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5. Delete and Backspace

• Apr 12, 2013  A different manufacturer's mouse allowed me to set BACKSPACE as one of the custom buttons. The Microsoft Mouse and Keyboard Center allows buttons to be reassigned, and even have key combinations applied.
• For example, if I wanted to press the windows key, I would look at that page for the key. 'cmd' has the description 'A generic command button. On PC platforms, this corresponds to the Super key or Windows key, and on Mac it corresponds to the Command key' which is what I am looking for. Now for the code.
• Sep 21, 2019  Linux generates accented characters using special dead keys; these are keys which are pressed in combination with character keys to generate accented forms of those characters. You can identify which specific dead key was used (if more than one exists) by examining the KeyboardEvent 's associated compositionupdate event's data property.
• Are you a Linux-user and tired of the misbehaviour of your backspace and delete keys? Work through this document to fix it once and for all. Also if you want the keyboard to generate special characters in X. Push the key-combination 'Ctrl-x-r' (push the control-key, the x-key. Release it, push the r-key.

Getting Delete and Backspace to work just right is nontrivial,especially in a mixed environment, where you talk to console,to X, to bash, to emacs, login remotely, etc.You may have to edit several configuration files to tell allof the programs involved precisely what you want.On the one hand, there is the matter of which keys generatewhich codes (and how these codes are remapped by e.g. kermitor emacs), and on the other hand the question of what functionsare bound to what codes.

The dead key does not generate a (complete) character by itself, but modifies the character generated by the key struck immediately after. Thus, a dedicated key is not needed for each possible combination of a diacritic and a letter, but rather only one dead key for each diacritic is needed, in addition to the normal base letter keys.

People often complain `my backspace key does not work', as if thiskey had a built-in function `delete previous character'.Unfortunately, all this key, or any key, does is producing a code,and one only can hope that the kernel tty driver andall application programs can be configured such thatthe backspace key indeed does function as a `delete previous character'key.

Most Unix programs get their tty input via the kernel tty driverin `cooked' mode, and a simple stty command determines theerase character. However, programs like bash and emacsand X do their own input handling, and have to be convincedone-by-one to do the right thing.

5.1 How to tell Unix what character you want to use to delete the last typed character

If the character is erased, but in a funny way, then something iswrong with your tty settings. If echoprt is set, then erased charactersare enclosed between and /.If echoe is not set, then the erase char is echoed(which is reasonable when it is a printing character, like #).Most people will want stty echoe -echoprt. Saying stty sanewill do this and more. Saying stty -a shows your current settings.How come this is not right by default? It is, if you use the rightgetty.

/generate-private-key-and-certificate-signing-request.html. Note that many programs (like bash, emacs etc.) have their ownkeybindings (defined in ~/.inputrc,~/.emacs etc.) and are unaffected by the settingof the erase character.

The standard Unix tty driver does not recognize a cursor, or keys(like the arrow keys) to move the current position, and hence does nothave a command `delete current character' either. But for exampleyou can get bash on the console to recognize the Delete key by putting

into ~/.inputrc.

`Getty used to do the right thing with DEL and BS but is broken now?'

Earlier, the console driver would do BS Space BS(010040010)when it got a DEL (177).Nowadays, DEL's are ignored (as they should be,since the driver emulates a vt100). Get a better getty, i.e.,one that does not output DEL.

`Login behaves differently at the first and second login attempts?'

At the first attempt, you are talking to getty. At the second attempt,you are talking to login, a different program.

5.2 How to tell Linux what code to generate when a key is pressed

On the console, or, more precisely, when not in (MEDIUM)RAW mode, use

and under X useNote that (since XFree86-2.1) X reads the Linux settings of the keymapswhen initialising the X keymap. Although the two systems are not100% compatible, this should mean that in many cases the use ofxmodmap has become superfluous.

For example, suppose that you would like the Backspace keyto send a BackSpace (Ctrl-H, octal 010) and the grey Delete keya DEL (octal 0177). Add the following to /etc/rc.local(or wherever you keep your local boot-time stuff):

Note that this will only change the function of these keyswhen no modifiers are used. (You need to specify a keymaps lineto tell which keymaps should be affected if you want to changebindings on more keymaps.)The Linux kernel default letsCtrl-Backspace generate BackSpace - this is sometimes usefulas emergency escape, when you find you can only generate DELs.

