optional frame argument is provided, the face is changed only in that frame; otherwise, it is changed in all frames.

You can set underline the specified face with the function set-face-underline-p. The argument underline-p can be used to make underlining an attribute of the face or not. If the optional frame argument is provided, the face is changed only in that frame; otherwise, it is changed in all frames.


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27.10 Xft Font Customization

This section was written by Stephen Turnbull, and is very much a work in progress. I've tried to provide pointers to as much of the relevant information as possible, but many of the APIs and UIs are in flux, so it seemed more work than it was worth to completely translate the tables of constants, and so on. Feel free to ask for clarifications, etc. Please Cc the XEmacs Beta Testers' mailing list, as that is the issue tracking channel of record, and there are a few others who can answer the questions or improve documentation when I'm not able to respond quickly.

As of mid-2005, we have added support for the `Xft' library, which provides a more robust font configuration mechanism via Keith Packard's `fontconfig' library; improved glyph rendering, including antialiasing, via the `freetype' library; and client-side rendering (saving bandwidth and server memory) via the `XRender extension'.

Font configuration

In XEmacs, font configuration is handled via faces. Currently XEmacs uses a special type of font specifier to map XEmacs locales to font names. Especially under X11, this can cause annoying problems because of the unreliability of X servers' mappings from `XLFD' names to X11 fonts, over which XEmacs has no influence whatsoever. However, the `fontconfig' library which is used with `Xft' provides much more reliable mapping, along with a more reliably parsable naming scheme similar to that used by TrueType fonts on MS Windows and the Macintosh.

fontconfig

Fontconfig is dramatically different from the X model in several ways. In particular, when queried for a font fontconfig always returns a font, whereas X queries may return "not found." However, the font returned need not be anything like the desired font. This is not really a problem in practice, because users generally have a pretty good idea of what fonts are available on their display. However, users should be aware that as of XEmacs 21.5.26 the font selection internals have not been revised to account for this radically different model, so some surprising results are possible.

From the user's point of view, `fontconfig' provides a naming convention which is precise, accurate, and convenient. Precision means that all properties available in the programming API can be individually specified. Accuracy means that the truename of the font is exactly the list of all properties specified by the font. Thus, the anomalies that occur with XLFDs on many servers (including modern Linux distributions with XFree86 or X.org servers) cannot occur. Convenience is subjective, of course. However, `fontconfig' provides a configuration system which (1) explicitly specifies the defaults and substitutions that will be made in processing user queries, (2) allows the user to specify search configuration, abbreviations, substitutions, and defaults that override the system's, in the same format as used by system files, and (3) allows flexible aliases that can resolve to any of several actual fonts depending on which fonts are installed.

Further, a standard minimal configuration is defined that ensures that at least the serif, sans-serif, and monospace font aliases are available on all `fontconfig' systems.

fontconfig font names

`fontconfig' font names are very regular, and constitute a precise and extensible specification of a font's properties.

The basic `fontconfig' font name has three components: the font family name, the size, and a list of named attribute fields. All attribute names and values are strings encoded in Unicode UTF-8, or decimal numbers with optional decimal point and fraction. The characters `-', `:', `,', `=', and `\' are syntactically significant to `fontconfig'. They may be used in font name components by the familiar mechanism of backslash escaping. This simply removes any special meaning from the following character. It is always safe to use an escape even if it is not needed.

Most string values are case-insensitive, but this is attribute-specific.

The font family name is an arbitrary string, which may contain any character, including spaces, hyphens, and commas. Don't forget to escape hyphens, colons, commas, and backslashes!

The size is a decimal number with optional decimal point and fractional part. It is interpreted as point size.

A named attribute field is a key-value pair separated by an equal sign. Some attributes have predefined semantics. (These include such familiar attributes as `slant' and `dpi' -- note that `fontconfig' does not distinguish between vertical and horizontal resolution!

The basic syntax of a font name is simple and regular. The font family name comes first, followed by a hyphen and the size, followed by a list of named attribute fields, each introduced by a colon:

 
font family name-size:key1=value1:key2=value2...

There are four extensions to the basic syntax. First, all of the fields are optional. If size is omitted, the hyphen should be omitted as well. There should never be a trailing colon. Note that `fontconfig' does not interpret an omitted field as "default to current." `fontconfig' does not have access to that context. Instead, omitted fields are filled in according to a set of defaults specified in the system `fonts.conf' file and in the user's `.fonts.cont' file. The user's configuration gets precedence, of course.

The second is that the font family name, the size, and the value component of a named attribute field may be a comma-separated list of values. This is called a pattern. In queries, `fontconfig' tries to match each entry in the list in order. (I suspect that order of attributes is also significant. I.e., font family always gets highest precedence, followed by size, followed by the remaining named attributes. Testing and reports to the XEmacs Beta Testers mailing list are very welcome!)

The third is the definition of constants to represent numerical values. For example, both `slant' and `weight' are defined as integer attributes, but the magnitudes are arbitrary; only the ordering and relative distances are useful. ("Relative distance" is used to implement the concept that although strictly speaking italic and oblique are different faces, most users don't know the difference, and even professional typographers would agree that they are much closer to each other than either is to roman.) So constants like `roman' (0) and `italic' (100) are defined for `slant', and `medium' (100) and `bold' (200) are defined for `weight'.

The fourth is that a style may be defined as an alias for an instance of a named attribute field, that is, specifying both key and value. The styles `bold', an alias for `weight=200', and `italic', an alias for `slant=100', are commonly used.

