GNU Emacs FAQ (4/5, 125-151): Keybindings/Output

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#2043

From: Steven Byrnes
Date: Tue, 04 May 1993 02:52

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Archive-Name: GNU-Emacs-FAQ/part4
Last-Modified: Sat, 6 Mar 1993 21:13:32 GMT
Last-Posted: Tue, 4 May 1993 02:52:18 GMT

GNU Emacs FAQ: Keybindings/Output

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Changing Key Bindings and Handling Key Binding Problems

125: How do I bind keys (including function keys) to commands?

1. Find out what character sequence is generated by the keystroke sequence
you wish to bind to a command. See question 129 for how to do this.
Keep in mind that the character sequences generated by a keystroke
sequence varies from one terminal to another. You may also get
different results depending on what type of machine you are running on
(see question 128). For example, these keystrokes may generate these
character sequences:

F1 ---> ESC [ 2 2 4 z
Shift-R10 ---> ESC O t
L7 ---> ESC [ 3 1 ~
Remove ---> C-@

2. Figure out what the Emacs Lisp syntax is for this character sequence.
Inside an Emacs Lisp string, RET, LFD, DEL, ESC, SPC, and TAB are
specified with `\r', `\n', `\C-?', `\e', ` ', and `\t'. C-x is
specified by `\C-x'. M-x is specified the same was as "ESC x".
(Control characters may also be specified as themselves, but I don't
recommend it.) An Emacs Lisp string begins and ends with the double
quote character, `"'. Here are some examples:

ESC [ D ---> "\e[D"
ESC [ 2 2 7 z ---> "\e[227z"
ESC [ 1 8 ~ ---> "\e[18~"
C-M-r ---> "\e\C-r"

3. If some prefix of the character sequence is already bound, you must
unbind it by binding it to `nil'. For example:

(global-set-key "\e[" nil)

4. Pick a command to bind your key sequence to. A command can be a
"symbol" with a function definition, or a "lambda list", or a string
(which is treated as a macro). For example:

(global-set-key "\e[D" 'backward-char)
(global-set-key "\e[227~" "\exgoto-line\r") ; macro

See `Key Bindings' and `Rebinding' in the online manual.

In Emacs 19 (including Lucid Emacs), you can bind function key F24 like
this:

(global-set-key 'f24 'some-command)

126: Why does Emacs say `Key sequence XXX uses invalid prefix characters'?

A prefix of the character sequence you were trying to bind was already
bound. Usually, the sequence is "ESC [", in which case you should
evaluate this form first:

(define-key esc-map "[" nil)

NOTE: By default, "ESC [" is bound to backward-paragraph, and if you do
this you will lose this key binding. For most people, this is not a
problem.

See question 125.

127: Why doesn't this [terminal or window-system setup] code work in my
.emacs file, but it works just fine after Emacs starts up?

This is because you're trying to do something in your .emacs file that
needs to be postponed until after the terminal/window-system setup code
is loaded. This is a result of the order in which things are done
during the startup of Emacs. For more details see question 135.

In order to postpone the execution of Emacs Lisp code until after the
terminal/window-system setup, set the value of the variable
term-setup-hook or window-setup-hook to be a function which does what
you want.

See etc/OPTIONS for a complete explanation of what Emacs does every time
it is started.

Here is a simple example of how to set term-setup-hook:

(setq term-setup-hook
(function
(lambda ()
(cond ((string-match "\\`vt220" (or (getenv "TERM") ""))
;; Make vt220's "Do" key behave like M-x:
(define-key CSI-map "29~" 'execute-extended-command))
))))

128: How do I use function keys under X Windows?

This depends on whether you are running Emacs inside a terminal emulator
window, or whether you are allowing Emacs to create its own X window.
You can tell which you are doing by noticing whether Emacs creates a new
window when you start it.

If you are running Emacs inside a terminal emulator window, then it
behaves exactly as it does on any other tty. In this case, for function
keys to be useful, they must generate character sequences that are sent
to the programs running inside the window as input. The `xterm' program
has two different sets of character sequences that it generates when
function keys are pressed, depending on the sunFunctionKeys X resource
and the -sf and +sf command line options. (To find out what these key
sequences are, see question 129.) In addition, with xterm,
you can override what key sequence a specific function key (or any other
key) will generate with the `translations' resource. This, for example:

XTerm.VT100.Translations: #override \
<KeyPress>F1: string(0x1b) string("[xyzzy")

makes the function key F1 generate the character sequence "ESC [xyzzy".

On the other hand, if Emacs is managing its own X window, the following
description applies. Emacs receives `KeyPress' events from the X server
when a key is pressed while the keyboard focus is in its window. The
KeyPress event contains an X "keysym" code, which is simply an arbitrary
number corresponding to the name of the keysym, and information on which
"modifiers" such as `control' and `shift' are active. For example, the
`Tab' keysym is 0xff09. (Generally, a key on the keyboard will generate a
keysym whose name is the same as the label on the key, ie. the `Tab' key
will normally generate the `Tab' keysym. This can be changed with the
xmodmap program.) Emacs recognizes all the keysyms that correspond to
standard ASCII characters and internally uses the ASCII character instead.