The left Alt key is sometimes called the Meta key, and bydefault the combinations AltL-X are bound to the symbol MetaX.But what character sequence is MetaX?That is determined (per-tty) by the Meta flag, set by the commandsetmetamode. The two choices are: ESC X or X or-ed with 0200.

Many distributions have a loadkeys command somewhere in thebootup sequence. For example, one may have the name of the desiredkeymap in /etc/sysconfig/keyboard and the loadkeyscommand that loads it in /etc/rc.d/init.d/keytable.Or one may have the actual default keymap in /etc/default.keytaband the loadkeys command that loads it in /etc/rc.d/boot.Etc. Instead of adding a local modification to the default, one canof course change the default by editing the default keymap or changingthe name of the keymap to be loaded at boot time. Note that loadkeysitself has default keymap defkeymap.map located somewhere under/usr/lib/kbd or /usr/share/kbd (just like all otherkeymaps) and this may not yet be available in single user boot before/usr has been mounted.

`How do I get a dvorak keyboard?'

The command

will give you a dvorak layout, probably by loadingsomething like /usr/lib/kbd/keymaps/i386/dvorak/dvorak.map.gz.Under X, putin XF86Config.

`Why doesn't the Backspace key generate BackSpace by default?'

(i) Because the VT100 had a Delete key above the Enter key.

(ii) Because Linus decided so.

5.3 How to tell X to interchange Delete and Backspace

Or, if you just want the Backspace key to generate a BackSpace:Or, if you just want the Delete key to generate a Delete:(but usually this is the default binding already).

5.4 How to tell emacs what to do when it receives a Delete or Backspace

Put in your .emacs file lines like

Of course you can bind other commands to other keys in the same way.Note that various major and minor modes redefine keybindings.For example, in incremental search mode one finds the codeThis means that it may be a bad idea to use the above twoglobal-set-key commands. There are too many places wherethere are built-in assumptions about Ctrl-H = help and DEL = delete.That doesn't mean that you have to setup keys so that Backspacegenerates DEL. But if it doesn't then it is easiest to remapthem at the lowest possible level in emacs.

5.5 How to tell emacs to interchange Delete and Backspace

Put in your .emacs file lines

Recent versions of emacs have a function keyboard-translateand one may simplify the above toNote that under X emacs can distinguish between Ctrl-h and theBackspace key (regardless of what codes these produce on the console),and by default emacs will view the Backspace key as DEL(and do deletion things, as bound to that character, rather thanhelp things, bound to Ctrl-H). One can distinguish Backspace and Delete,e.g. by

5.6 How to tell kermit to interchange Delete and Backspace

Put in your .kermrc file the lines

5.7 How to tell xterm to interchange Delete and Backspace

5.8 How to tell xterm about your favourite tty modes

Normally xterm will inherit the tty modes from its invoker.Under xdm, the default erase and kill characters are # and @,as in good old Unix Version 6.If you don't like that, you might put something like

in /usr/lib/X11/app-defaults/XTerm or in$HOME/.Xresources, assuming that you have a linein your $HOME/.xinitrc or $HOME/.xsession.

5.9 How to tell non-Motif X applications that the Del key deletes forward

Put

into .Xresources to make non-Motif X applications such as

What Key Combination Generates A Backspace Character Quizlet 4

xfig, xedit, etc., work correctly. (Daniel T. Cobra)

5.10 How to tell xmosaic that the Backspace key generates a DEL

Putting

in your $HOME/.Xdefaults or$HOME/.Xresources helps.(What file? The file that is fed to xrdb, for examplein .xinitrc.)

The netscape FAQ, however, says:

5.11 A better solution for Motif-using programs, like netscape

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Ted Kandell (ted@tcg.net) suggests the following:

Somewhere in your .profile add the following:

If you are using bash, add the following lines to your .inputrc:Add the following lines to your .xinitrc file:

This will definitely work for a PC 101 or 102 key keyboardwith any Linux/XFree86 layout.

The important part to making Motif apps like Netscape work properlyis adding osfBackSpace to keycode 22 in addition to BackSpace.

Note that there must be spaces on either side of the = sign.