Styles and constants can be defined by the application. XEmacs currently defines none, but suggestions are welcome if some convenient alias is lacking from `fontconfig'. Note that we will not provide additional aliases where standard ones exist, e.g., `heavy' as an additional alias for `bold' would almost certainly be rejected. These cause more confusion than they are worth, and would decrease portability of user specifications to other applications.

(Attributes can also be defined, but they must be implemented by the fonts to be useful. Until XEmacs provides its own fonts with non-standardized attributes, this is not useful.)

Here are some examples of font names and query patterns:

 
Times-12                    12-point Times Roman
Times-12:bold               12-point Times Bold
Courier:italic              Courier Italic in the default size
Monospace:matrix=1 .1 0 1   The user's preferred monospace font
                            with artificial obliquing
Mikachan\-PB-16             16-point Mikachan-PB
LucidaTypewriter,Courier-9  9-point LucidaTypewriter if available,
                            otherwise 9-point Courier

Note how styles are used in the second and third examples, how `matrix' has a complex value containing spaces, and the escaped hyphen in the font family name `Mikachan\-PB'.

Here is a (somewhat outdated) list of current standard named attributes:

 
Property        CPP symbol      Type    Description

family          FC_FAMILY       String  Font family name
style           FC_STYLE        String  Font style. Overrides weight and slant
slant           FC_SLANT        Int     Italic, oblique or roman
weight          FC_WEIGHT       Int     Light, medium, demibold, bold or black
size            FC_SIZE         Double  Point size
aspect          FC_ASPECT       Double  Stretch glyphs horizontally, then hint
pixelsize       FC_PIXEL_SIZE   Double  Pixel size
spacing         FC_SPACING      Int     Proportional, monospace or charcell
foundry         FC_FOUNDRY      String  Font foundry name
antialias       FC_ANTIALIAS    Bool    Should glyphs be antialiased?
hinting         FC_HINTING      Bool    Should the rasterizer use hinting?
verticallayout  FC_VERTICAL_LAYOUT Bool Use vertical layout
autohint        FC_AUTOHINT     Bool    Use autohinter instead of normal hinter
globaladvance   FC_GLOBAL_ADVANCE Bool  Use font global advance data
file            FC_FILE         String  The filename holding the font
index           FC_INDEX        Int     The index of the font within the file
ftface          FC_FT_FACE      FT_Face Use the specified FreeType face object
rasterizer      FC_RASTERIZER   String  Which rasterizer is in use
outline         FC_OUTLINE      Bool    Whether the glyphs are outlines
scalable        FC_SCALABLE     Bool    Whether glyphs can be scaled
scale           FC_SCALE        Double  Point->pixel conversion scale factor
dpi             FC_DPI          Double  Target dots per inch
rgba            FC_RGBA         Int     unknown, rgb, bgr, vrgb, vbgr, none
                                        - subpixel geometry
source		FC_SOURCE	String  X11, freetype
minspace        FC_MINSPACE     Bool    Eliminate leading from line spacing
charset         FC_CHARSET      CharSet Unicode chars encoded by the font
lang            FC_LANG         String  List of RFC-3066-style languages
                                        this font supports
fontversion	FC_FONTVERSION  Int     From 'head' table

Here is a list of current standard constants:

 
Constant        Property        CPP symbol

light           weight          FC_WEIGHT_LIGHT
medium          weight          FC_WEIGHT_MEDIUM
demibold        weight          FC_WEIGHT_DEMIBOLD
bold            weight          FC_WEIGHT_BOLD
black           weight          FC_WEIGHT_BLACK
roman           slant           FC_SLANT_ROMAN
italic          slant           FC_SLANT_ITALIC
oblique         slant           FC_SLANT_OBLIQUE
proportional    spacing         FC_PROPORTIONAL
mono            spacing         FC_MONO
charcell        spacing         FC_CHARCELL
unknown         rgba            FC_RGBA_UNKNOWN
rgb             rgba            FC_RGBA_RGB
bgr             rgba            FC_RGBA_BGR
vrgb            rgba            FC_RGBA_VRGB
vbgr            rgba            FC_RGBA_VBGR
none            rgba            FC_RGBA_NONE

Note that this is the `fontconfig' API list; you can expect that XEmacs will define corresponding keywords by substituting `:' for the leading `FC_', `-' for `_', removing the key of the attribute if present, and lowercasing the name. Thus `FC_WEIGHT_BOLD' becomes `:bold'. M-x apropos RET fc-.*-mapping will give a list of variables each of which lists such keywords and their meanings.

Font menus

The `Options->Font' and `Options->Font Sizes' menus are broken, by design, not just by `Xft'. The problem is that many fonts are unavailable because they don't match the current size--which is very strange, since `Xft' fonts are of course scalable. But the whole idea of requiring that the font match the size is strange. And the `Options->Font Weights' menu is just disabled, and has been for eons.

X resources

Currently there are four treatments of font resources. There are the `XEmacs.face.attributeFont' resources used to set a single global font specification. In the widgets, some (still) have a `font' resource using the automatic `Xt' resource conversion to X's `FontStruct', some have separate `font' and `xftFont' resources with the former automatically converted to `FontStruct' by `Xt' and the latter left as a string, to be converted to a fontconfig `FcPattern' by `FcParseName' later, and some have a single `font' resource which is converted to `FontStruct' by `Xt' or the latter left as a string, depending on whether `Xft' was enabled by `configure' or not.