(WARNING: I am about to describe a gross, disgusting hack to you, have
your barf bag ready.)

When Emacs receives the X keysym of one of the arrow keys, it behaves
the same as if it had received a letter key with the control modifier
down as follows (this is hard-coded):

Up becomes C-p
Down becomes C-n
Right becomes C-f
Left becomes C-b

The way Emacs treats other keysyms depends on what kind of machine it was
compiled on. The type of the display machine is irrelevant! Function
keys are mapped internally to escape sequences, while other keys are
completely ignored.

1. If compiled on a Sun, Emacs recognizes these X keysyms that
are normally on a Sun keyboard:

F1 through F9
L1 through L10 (same as F11 through F20)
R1 through R15 (same as F21 through F35)
(The keys labelled R8, R10, R12, and R14 usually are mapped to the
X keysyms Up, Left, Right, and Down.)
Break (the `Alternate' key is given this keysym)

These keys work like Sun function keys. When Emacs recieves the
keysym, it will internally use character sequences that look like "ESC
[ ### z", where ### is replaced by a number. The character sequences
are identical to those generated by Sun's keyboard under SunView. Any
function key not listed above generates "ESC [ - 1 z".

In order to use these key sequences, they should be bound to commands
using the standard key binding methods, just as if Emacs were running
on a regular terminal.

WARNING: F11 and L1 are the same keysym in X, as are F12 and L2, etc.
{Yes, this is stupid. Complain to the X consortium.}

2. If not compiled on a Sun, the function keys will appear to Emacs in a
way remarkably similar to the keys of a DEC LK201 keyboard (used on
some VT series terminals). These X keysyms will be recognized:

F1 through F20
Help (treated same as F15)
Menu (treated same as F16, is the LK201 `Do' key)
Find
Insert (LK201 `Insert Here' key)
Select
Prior (LK201 `Prev Screen' key *** ONLY IN 18.58 AND LATER ***)
Next (LK201 `Next Screen' key *** ONLY IN 18.58 AND LATER ***)

And finally, the LK201 key labelled `Remove' (or `Delete') is often
mapped to the Delete keysym which generates the DEL character (C-?)
instead of the key sequence given by the LK201 `Remove' key. It may
also be mapped to some other keysym, such as `_Remove', in which case
you can't use it from within Emacs at all.

Each function key will be internally converted to a character sequence
that looks like "ESC [ ## ~", where ## is replaced by a number. The
character sequences are identical to those generated by a LK201
keyboard. Any function key not listed above generates "ESC [ - 1 ~".

For the complete list of the numbers which are generated by the function
keys, look in the file src/x11term.c at the definitions of the function
stringFuncVal.

If you are running Emacs on a Sun machine, even if your X display is
running on a non-Sun machine (eg., an X terminal), you get the setup
described above for Suns. The determining factor is what type of
machine Emacs is running (was compiled) on, not what type of machine
your X display is on.

If you have function keys not listed above on your keyboard, you can use
`xmodmap' to change their keysym assignments to get keys that Emacs will
recognize, but that may screw up other programs.

X resources are not used by Emacs to affect the key sequences generated.
In particular, there are no X key "translations" for Emacs.

If you have function keys not listed above and you don't want to use
xmodmap to change their names, you might want to make a modification to
your Emacs. Johan Vromans <jv@mh.nl> has made available a patch for Emacs
that adds the x-rebind-key function of Epoch to Emacs 18.58. This allows
another layer of key rebinding before Emacs even sees the keys, and in
this layer you can rebind all of the keys and modifier combinations as
well.

Anonymous FTP:
/ftp.eu.net:gnu/emacs/FP-Xfun.Z
/ftp.urc.tue.nl:pub/tex/emacs/FP-Xfun

Johan Vromans explains what this buys for you:

After implementing this, all keyboard keys can be configured to send
user definable sequences, eg.,

(x-rebind-key "KP_F1" 0 "\033OP")

This will have the keypad key PF1 send the sequence "ESC O P", just like
an ordinary VT series terminal.

129: How do I tell what characters my function or arrow keys emit?

Use this function by Randal L. Schwartz <merlyn@iwarp.intel.com>:

(defun see-chars ()
"Displays characters typed, terminated by a 3-second timeout."
(interactive)
(let ((chars "")
(inhibit-quit t))
(message "Enter characters, terminated by 3-second timeout.")
(while (not (sit-for 3))
(setq chars (concat chars (list (read-char)))
quit-flag nil)) ; quit-flag maybe set by C-g
(message "Characters entered: %s" (key-description chars))))

Alternatively, use the "C-h l" view-lossage command, which will display
the last 100 characters Emacs has seen in its input stream. Kevin
Gallagher <kgallagh@digi.lonestar.org> suggests typing some unique string
like "wxyz", typing the key in question, then typing "C-h l". The
characters that appear between "wxyz" and "C-h l" were generated by the
key.