Eventually these should be converted to use the face approach, perhaps with some way to set specifications for individual widgets, frames, or buffers. This will require some careful design work to incorporate face support in the widgets. Stephen's current thinking is that XEmacs should just accept any or all of `font', `fontSet', and `fontList' resources, treat them all as lists of font names, either `XLFD'- or `fontconfig'-style, parse them ourselves (ie, not use the `Xt' resource manager), and add them to font specifiers as appropriate. But this will require a bit of thought to obey POLA vis-a-vis usual `Xt' conventions.

Specifiers, charsets, and languages

Traditionally Mule uses a rather rigid and low-level abstraction, the charset, to characterize font repertoires. Unfortunately, support for a given charset is generally neither necessary nor sufficient to support a language. Worse, in XEmacs's current implementation Xft doesn't help much. Instead you need to add the fonts for different charsets to the font specifier in the right order.

There currently is no explicit way to specify that a particular font be used only for a given language. However, since many fonts support only a limited repertoire such as ISO 8859/1, you can use the precedence of specifications for a given specifier locale to get something of this effect for non-Latin character sets. This will normally work rather poorly for multiple Latin character sets, however, because the repertoires tend to have large amounts of overlap. Support for specifying font by language as well as by character set is planned.

Because fonts supporting other languages tend to support English as well, if you want to use one font for English and another for the other language, you must use the append method when adding font specifications for the other language.

However, this simple method leaves you with a problem if you want to change the other language's font: you have to remove the existing specification so it won't shadow the new one when you append.

In order to provide a convenient way to change "other-language fonts", I use remove-tag-set-append and define-specifier-tag like this:

 
(define-specifier-tag 'lang-ja)
;; No, I don't try to do real work with this font!  But it makes it
;; obvious that I got the requested font.  :-)
(set-face-font 'default "AirCut-14")
(set-face-font 'default "Kochi Mincho-14" nil '(lang-ja) 'append)
;; Oops, too sober.  Try something to match AirCut.
(set-face-font 'default "Mikachan-14"
               nil '(lang-ja) 'remove-tag-set-append)

The only way to configure widget fonts at the present time is to use X resources (or hack the source and rebuild). Currently supported widgets are

Here are the resources I use. Warning: This interface will change. Pay attention to beta announcements, and complain loudly if changes aren't documented here! The tab control and menubar have separate Font and FcFontName resources, and use the X resource manager to instantiate a FontStruct from the Font resource. There is no converter facility for FcFontName yet, and creating one that handles both FontStruct and XftFont depending on XEmacs's configuration and the font name seems error-prone at best. Probably we will use a simple string representation for this resource, and convert to a face in XEmacs rather than a font in Xt/Xft. (The older XftFont resource is deprecated. There is code intended to implement backward compatibility, but there are repots that it doesn't work properly.)

 
XEmacs*Tabs.fcFontName: Bitstream Vera Sans-16
XEmacs*menubar*fcFontName: Bitstream Vera Sans-16
XEmacs.modeline.attributeFont: Bitstream Charter-16
XEmacs.default.attributeFont: Bitstream Vera Sans Mono-16
I highly recommend use of a proportional font in the modeline because it allows a lot more text to fit there.

Known Problems

Options->Font
Options->Font Size
These menus don't work. All fonts are greyed out. All sizes are available, but many (most?) faces don't change size, in particular, `default' does not.

Antialiased text bleeding outside of reported extent
This is most obvious with the underscore character in that font, and with cursors. The bottom of the underscore is antialiased, and insertions or deletions in the same line before the underscore leave a series of "phantom" underlines.

I think this is probably an Xft bug, but I'm not sure.

Variables Used with Xft and Fontconfig

Variable: xft-debug-level

Level of debugging messages to issue to stderr for Xft. A nonnegative integer. Set to 0 to suppress all warnings. Default is 1 to ensure a minimum of debugging output at initialization. Higher levels give more information.

Variable: xft-version

The major version number of the Xft library compiled with.

Variable: xft-xlfd-font-regexp

Regular expression matching XLFD font names.


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27.11 Frame Components

You can control the presence and position of most frame components, such as the menubar, toolbars, and gutters.

This section is not written yet. Try the Lisp Reference Manual: @xref{Menubar,,,lispref,}, @xref{Toolbar Intro,,,lispref,}, and @xref{Gutter Intro,,,lispref,}.


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27.12 X Resources

Historically, XEmacs used the X resource application class `Emacs' for its resources. Unfortunately, GNU Emacs's usage of resources has evolved differently from XEmacs's, and especially in the case of fonts semantics are not compatible between the two Emacsen. Thus, sharing of the application class can easily lead to trouble.

XEmacs now uses the X resource application class `XEmacs'. Versions since 21.5.21 do this unconditionally. To attempt to maintain some backward compatibility, previous versions checked the X resource database for resources starting in `XEmacs', and if none were found, `Emacs' was used. This behavior is likely to be obsoleted, so you should move your X resources to using the `XEmacs' class. In the short term, to stay with the old behavior, start XEmacs with the environment variable USE_EMACS_AS_DEFAULT_APPLICATION_CLASS set to some non-empty value; this will restore the pre-21.5.21 behavior. Lisp programs can examine the variable x-emacs-application-class to determine which is being used in the running application.

The examples in this section assume the application class is `XEmacs'.

Most of XEmacs's resources are set per-frame. Each XEmacs frame can have its own name or the same name as another, depending on the name passed to the make-frame function. Up until 21.5.21, the default frame name was `emacs'; since then, it has been `XEmacs', but in the short term the old default can be restored by the USE_EMACS_AS_DEFAULT_APPLICATION_CLASS environment variable mentioned above. See the docstring for the Lisp variable `default-frame-name'.

You can specify resources for all frames with the syntax:

 
XEmacs*parameter: value

or

 
XEmacs*EmacsFrame.parameter:value

You can specify resources for a particular frame with the syntax:

 
XEmacs*FRAME-NAME.parameter: value

27.12.1 Geometry Resources  Controlling the size and position of frames.
27.12.2 Iconic Resources  Controlling whether frames come up iconic.
27.12.3 Resource List  List of resources settable on a frame or device.
27.12.4 Face Resources  Controlling faces using resources.
27.12.5 Widgets  The widget hierarchy for XEmacs.
27.12.6 Menubar Resources  Specifying resources for the menubar.


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27.12.1 Geometry Resources

To make the default size of all XEmacs frames be 80 columns by 55 lines, do this:

 
XEmacs*EmacsFrame.geometry: 80x55

To set the geometry of a particular frame named `fred', do this:

 
XEmacs*fred.geometry: 80x55

Important! Do not use the following syntax:

 
XEmacs*geometry: 80x55

You should never use *geometry with any X application. It does not say "make the geometry of XEmacs be 80 columns by 55 lines." It really says, "make XEmacs and all subwindows thereof be 80x55 in whatever units they care to measure in." In particular, that is both telling the XEmacs text pane to be 80x55 in characters, and telling the menubar pane to be 80x55 pixels, which is surely not what you want.

As a special case, this geometry specification also works (and sets the default size of all XEmacs frames to 80 columns by 55 lines):

 
XEmacs.geometry: 80x55

since that is the syntax used with most other applications (since most other applications have only one top-level window, unlike XEmacs). In general, however, the top-level shell (the unmapped ApplicationShell widget named `XEmacs' that is the parent of the shell widgets that actually manage the individual frames) does not have any interesting resources on it, and you should set the resources on the frames instead.

The -geometry command-line argument sets only the geometry of the initial frame created by XEmacs.

A more complete explanation of geometry-handling is

This is rather complicated, but it does seem to provide the most intuitive behavior with respect to the default sizes and positions of frames created in various ways.


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27.12.2 Iconic Resources

Analogous to -geometry, the -iconic command-line option sets the iconic flag of the ApplicationShell (XEmacs.iconic) and always applies to the first frame created regardless of its name. However, it is possible to set the iconic flag on particular frames (by name) by using the XEmacs*FRAME-NAME.iconic resource.


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27.12.3 Resource List

XEmacs frames accept the following resources:

geometry (class Geometry): string
Initial geometry for the frame. See section 27.12.1 Geometry Resources, for a complete discussion of how this works.

iconic (class Iconic): boolean
Whether this frame should appear in the iconified state.

internalBorderWidth (class InternalBorderWidth): int
How many blank pixels to leave between the text and the edge of the window.

interline (class Interline): int
How many pixels to leave between each line (may not be implemented).

menubar (class Menubar): boolean
Whether newly-created frames should initially have a menubar. Set to true by default.

initiallyUnmapped (class InitiallyUnmapped): boolean
Whether XEmacs should leave the initial frame unmapped when it starts up. This is useful if you are starting XEmacs as a server (e.g. in conjunction with gnuserv or the external client widget). You can also control this with the -unmapped command-line option.

barCursor (class BarColor): boolean
Whether the cursor should be displayed as a bar, or the traditional box.

cursorColor (class CursorColor): color-name
The color of the text cursor.

scrollBarWidth (class ScrollBarWidth): integer
How wide the vertical scrollbars should be, in pixels; 0 means no vertical scrollbars. You can also use a resource specification of the form *scrollbar.width, or the usual toolkit scrollbar resources: *XmScrollBar.width (Motif), *XlwScrollBar.width (Lucid), or *Scrollbar.thickness (Athena). We don't recommend that you use the toolkit resources, though, because they're dependent on how exactly your particular build of XEmacs was configured.

scrollBarHeight (class ScrollBarHeight): integer
How high the horizontal scrollbars should be, in pixels; 0 means no horizontal scrollbars. You can also use a resource specification of the form *scrollbar.height, or the usual toolkit scrollbar resources: *XmScrollBar.height (Motif), *XlwScrollBar.height (Lucid), or *Scrollbar.thickness (Athena). We don't recommend that you use the toolkit resources, though, because they're dependent on how exactly your particular build of XEmacs was configured.

scrollBarPlacement (class ScrollBarPlacement): string
Where the horizontal and vertical scrollbars should be positioned. This should be one of the four strings `BOTTOM_LEFT', `BOTTOM_RIGHT', `TOP_LEFT', and `TOP_RIGHT'. Default is `BOTTOM_RIGHT' for the Motif and Lucid scrollbars and `BOTTOM_LEFT' for the Athena scrollbars.

topToolBarHeight (class TopToolBarHeight): integer
bottomToolBarHeight (class BottomToolBarHeight): integer
leftToolBarWidth (class LeftToolBarWidth): integer
rightToolBarWidth (class RightToolBarWidth): integer
Height and width of the four possible toolbars.