130: How do I set the X key "translations" for Emacs?

Sorry, you can't; there are no "translations" to be set. Emacs is not
written using the Xt library. The only way to affect the behavior of keys
within Emacs is through `xmodmap' (outside Emacs) or `define-key' (inside
Emacs).

131: How do I handle C-s and C-q being used for flow control?

C-s and C-q are used in the XON/XOFF flow control protocol. This screws
up Emacs because it binds these characters to commands. Also, by default
Emacs will not honor them as flow control characters and may overwhelm
output buffers. Sometimes, intermediate software using XON/XOFF flow
control will prevent Emacs from ever seeing C-s and C-q.

Possible solutions:

* Disable the use of C-s and C-q for flow control.

You need to determine what is the cause of the flow control.

* your terminal

Your terminal may use XON/XOFF flow control to have time to display
all the characters it receives. For example, VT series terminals do
this. It may be possible to turn this off from a setup menu. For
example, on a VT220 you may select `No XOFF' in the setup menu. This
is also true for some terminal emulation programs on PCs.

When you turn off flow control at the terminal, you will also need to
turn it off at the other end, which might be at the computer you are
logged in to or at some terminal server in between.

If you turn off flow control, characters may be lost; using a printer
connected to the terminal may fail. You may be able to get around
this problem by modifying the `termcap' entry for your terminal to
include extra NUL padding characters.

* a modem

If you are using a dialup connection, the modems may be using XON/XOFF
flow control. I don't know how to get around this.

* a router or terminal server

Some network box between the terminal and your computer may be using
XON/XOFF flow control. It may be possible to make it use some other
kind of flow control. You will probably have to ask your local
network experts for help with this.

* tty and/or pty devices

If your connection to Emacs goes through multiple tty and/or pty
devices, they may be using XON/XOFF flow control even when it is not
necessary.

Eirik Fuller <eirik@theory.tn.cornell.edu> writes:

Some versions of `rlogin' (and possibly telnet) do not pass flow
control characters to the remote system to which they connect. On
such systems, Emacs on the remote system cannot disable flow control
on the local system. Sometimes `rlogin -8' will avoid this problem.

One way to cure this is to disable flow control on the local host
(the one running rlogin, not the one running rlogind) using the stty
command, before starting the rlogin process. On many systems, `stty
start u stop u' will do this.

Some versions of `tcsh' will prevent even this from working. One
way around this is to start another shell before starting rlogin,
and issue the stty command to disable flow control from that shell.

Use `stty -ixon' instead of `stty start u stop u' on some systems.

* Make Emacs speak the XON/XOFF flow control protocol.

You can make Emacs treat C-s and C-q as flow control characters by
evaluating this form:

(set-input-mode nil t)

If you are fixing this for yourself, simply put the form in your .emacs
file. If you are fixing this for your entire site, the best place to
put it is unclear. I don't know if this has any effect when used in
lisp/site-init.el when building Emacs; I've never tried that. {Can
someone tell me whether it works?} Putting things in users' .emacs files
has a number of problems.

Putting this form in lisp/default.el has the problem that if the user's
.emacs file has an error, this will prevent lisp/default.el from being
loaded and Emacs may be unusable for the user, even for correcting their
.emacs file (unless they're smart enough to move it to another name). A
possible solution is to initially disable C-s and C-q by setting
keyboard-translate-table in lisp/site-init.el, either with swap-keys
(see question 136) or with the following form:

;; by Roger Crew <crew@cs.stanford.edu>:
(setq keyboard-translate-table
"\C-@\C-a\C-b\C-c\C-d\C-e\C-f\C-g\C-h\C-i\C-j\C-k\C-l\C-m\C-n\C-o\C-p\C-^\C-r\C-\\\C-t\C-u\C-v\C-w\C-x\C-y\C-z\C-[\C-s\C-]\C-q\C-_")

This will at least prevent Emacs from being confused by the flow control
characters, even if lisp/default.el cannot be loaded. Then, in
lisp/default.el, enable XON/XOFF flow control with set-input-mode.

For further discussion of this issue, read the file PROBLEMS in the
Emacs distribution.

132: How do I use commands bound to C-s and C-q (or any key) if these keys
are filtered out?

I suggest swapping C-s with C-\ and C-q with C-^:

(swap-keys ?\C-s ?\C-\\)
(swap-keys ?\C-q ?\C-^)

See question 136 for the implementation of swap-keys. This method
has the advantage that it simultaneously swaps the characters everywhere
throughout Emacs, while just switching the keybindings will miss important
places where the character codes are stored (eg., the search-repeat-char
variable, major mode keymaps, etc.).