topToolBarShadowColor (class TopToolBarShadowColor): color-name
bottomToolBarShadowColor (class BottomToolBarShadowColor): color-name
Color of the top and bottom shadows for the toolbars. NOTE: These resources do not have anything to do with the top and bottom toolbars (i.e. the toolbars at the top and bottom of the frame)! Rather, they affect the top and bottom shadows around the edges of all four kinds of toolbars.

topToolBarShadowPixmap (class TopToolBarShadowPixmap): pixmap-name
bottomToolBarShadowPixmap (class BottomToolBarShadowPixmap): pixmap-name
Pixmap of the top and bottom shadows for the toolbars. If set, these resources override the corresponding color resources. NOTE: These resources do not have anything to do with the top and bottom toolbars (i.e. the toolbars at the top and bottom of the frame)! Rather, they affect the top and bottom shadows around the edges of all four kinds of toolbars.

toolBarShadowThickness (class ToolBarShadowThickness): integer
Thickness of the shadows around the toolbars, in pixels.

visualBell (class VisualBell): boolean
Whether XEmacs should flash the screen rather than making an audible beep.

bellVolume (class BellVolume): integer
Volume of the audible beep.

useBackingStore (class UseBackingStore): boolean
Whether XEmacs should set the backing-store attribute of the X windows it creates. This increases the memory usage of the X server but decreases the amount of X traffic necessary to update the screen, and is useful when the connection to the X server goes over a low-bandwidth line such as a modem connection.

XEmacs devices accept the following resources:

textPointer (class Cursor): cursor-name
The cursor to use when the mouse is over text. This resource is used to initialize the variable x-pointer-shape.

selectionPointer (class Cursor): cursor-name
The cursor to use when the mouse is over a selectable text region (an extent with the `highlight' property; for example, an Info cross-reference). This resource is used to initialize the variable x-selection-pointer-shape.

spacePointer (class Cursor): cursor-name
The cursor to use when the mouse is over a blank space in a buffer (that is, after the end of a line or after the end-of-file). This resource is used to initialize the variable x-nontext-pointer-shape.

modeLinePointer (class Cursor): cursor-name
The cursor to use when the mouse is over a modeline. This resource is used to initialize the variable x-mode-pointer-shape.

gcPointer (class Cursor): cursor-name
The cursor to display when a garbage-collection is in progress. This resource is used to initialize the variable x-gc-pointer-shape.

scrollbarPointer (class Cursor): cursor-name
The cursor to use when the mouse is over the scrollbar. This resource is used to initialize the variable x-scrollbar-pointer-shape.

pointerColor (class Foreground): color-name
pointerBackground (class Background): color-name
The foreground and background colors of the mouse cursor. These resources are used to initialize the variables x-pointer-foreground-color and x-pointer-background-color.


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27.12.4 Face Resources

The attributes of faces are also per-frame. They can be specified as:

 
XEmacs.FACE_NAME.parameter: value

or

 
XEmacs*FRAME_NAME.FACE_NAME.parameter: value

Faces accept the following resources:

attributeFont (class AttributeFont): font-name
The font of this face.

attributeForeground (class AttributeForeground): color-name
attributeBackground (class AttributeBackground): color-name
The foreground and background colors of this face.

attributeBackgroundPixmap (class AttributeBackgroundPixmap): file-name
The name of an XBM file (or XPM file, if your version of XEmacs supports XPM), to use as a background stipple.

attributeUnderline (class AttributeUnderline): boolean
Whether text in this face should be underlined.

All text is displayed in some face, defaulting to the face named default. To set the font of normal text, use XEmacs*default.attributeFont. To set it in the frame named fred, use XEmacs*fred.default.attributeFont.

These are the names of the predefined faces:

default
Everything inherits from this.

bold
If this is not specified in the resource database, XEmacs tries to find a bold version of the font of the default face.

italic
If this is not specified in the resource database, XEmacs tries to find an italic version of the font of the default face.

bold-italic
If this is not specified in the resource database, XEmacs tries to find a bold-italic version of the font of the default face.

modeline
This is the face that the modeline is displayed in. If not specified in the resource database, it is determined from the default face by reversing the foreground and background colors.

highlight
This is the face that highlighted extents (for example, Info cross-references and possible completions, when the mouse passes over them) are displayed in.

left-margin
right-margin
These are the faces that the left and right annotation margins are displayed in.

zmacs-region
This is the face that mouse selections are displayed in.

isearch
This is the face that the matched text being searched for is displayed in.

info-node
This is the face of info menu items. If unspecified, it is copied from bold-italic.

info-xref
This is the face of info cross-references. If unspecified, it is copied from bold. (Note that, when the mouse passes over a cross-reference, the cross-reference's face is determined from a combination of the info-xref and highlight faces.)

Other packages might define their own faces; to see a list of all faces, use any of the interactive face-manipulation commands such as set-face-font and type `?' when you are prompted for the name of a face.

If the bold, italic, and bold-italic faces are not specified in the resource database, then XEmacs attempts to derive them from the font of the default face. It can only succeed at this if you have specified the default font using the XLFD (X Logical Font Description) format, which looks like

 
*-courier-medium-r-*-*-*-120-*-*-*-*-*-*

All X fonts can be referred to via XLFD-style names, and you should use those forms. See the man pages for `X(1)', `xlsfonts(1)', and `xfontsel(1)'.

If you use any of the other, less strict font name formats, some of which look like

 
lucidasanstypewriter-12
fixed
9x13

then XEmacs won't be able to guess the names of the bold and italic versions, and on a build with internationalization support, it will refuse to use them. (Since only the XLFD form includes information as to which character set the font coverage.)

If it is very important to you to use the short form names, you can override this for ASCII, and for ASCII alone, by passing the `FORCE' argument to `set-charset-registries', and specifying an empty string as one of the charset registries.


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27.12.5 Widgets

There are several structural widgets between the terminal EmacsFrame widget and the top level ApplicationShell; the exact names and types of these widgets change from release to release (for example, they changed between 19.8 and 19.9, 19.9 and 19.10, and 19.10 and 19.12) and are subject to further change in the future, so you should avoid mentioning them in your resource database. The above-mentioned syntaxes should be forward- compatible. As of 19.13, the exact widget hierarchy is as follows:

 
INVOCATION-NAME            "shell"       "container"     FRAME-NAME
x-emacs-application-class  "EmacsShell"  "EmacsManager"  "EmacsFrame"

where INVOCATION-NAME is the terminal component of the name of the XEmacs executable (usually `xemacs'), and `x-emacs-application-class' is generally `XEmacs'.


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27.12.6 Menubar Resources

As the menubar is implemented as a widget which is not a part of XEmacs proper, it does not use the face mechanism for specifying fonts and colors: It uses whatever resources are appropriate to the type of widget which is used to implement it.

If XEmacs was compiled to use only the Lucid Motif-lookalike menu widgets, then one way to specify the font of the menubar would be

 
XEmacs*menubar*font: *-courier-medium-r-*-*-*-120-*-*-*-*-*-*

If both the Lucid Motif-lookalike menu widgets and X Font Sets are configured to allow multilingual menubars, then one uses

 
*menubar*FontSet:       -*-helvetica-bold-r-*-*-*-120-*-*-*-*-iso8859-*, \
                        -*-*-*-*-*-*-*-120-*-jisx0208.1983-0

That would specify fonts for a Japanese menubar. Specifying only one XLFD is acceptable; specifying more than one for a given registry (language) is also allowed. When X Font Sets are configured, some .font resources (eg, menubars) are ignored in favor of the corresponding .fontSet resources.

If the Motif library is being used, then one would have to use

 
XEmacs*menubar*fontList: *-courier-medium-r-*-*-*-120-*-*-*-*-*-*

because the Motif library uses the fontList resource name instead of font, which has subtly different semantics.

The same is true of the scrollbars: They accept whichever resources are appropriate for the toolkit in use.


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27.13 Quitting and Aborting

C-g
Quit. Cancel running or partially typed command.
C-]
Abort innermost recursive editing level and cancel the command which invoked it (abort-recursive-edit).
M-x top-level
Abort all recursive editing levels that are currently executing.
C-x u
Cancel an already-executed command, usually (undo).

There are two ways of cancelling commands which are not finished executing: quitting with C-g, and aborting with C-] or M-x top-level. Quitting is cancelling a partially typed command or one which is already running. Aborting is getting out of a recursive editing level and cancelling the command that invoked the recursive edit.

Quitting with C-g is used for getting rid of a partially typed command or a numeric argument that you don't want. It also stops a running command in the middle in a relatively safe way, so you can use it if you accidentally start executing a command that takes a long time. In particular, it is safe to quit out of killing; either your text will all still be there, or it will all be in the kill ring (or maybe both). Quitting an incremental search does special things documented under searching; in general, it may take two successive C-g characters to get out of a search. C-g works by setting the variable quit-flag to t the instant C-g is typed; Emacs Lisp checks this variable frequently and quits if it is non-nil. C-g is only actually executed as a command if it is typed while Emacs is waiting for input.

If you quit twice in a row before the first C-g is recognized, you activate the "emergency escape" feature and return to the shell. See section 27.14.5 Emergency Escape.

You can use C-] (abort-recursive-edit) to get out of a recursive editing level and cancel the command which invoked it. Quitting with C-g does not do this, and could not do this because it is used to cancel a partially typed command within the recursive editing level. Both operations are useful. For example, if you are in the Emacs debugger (see section 22.5 The Emacs-Lisp Debugger) and have typed C-u 8 to enter a numeric argument, you can cancel that argument with C-g and remain in the debugger.

The command M-x top-level is equivalent to "enough" C-] commands to get you out of all the levels of recursive edits that you are in. C-] only gets you out one level at a time, but M-x top-level goes out all levels at once. Both C-] and M-x top-level are like all other commands and unlike C-g in that they are effective only when Emacs is ready for a command. C-] is an ordinary key and has its meaning only because of its binding in the keymap. See section 26.10 Recursive Editing Levels.

C-x u (undo) is not strictly speaking a way of cancelling a command, but you can think of it as cancelling a command already finished executing. See section 5. Undoing Changes.


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27.14 Dealing With Emacs Trouble

This section describes various conditions in which Emacs fails to work, and how to recognize them and correct them.

27.14.1 Recursive Editing Levels  `[...]' in mode line around the parentheses.
27.14.2 Garbage on the Screen  Garbage on the screen.
27.14.3 Garbage in the Text  Garbage in the text.
27.14.4 Spontaneous Entry to Incremental Search  Spontaneous entry to incremental search.
27.14.5 Emergency Escape  Emergency escape--- What to do if Emacs stops responding.
27.14.6 Help for Total Frustration  When you are at your wits' end.


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27.14.1 Recursive Editing Levels

Recursive editing levels are important and useful features of Emacs, but they can seem like malfunctions to the user who does not understand them.