To do this for an entire site, you may want to swap the keys in
lisp/default.el. If only some of your users are connecting through
XON/XOFF flow-controlled connections, you will want to do this
conditionally. I suggest pre-swapping them in lisp/site-init.el when
Emacs is built, and then in lisp/default.el, if it is determined to be
safe, they can be reenabled (being careful not to screw up any other key
mappings users might have established using keyboard-translate-table).
See question 131 for an easy way to pre-swap these keys.

WARNING: If you do this for an entire site, the users will be confused by
the disparity between what the documentation says and how Emacs actually
behaves.

133: Why does the `BackSpace' key invoke help?

The BackSpace key (on every keyboard I've used) generates ASCII code 8.
C-h sends the same code. In Emacs by default C-h invokes help-command.
This is intended to be easy to remember since the first letter of "help"
is "h". The easiest solution to this problem is to use C-h (and
BackSpace) for help and DEL (the Delete key) for deleting the previous
character.

For many people this solution may be problematic:

* They normally use BackSpace outside of Emacs for deleting the previous
character typed. This can be solved by making DEL be the command for
deleting the previous character outside of Emacs. This command will do
this on many Unix systems:

stty erase '^?'

* The person may prefer using the BackSpace key for deleting the previous
character because it is more conveniently located on their keyboard or
because they don't even have a separate Delete key. In this case, the
BackSpace key should be made to behave like Delete. There are several
methods.

* Under X Windows, the easiest solution is to change the BackSpace key
into a Delete key like this:

xmodmap -e "keysym BackSpace = Delete"

* Some terminals (eg., VT3## terminals) allow the character generated by
the BackSpace key to be changed from a setup menu.

* You may be able to get a keyboard that is completely programmable.

* Under X or on a dumb terminal, it is possible to swap the BackSpace
and Delete keys inside Emacs:

(swap-keys ?\C-h ?\C-?)

See question 136 for the implementation of swap-keys.

* Another approach is to switch keybindings and put help on "C-x h"
instead:

(global-set-key "\C-h" 'delete-backward-char)
(global-set-key "\C-xh" 'help-command) ; override mark-whole-buffer

Other popular key bindings for help are M-? and "C-x ?".

WARNING: Don't try to bind DEL to help-command, because there are many
modes that have local bindings of DEL that will interfere.

134: Why doesn't Emacs look at the stty settings for Backspace vs. Delete?

Good question!

135: Why don't the arrow keys work?

When Emacs starts up, it doesn't know anything about arrow keys at all
(except when running under X, see question 128). During the process of
starting up, Emacs will load a terminal-specific initialization file for
your terminal type (as determined by the environment variable TERM), if
one exists. This file has the responsibility for enabling the arrow keys.

There are several things that can go wrong:

1. There is no initialization file for your terminal.

You can determine this by looking in the lisp/term directory. If your
terminal type (as determined by the TERM environment variable) is
xxx-yy-z, then the first of these files in the lisp/term directory will
be loaded as the terminal-specific initialization file: xxx-yy-z.el,
xxx-yy.el, or xxx.el.

There are two major cases of this problem:

* Your terminal type is very similar to one that has an init file.

In this case, there are several techniques suggested by Colin Jensen
<cjensen@ampex.com>, Ben Liblit <Liblit@cs.psu.edu>, and Marc
Auslander <marc@watson.ibm.com>:

A. Add a symbolic link in lisp/term for your terminal type that
points to the similar type. For example, you could make VT102
terminals work with this command:

ln -s vt100.el vt102.el

This fixes things for everyone on the system who uses the terminal
type.

B. If you can't do the solution in part A, you can add code to your
term-setup-hook that loads the correct file like this:

(setq term-setup-hook
(function
(lambda ()
(cond ((equal "vt102" (or (getenv "TERM") ""))
(load (concat term-file-prefix "vt100")))
(;; Code for other terminal types goes here ...
)))))

C. If you use `tset' to set your TERM environment variable when you
login, you can use the `-m' switch to tell tset to use a terminal
type known by Emacs instead of another similar one. For example,
specifying this:

tset ... -m 'dec-vt220:vt220' ...

will make tset say you are on a `vt220' instead of a `dec-vt220'.

D. Interactively, you can type "M-x load-library RET term/vt100" to
load the terminal-specific initialization files for VT100
terminals.

* Your terminal type is not similar to one that has an init file.