If the mode line has square brackets `[...]' around the parentheses that contain the names of the major and minor modes, you have entered a recursive editing level. If you did not do this on purpose, or if you don't understand what that means, you should just get out of the recursive editing level. To do so, type M-x top-level. This is called getting back to top level. See section 26.10 Recursive Editing Levels.


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27.14.2 Garbage on the Screen

If the data on the screen looks wrong, the first thing to do is see whether the text is actually wrong. Type C-l, to redisplay the entire screen. If the text appears correct after this, the problem was entirely in the previous screen update.

Display updating problems often result from an incorrect termcap entry for the terminal you are using. The file `etc/TERMS' in the Emacs distribution gives the fixes for known problems of this sort. `INSTALL' contains general advice for these problems in one of its sections. Very likely there is simply insufficient padding for certain display operations. To investigate the possibility that you have this sort of problem, try Emacs on another terminal made by a different manufacturer. If problems happen frequently on one kind of terminal but not another kind, the real problem is likely to be a bad termcap entry, though it could also be due to a bug in Emacs that appears for terminals that have or lack specific features.


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27.14.3 Garbage in the Text

If C-l shows that the text is wrong, try undoing the changes to it using C-x u until it gets back to a state you consider correct. Also try C-h l to find out what command you typed to produce the observed results.

If a large portion of text appears to be missing at the beginning or end of the buffer, check for the word `Narrow' in the mode line. If it appears, the text is still present, but marked off-limits. To make it visible again, type C-x n w. See section 26.8 Narrowing.


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27.14.4 Spontaneous Entry to Incremental Search

If Emacs spontaneously displays `I-search:' at the bottom of the screen, it means that the terminal is sending C-s and C-q according to the poorly designed xon/xoff "flow control" protocol. You should try to prevent this by putting the terminal in a mode where it will not use flow control, or by giving it enough padding that it will never send a C-s. If that cannot be done, you must tell Emacs to expect flow control to be used, until you can get a properly designed terminal.

Information on how to do these things can be found in the file `INSTALL' in the Emacs distribution.


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27.14.5 Emergency Escape

Because at times there have been bugs causing Emacs to loop without checking quit-flag, a special feature causes Emacs to be suspended immediately if you type a second C-g while the flag is already set, so you can always get out of XEmacs. Normally Emacs recognizes and clears quit-flag (and quits!) quickly enough to prevent this from happening.

When you resume Emacs after a suspension caused by multiple C-g, it asks two questions before going back to what it had been doing:

 
Auto-save? (y or n)
Abort (and dump core)? (y or n)

Answer each one with y or n followed by RET.

Saying y to `Auto-save?' causes immediate auto-saving of all modified buffers in which auto-saving is enabled.

Saying y to `Abort (and dump core)?' causes an illegal instruction to be executed, dumping core. This is to enable a wizard to figure out why Emacs was failing to quit in the first place. Execution does not continue after a core dump. If you answer n, execution does continue. With luck, Emacs will ultimately check quit-flag and quit normally. If not, and you type another C-g, it is suspended again.

If Emacs is not really hung, but is just being slow, you may invoke the double C-g feature without really meaning to. In that case, simply resume and answer n to both questions, and you will arrive at your former state. Presumably the quit you requested will happen soon.

The double-C-g feature may be turned off when Emacs is running under a window system, since the window system always enables you to kill Emacs or to create another window and run another program.


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27.14.6 Help for Total Frustration

If using Emacs (or something else) becomes terribly frustrating and none of the techniques described above solve the problem, Emacs can still help you.

First, if the Emacs you are using is not responding to commands, type C-g C-g to get out of it and then start a new one.

Second, type M-x doctor RET.

The doctor will make you feel better. Each time you say something to the doctor, you must end it by typing RET RET. This lets the doctor know you are finished.


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27.15 Reporting Bugs

Sometimes you will encounter a bug in Emacs. Although we cannot promise we can or will fix the bug, and we might not even agree that it is a bug, we want to hear about bugs you encounter in case we do want to fix them.

To make it possible for us to fix a bug, you must report it. In order to do so effectively, you must know when and how to do it.


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27.15.1 When Is There a Bug

If Emacs executes an illegal instruction, or dies with an operating system error message that indicates a problem in the program (as opposed to something like "disk full"), then it is certainly a bug.

If Emacs updates the display in a way that does not correspond to what is in the buffer, then it is certainly a bug. If a command seems to do the wrong thing but the problem corrects itself if you type C-l, it is a case of incorrect display updating.

Taking forever to complete a command can be a bug, but you must make certain that it was really Emacs's fault. Some commands simply take a long time. Type C-g and then C-h l to see whether the input Emacs received was what you intended to type; if the input was such that you know it should have been processed quickly, report a bug. If you don't know whether the command should take a long time, find out by looking in the manual or by asking for assistance.

If a command you are familiar with causes an Emacs error message in a case where its usual definition ought to be reasonable, it is probably a bug.

If a command does the wrong thing, that is a bug. But be sure you know for certain what it ought to have done. If you aren't familiar with the command, or don't know for certain how the command is supposed to work, then it might actually be working right. Rather than jumping to conclusions, show the problem to someone who knows for certain.

Finally, a command's intended definition may not be best for editing with. This is a very important sort of problem, but it is also a matter of judgment. Also, it is easy to come to such a conclusion out of ignorance of some of the existing features. It is probably best not to complain about such a problem until you have checked the documentation in the usual ways, feel confident that you understand it, and know for certain that what you want is not available. If you are not sure what the command is supposed to do after a careful reading of the manual, check the index and glossary for any terms that may be unclear. If you still do not understand, this indicates a bug in the manual. The manual's job is to make everything clear. It is just as important to report documentation bugs as program bugs.

If the online documentation string of a function or variable disagrees with the manual, one of them must be wrong, so report the bug.


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27.15.2 How to Report a Bug

When you decide that there is a bug, it is important to report it and to report it in a way which is useful. What is most useful is an exact description of what commands you type, starting with the shell command to run Emacs, until the problem happens. Always include the version number of Emacs that you are using; type M-x emacs-version to print this.

The most important principle in reporting a bug is to report facts, not hypotheses or categorizations. It is always easier to report the facts, but people seem to prefer to strain to posit explanations and report them instead. If the explanations are based on guesses about how Emacs is implemented, they will be useless; we will have to try to figure out what the facts must have been to lead to such speculations. Sometimes this is impossible. But in any case, it is unnecessary work for us.

For example, suppose that you type C-x C-f /glorp/baz.ugh RET, visiting a file which (you know) happens to be rather large, and Emacs prints out `I feel pretty today'. The best way to report the bug is with a sentence like the preceding one, because it gives all the facts and nothing but the facts.

Do not assume that the problem is due to the size of the file and say, "When I visit a large file, Emacs prints out `I feel pretty today'." This is what we mean by "guessing explanations". The problem is just as likely to be due to the fact that there is a `z' in the file name. If this is so, then when we got your report, we would try out the problem with some "large file", probably with no `z' in its name, and not find anything wrong. There is no way in the world that we could guess that we should try visiting a file with a `z' in its name.

Alternatively, the problem might be due to the fact that the file starts with exactly 25 spaces. For this reason, you should make sure that you inform us of the exact contents of any file that is needed to reproduce the bug. What if the problem only occurs when you have typed the C-x a l command previously? This is why we ask you to give the exact sequence of characters you typed since starting to use Emacs.

You should not even say "visit a file" instead of C-x C-f unless you know that it makes no difference which visiting command is used. Similarly, rather than saying "if I have three characters on the line," say "after I type RET A B C RET C-p," if that is the way you entered the text.

If you are not in Fundamental mode when the problem occurs, you should say what mode you are in.

If the manifestation of the bug is an Emacs error message, it is important to report not just the text of the error message but a backtrace showing how the Lisp program in Emacs arrived at the error. To make the backtrace, you must execute the Lisp expression (setq debug-on-error t) before the error happens (that is to say, you must execute that expression and then make the bug happen). This causes the Lisp debugger to run (see section 22.5 The Emacs-Lisp Debugger). The debugger's backtrace can be copied as text into the bug report. This use of the debugger is possible only if you know how to make the bug happen again. Do note the error message the first time the bug happens, so if you can't make it happen again, you can report at least that.

Check whether any programs you have loaded into the Lisp world, including your init file, set any variables that may affect the functioning of Emacs. See section 27.7 The Init File. Also, see whether the problem happens in a freshly started Emacs without loading your init file (start Emacs with the -q switch to prevent loading the init file). If the problem does not occur then, it is essential that we know the contents of any programs that you must load into the Lisp world in order to cause the problem to occur.

If the problem does depend on an init file or other Lisp programs that are not part of the standard Emacs system, then you should make sure it is not a bug in those programs by complaining to their maintainers first. After they verify that they are using Emacs in a way that is supposed to work, they should report the bug.

If you can tell us a way to cause the problem without visiting any files, please do so. This makes it much easier to debug. If you do need files, make sure you arrange for us to see their exact contents. For example, it can often matter whether there are spaces at the ends of lines, or a newline after the last line in the buffer (nothing ought to care whether the last line is terminated, but tell that to the bugs).

The easy way to record the input to Emacs precisely is to write a dribble file; execute the Lisp expression:

 
(open-dribble-file "~/dribble")

using Meta-ESC or from the `*scratch*' buffer just after starting Emacs. From then on, all Emacs input will be written in the specified dribble file until the Emacs process is killed.

For possible display bugs, it is important to report the terminal type (the value of environment variable TERM), the complete termcap entry for the terminal from `/etc/termcap' (since that file is not identical on all machines), and the output that Emacs actually sent to the terminal. The way to collect this output is to execute the Lisp expression:

 
(open-termscript "~/termscript")

using Meta-ESC or from the `*scratch*' buffer just after starting Emacs. From then on, all output from Emacs to the terminal will be written in the specified termscript file as well, until the Emacs process is killed. If the problem happens when Emacs starts up, put this expression into your init file so that the termscript file will be open when Emacs displays the screen for the first time. See section 27.7 The Init File. Be warned: it is often difficult, and sometimes impossible, to fix a terminal-dependent bug without access to a terminal of the type that stimulates the bug.

The newsgroup `comp.emacs.xemacs' may be used for bug reports, other discussions and requests for assistance.

If you don't have access to this newsgroup, you can subscribe to the mailing list version: the newsgroup is bidirectionally gatewayed into the mailing list `xemacs@xemacs.org'.

To be added or removed from this mailing list, send mail to `xemacs-request@xemacs.org'. Do not send requests for addition to the mailing list itself.

The mailing lists and newsgroups are archived on our anonymous FTP server, `ftp.xemacs.org', and at various other archive sites around the net. You should also check the `FAQ' in `/pub/xemacs' on our anonymous FTP server. It provides some introductory information and help for initial configuration problems.


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