One can be made for your terminal, or you can just add code to your
own .emacs to handle this problem for yourself. For example, if your
terminal's arrow keys send these character sequences:

Up: ESC [ A
Down: ESC [ B
Right: ESC [ C
Left: ESC [ D

then you can bind these keys to the appropriate commands with code in
your .emacs like this:

(setq term-setup-hook
(function
(lambda ()
(cond ((string-match "\\`xyzzy" (or (getenv "TERM") ""))
;; First, must unmap the binding for left bracket
(or (keymapp (lookup-key global-map "\e\["))
(define-key global-map "\e\[" nil))
;; Enable terminal type xyzzy's arrow keys:
(define-key global-map "\e\[A" 'previous-line)
(define-key global-map "\e\[B" 'next-line)
(define-key global-map "\e\[C" 'forward-char)
(define-key global-map "\e\[D" 'backward-char))
((string-match "\\`abcde" (or (getenv "TERM") ""))
;; Do something different for terminal type abcde
;; .....
)))))

NOTE: You may have to restart Emacs to get changes to take effect.

NOTE: Your arrow keys may send sequences beginning with "ESC O" when
Emacs is running, even if they send sequences beginning with "ESC [" at
all other times. This is because Emacs uses any command there may be
in your terminal's termcap entry for putting the terminal into
"Application Keypad Mode". Just map these sequences the same way as
above.

The next two cases are problems even if there is a initialization file for
your terminal type.

2. The initialization file for your terminal doesn't bind arrow keys.

If your terminal type is `xterm', you will have to bind the arrow keys
as in part 1 above, since the xterm.el file doesn't do anything useful.
There may be other terminal types with the same problem.

3. Your terminal's arrow keys send individual control characters.

For example, the arrow keys on an ADM-3 send C-h, C-j, C-k, and C-l.

There is not much Emacs can do in this situation, since all the control
characters except for C-^ and C-\ are already used as Emacs commands.
It may be possible to convince the terminal to send something else when
you press the arrow keys; it is worth investigating.

You have to make the hard choices of how to rebind keys to commands to
make things work the way you want. Another alternative is to start
learning the standard Emacs keybindings for moving point around: C-b,
C-f, C-p, and C-n. Personally, I no longer use the arrow keys when
editing because I have switched keyboards so many times.

4. Your terminal's arrow keys send sequences beginning with "ESC [".

Due to an extremely poor design decision (ie., these sequences are ANSI
standard), none of the the terminal-specific initialization files that
are distributed with Emacs will bind these character sequences to the
appropriate commands by default. (This also applies to any other
function keys which generate character sequences starting with "ESC
[".) This is because it was deemed far more important to preserve the
binding of M-[ to the backward-paragraph command. It appears that this
will change in Emacs 19.

Some of the terminal-specific initialization files that come with Emacs
provide a command enable-arrow-keys that will fix this problem. To get
this automatically invoked, put this in your .emacs:

(setq term-setup-hook
(function
(lambda ()
(if (fboundp 'enable-arrow-keys) (enable-arrow-keys)))))

We put this in our lisp/default.el file, so users don't have to worry
about it:

;; don't override a user's term-setup-hook
(or term-setup-hook
(setq term-setup-hook
(function
(lambda ()
(and (fboundp 'enable-arrow-keys)
;; don't override a user key mapping
(eq 'backward-paragraph (lookup-key esc-map "["))
(enable-arrow-keys))))))

If your terminal type is `sun', you should put this in your .emacs
instead (or in addition to the above):

(setq sun-esc-bracket t)

It is possible that the terminal-specific initialization file for your
terminal type was written locally and does not follow the rule
mentioned above. In this case you may need to inspect it to find out
how to enable the arrow keys. (Actually, if it was written locally, it
probably enables the arrow keys by default.)

136: How do I "swap" two keys?

When Emacs receives a character, you can make Emacs behave as though it
received another character by setting the value of
keyboard-translate-table. The following Emacs Lisp will do this for you,
allowing you to "swap" keys. After arranging for this Lisp to be
evaluated by Emacs, you can evaluate `(swap-keys ?A ?B)' to swap A and B.

(defun swap-keys (key1 key2)
"Swap keys KEY1 and KEY2 using map-key."
(map-key key1 key2)
(map-key key2 key1))

(defun map-key (from to)
"Make key FROM behave as though key TO was typed instead."
(setq keyboard-translate-table
(concat keyboard-translate-table
(let* ((i (length keyboard-translate-table))
(j from)
(k i)
(str (make-string (max 0 (- j (1- i))) ?X)))
(while (<= k j)
(aset str (- k i) k)
(setq k (1+ k)))
str)))
(aset keyboard-translate-table from to)
(let ((i (1- (length keyboard-translate-table))))
(while (and (>= i 0) (eq (aref keyboard-translate-table i) i))
(setq i (1- i)))
(setq keyboard-translate-table
(if (eq i -1)
nil
(substring keyboard-translate-table 0 (1+ i))))))

NOTE: You must evaluate the definition of these functions before calling
them! For example, list the function definitions before their use in your
.emacs file.

NOTE: These functions take two numbers as arguments. The example above,
`(swap-keys ?A ?B)' is actually `(swap-keys 65 66)', because `?A' is
merely notation for 65, the ASCII value of `A'.

NOTE: These functions only work for single characters. You cannot swap
two multi-character sequences.

137: How do I produce C-XXX with my keyboard?

For C-@ and C-^, often you can just type Control-2 and Control-6. For
C-_, you may have to hold down the shift key, typing Control-Shift-Hyphen.
C-@ can often be generated by typing Control-Space. C-@ is often called
the NUL character, and has ASCII value 0. C-_ can often be generated by
typing Control-7 or Control-/. C-? (aka DEL) may be generated by typing
Shift-BackSpace or Control-BackSpace or a key labelled Delete or Del.

Try Control with all of the digits on your keyboard to see what gets
generated.

138: What if I don't have a Meta key?

Instead of typing M-a, you can type "ESC a" instead. In fact, Emacs
converts M-a internally into "ESC a" anyway (depending on the value of
meta-prefix-char).

139: What if I don't have an Escape key?

Type C-[ instead. This should send ASCII code 27 just like an Escape
key would. Try also C-;.

140: How do I type DEL on PC terminal emulators?

Some IBM PC compatibles do not have a key labeled `Del' or `Delete' {is
this true?}. Those that do generally have it in an inconvenient location.
(Also, in some terminal emulators, the `Del' key does not transmit DEL.)
The result is the standard "BackSpace invoking help" problem (see question
133).

The usual solution, suggested by Michael Covington
<mcovingt@aisun1.ai.uga.edu>, is to somehow tell the terminal emulator
program that BackSpace should transmit DEL. Read the program's manual.
Shift-BackSpace or Control-BackSpace may send DEL. The `Del' key may only
send DEL if the NumLock key hasn't been pressed.

141: Can I make my `Compose Character' key behave like a Meta key?

On a dumb terminal such as a VT220, no. It is rumored that certain VT220
clones could have their Compose key configured this way. If you're using
X, you might be able to do this with the `xmodmap' program (this is
what I do).

142: How do I bind a combination of modifier key and function key?

Unless you're using Emacs under emacstool (or xvetool?), have a working
version of x-rebind-key (see question 128), or are using Emacs 19 (Lucid
Emacs), you can't do this with Emacs alone.

If you are using emacstool, Emacs sees different character sequences for
the combination of a modifier and a function key from what it sees for the
function key alone. See etc/emacstool.1 for more information. Since
Emacs sees different character sequences, you can bind these different
sequences to different commands.

If you are running Emacs inside a terminal emulator window like xterm, you
can modify its translation tables to make it generate different character
sequences for the combination of a modifier and a function key. For
example, this X resource setting:

XTerm.VT100.Translations: #override \
Shift<KeyPress>F1: string(0x1b) string("[xyzzy")

makes Shift-F1 generate the character sequence "ESC [ xyzzy". You can
bind these character sequences in Emacs as normal. Nick Ruprecht
<ruprecht@informatik.uni-freiburg.de> has written an extensive X
translation mapping for xterm that does this. {Does this have an FTP
site?}

If you have x-rebind-key, you can have any arbitrary combination of
modifiers with a key replaced by any sequence of "normal" characters. For
example, this makes Shift-Return behave as though you had typed "C-x C-e"
(example from Jerry Graves):

(x-rebind-key "Return" 'shift "\C-x\C-e")

In Emacs 19 (Lucid Emacs), you can bind Meta-Left-Arrow like this (example
from Jamie Zawinski):

(global-set-key '(meta left) 'backward-word)

With the last two methods, use `xmodmap' and `xev' to discover the keysym
and modifier names.

143: Why doesn't my Meta key work in an xterm window?

Try all of these methods before asking for further help:

* You may have big problems using `mwm' as your window manager. {Does
anyone know a good generic solution to allow the use of the Meta key in
Emacs with mwm?}

* For X11R4: Make sure it really is a Meta key. Use `xev' to find out
what keysym your Meta key generates. It should be either Meta_L or
Meta_R. If it isn't, use xmodmap to fix the situation.

* Make sure the pty the xterm is using is passing 8 bit characters.
`stty -a' (or `stty everything') should show `cs8' somewhere. If it
shows `cs7' instead, use `stty cs8 -istrip' (or `stty pass8') to fix
it.

* If there is an rlogin connection between the xterm and the Emacs, the
`-8' argument may need to be given to rlogin to make it pass all 8
bits of every character.

* If the Emacs is running under Ultrix, it is reported that evaluating
(set-input-mode t nil) helps.

* If all else fails, you can make xterm generate "ESC W" when you type
M-W, which is the same conversion Emacs would make if it got the M-W
anyway. In X11R4, the following resource specification will do this:

XTerm.VT100.EightBitInput: false

(This changes the behavior of the insert-eight-bit action.)

With older xterms, you can specify this behavior with a translation:

XTerm.VT100.Translations: #override \
Meta<KeyPress>: string(0x1b) insert()

You might have to replace `Meta' with `Alt'.

144: Why doesn't my ExtendChar key work as a Meta key under HP-UX 8.0?

This is a result of an internationalization extension in X11R4 and the
fact that HP is now using this extension. Emacs assumes that
XLookupString returns the same result regardless of the Meta key state
which is no longer necessarily true. Until Emacs is fixed, the temporary
kludge is to run this command after each time the X server is started but
preferably before any xterm clients are:

xmodmap -e 'remove mod1 = Mode_switch'

NOTE: This will disable the use of the extra keysyms systemwide, which
may be undesirable if you actually intend to use them.

145: Where can I get key bindings to make Emacs emulate WordStar?

There is a package `wordstar' by Jim Frost <jimf@saber.com> and
`ws-mode.el' by Juergen Nickelsen <nickel@cs.tu-berlin.de>. Check in the
Emacs Lisp Archive (see question 89).

146: Where can I get an XEDIT emulator for Emacs?

This question comes up once every couple of months. I have never seen a
positive reply, so I presume no one has ever written one.

Using Emacs with Alternate Character Sets

147: How do I make Emacs display 8-bit characters?

There is a patch called the `8-bit ctl-arrow patch' that allows Emacs to
display characters with codes from 128 to 255. {The original appears to
have been by Kenneth Cline <cline@proof.ergo.cs.cmu.edu>.} Partially based
on Johan Widen's earlier work, Johan Vromans <jv@mh.nl> has updated this
patch for Emacs 18.58 along with some other 8-bit improvements.

Anonymous FTP:
/ftp.eu.net:gnu/emacs/FP-EightBit.Z
/ftp.urc.tue.nl:/pub/tex/emacs/FP-EightBit
/cs.purdue.edu:pub/ygz/cemacs.tar.Z:cemacs/8bit-patch-18.57
/sics.se:archive/emacs-18.55-8bit-diff
/laas.laas.fr:pub/emacs/patch-8bit-18.55
/laas.laas.fr:pub/emacs/patch-8bit-18.57

Via e-mail:
To: mail-server@sics.se
body: send emacs-18.55-8bit-diff

Anders Edenbrandt <anderse@dna.lth.se> has produced a more comprehensive
patch for Emacs 18.59 that allows for 8-bit input and output.

Anonymous FTP:
/ftp.efd.lth.se:pub/gnu/emacs_8-bit.patch

In the words of the author:

With these patches, Emacs becomes fully 8-bit operational. There is
support for displaying 8-bit characters, as well as for entering such
characters from the keyboard. In addition, upcase/lowcase tranlatsion
is supported, accented characters are recognized as "letters" (important
when doing 'forward-word', for example), and text with 8-bit characters
can be sorted correctly.

A Meta-shift key can still be used, provided that you run in an
environment where it is possible to distinguish between a character
entered using the Meta-shift key and one entered directly. The diffs
include patches to make this work under SunView (with emacstool) as
well as under X. If you can't use a Meta-shift key, you have to enter
Meta-commands with the ESC-prefix.

The most comprehensive patches for 8-bit output are by Howard Gayle
(originally for Emacs 18.55. These patches allow displaying any arbitrary
string for a given 8-bit character (except TAB and C-j). Also supported
is defining the sorting order and the uppercase and lowercase
translations. It is reported that the 8-bit character support in Emacs 19
is largely based on these patches. Thomas Bellman
<Bellman@lysator.liu.se> has updated these patches for Emacs 18.59.

Anonymous FTP:
/sics.se:archive/emacs-gayle.tar.Z (patches for 18.55)
/ftp.lysator.liu.se:pub/emacs/gayle-18.58.diff.tar.Z (patches)
/ftp.lysator.liu.se:pub/emacs/emacs-18.59-gayle.tar.Z (patched Emacs)

Epoch's 8-bit character support is based on Anders Edenbrandt's patches.
Lucid Emacs has the ctl-arrow patch installed. Nemacs displays 8-bit
characters, and it may be useful for displaying the 8-bit ISO-8859
alphabet, but I don't know for sure (see question 149).

148: How do I input 8-bit characters?

Minor modes for ISO Latin-1 that allow one to easily input this character
set have been written by several people. Such modes have been written by
Matthieu Herrb <matthieu@laas.fr> (laas.laas.fr:pub/emacs/iso-latin-1.el),
Johan Vromans <jv@mh.nl> {FTP site??}, and Marc Shapiro
<shapiro@sor.inria.fr> {FTP site??}.

These approaches differ from the one taken by Anders Edenbrandt in that
his method uses direct 8-bit input, while these methods use a compose
sequence for 8-bit characters. {I have heard conflicting reports on
whether this results in losing the Meta key. Perhaps this depends on
whether Emacs is running under X. Can someone resolve this?}

Karl Heuer <karl@haddock.ima.isc.com> is said to have a patch to allow
8-bit input. Georg-Wilhelm Koltermann <gwk@crmunich0.cray.com> also has a
patch for either 18.57 or 18.58 that allows 8-bit input.

Epoch comes with a patch that allows it to input 8-bit characters, but it
is not enabled by default. {Is this right?}

Jamie Zawinski says:

Lucid GNU Emacs allows the input of any ISO-8859/1 keysyms that your
keyboard generates (see xmodmap), and contains a package that implements
a DEC/OpenWindows-like "Compose" key for systems which don't have one.

149: Where can I get an Emacs that can handle kanji characters?

Nemacs 3.3.2 (Nihongo GNU Emacs) is a modified version of GNU Emacs 18.55
that handles kanji characters. It is available via anonymous FTP:

/crl.nmsu.edu:pub/misc/nemacs-3.3.2.tar.Z
/miki.cs.titech.ac.jp:JAPAN/nemacs/nemacs-3.3.2.tar.Z

You might also need files for "wnn", a kanji input method
(wnn-4.0.3{-README,.tar.Z} {on which machine?}). You need a terminal (or
terminal emulator) that can display text encoded in JIS, Shift-JIS, or EUC
(Extended Unix Code), or the ability to run Nemacs as a direct X Window
client.

150: Where can I get an Emacs that can handle Chinese?

`cemacs' by Stephen G. Simpson <simpson@math.psu.edu> is a patch to Emacs
18.57 (the ctl-arrow patch) and some Emacs Lisp code that combined with
Cxterm allows using Chinese characters. It is available via anonymous
FTP:

/crl.nmsu.edu:pub/chinese/cemacs.tar.Z
/cs.purdue.edu:pub/ygz/cemacs.tar.Z

Cxterm is available from the same place:

/cs.purdue.edu:pub/ygz/cxterm-11.5.1.tar.Z

151: Where is an Emacs that can handle Semitic (right-to-left) alphabets?

Joel M. Hoffman <joel@wam.umd.edu> writes:

A couple of years ago a wrote a hebrew.el file that allows right-to-left
editing of Hebrew. I relied on the hardware to display the Hebrew
letters, given the right codes, but not for any right-to-left support;
the hardware also doesn't have to send any specific char. codes. Emacs
keeps track of when the user is typing Hebrew vs. English. (The VT-*
terminals in Israel contain built-in support for Hebrew.)

To get it to work I had to modify only a few lines of GNU Emacs's source
code --- just enough to make it 8-bit clean.

[and in a separate message:]

It doesn't produce time-order ["sefer" format] (I wouldn't recommend
trying that with emacs, because converting time-order to screen-order
with arbitrarily long lines is a bit tricky), but I also concocted a
quick filter to convert screen-order into time-order. I'll be happy to
send you the requisite files if you want them. If you're using it for
anything large, however, you'll want something that works better.

Joel Hoffman has also written a "bi-directional bi-lingual Emacs-like"
editor for MS-DOS named Ibelbe (Itty Bitty Emacs-Like Bidirectional
Editor). Ibelbe is written in Turbo Pascal and comes with source code.
Here is the description:

Ibelbe looks like emacs (it even has a minibuffer and filename
completion), and fully supports both right-to-left and left-to-right
editing. Other than an EGA monitor or better, no special hardware is
required. You will need an EGA Hebrew font to use Ibelbe with Hebrew.

Anonymous FTP:
/israel.nysernet.org:israel/msdos/ibelbe.zip
/israel.nysernet.org:israel/msdos/hebfont.zip

Joseph Friedman <yossi@deshaw.com, yossi@Neon.Stanford.EDU> has written
patches for Emacs 18.55 and 18.58 that provide Semitic language support
under X Windows.

Warren Burstein <warren@itex.jct.ac.il> says he has mapped 7-bit keys by
modifying self-insert-command "for Hebrew input on 7-bit keyboards".

A good suggestion is to query archie for files named with `hebrew'.

----------------------------------------------------------------------
Copyright (C) 1990, 1991, 1992 Joseph Brian Wells
Copyright (C) 1992, 1993 Steven Byrnes

This list of frequently asked questions about GNU Emacs with answers
("FAQ") may be translated into other languages, transformed into other
formats (e.g. Texinfo, Info, WWW, WAIS, etc.), and updated with new
information. The same conditions apply to any derivative of the FAQ as
apply to the FAQ itself. Every copy of the FAQ must include this notice
or an approved translation, information on who is currently maintaining
the FAQ and how to contact them (including their e-mail address), and
information on where the latest version of the FAQ is archived (including
FTP information). The FAQ may be copied and redistributed under these
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From: sbyrnes@rice.edu (Steven Byrnes)
Newsgroups: gnu.emacs.help,comp.emacs,news.answers,comp.answers
Subject: GNU Emacs FAQ (4/5, 125-151): Keybindings/Output
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