5.12 What about termcap and terminfo?

When people have problems with backspace, they tend to look at their termcap(or terminfo) entry for the terminal, and indeed, there does exist a kb(or kbs) capability describing the code generated by the Backspace key.However, not many programs use it, so unless you are having problems with oneparticular program only, probably the fault is elsewhere.Of course it is a good idea anyway to correct your termcap (terminfo) entry.See also below under 'The TERM variable'.

5.13 A complete solution

There are many possibilities to get a functioning system.Can't you give one complete set of settings that works?

One way of getting a setup that works in all contextsis to have the Backspace key generate DEL when on theconsole (or xterm), and BackSpace when under X.Maybe that is most convenient - there are too many X utilitiesthat expect BackSpace, and emacs on the console or xtermexpects DEL, while emacs under X can distinguish [BackSpace]from Ctrl-H and does the right thing.

What is needed?No loadkeys changes, since the Backspace key already generatesDEL by default. No stty settings, they are OK by default.No X settings, they are OK by default.One just has to tell xterm that the Backspace key should generate DEL:put

in .Xresources

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, andin .xinitrc, and you are settled.

For a much more extensive discussion of these things, andalternative solutions, seeAnne Baretta's page.

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A dead key is a special kind of a modifier key on a mechanical typewriter, or computer keyboard, that is typically used to attach a specific diacritic to a base letter.^[1] The dead key does not generate a (complete) character by itself, but modifies the character generated by the key struck immediately after. Thus, a dedicated key is not needed for each possible combination of a diacritic and a letter, but rather only one dead key for each diacritic is needed, in addition to the normal base letter keys.

For example, if a keyboard has a dead key for the grave accent (`), the French character à can be generated by first pressing ` and then a, whereas è can be generated by first pressing ` and then e.^[2]Another example is the Spanish letter Ñ, which can be generated via ~ and N, hence Ñ.

Usually, the diacritic itself can be generated as an isolated character by pressing the dead key followed by space; so a plain grave accent can be typed by pressing ` and then Space.

Usage[edit]

A dead key is different from a typical modifier key (such as AltGr or ⌥ Option) in that rather than being pressed and held while another key is struck, the dead key is pressed and released before striking the key to be modified. In some computer systems, there is no indication to the user that a dead key has been struck so the key appears dead, but in some text-entry systems, the diacritic is displayed, along with an indication that the system is waiting for another keystroke to complete the typing sequence.

On a typewriter, the character modifier functionality is accomplished mechanically, by striking the diacritical mark without advancing the carriage (in modern terminology, diacritical mark keys on typewriters are non-spacing). With most mechanical typewriters, the key on the keyboard caused a small bar of metal to rise; the letter desired was on the end of the bar. In addition to striking the paper through the ribbon, causing ink to be deposited on the paper, the bar would prevent the platen-paper carriage assembly from advancing. Thus, the following letter will strike the same spot on the paper. A typewriter is made in such a way that one could place an acute accent (´) on a q, for example.

Computers, however, work differently. The dead key temporarily changes the mapping of the keyboard for the next keystroke, which activates a special keyboard mode rather than actually generating a modifier character. Instead of the normal letter, a precomposed variant, with the appropriate diacritic, is generated. Each combination of a diacritic and a base letter must be specified in the character set and must be supported by the font in use.

There is no precomposed character to combine the acute accent with the letter q, striking ´ and then q is likely to result in ´q, with the accent and letter as separate characters. However, in some systems, the invalid typing sequence may be discarded. (By using the combining characters available in the Unicode character set, it may be possible to generate a combination that more or less looks like a q with an acute accent (q́), but that technique is quite distinct from the dead key functionality. In addition, since a letter like q does not normally take accents, font makers may not include the font attributes necessary for a combining accent to be applied successfully or in an attractive way. It is necessary to test this usage on a font by font basis, since support for accenting in this way varies considerably.)

Chained dead keys[edit]

Unicode encoded over one hundred precomposed characters with two diacritics, for use in Latin script for Vietnamese and a number of other languages. For convenience, they are generated on most keyboards supporting them, by pressing the two corresponding deadkeys in any order, followed by the letter key. Therefore, these dead keys are chained, which means that the second keystroke does not trigger any insertion, the system being still awaiting another key press.

This chained dead key behavior is toggled by the dead key flag, which is the fourth argument of the DEADTRANS function (after the base character code, the diacritic code, and the composed character code). If this flag is set to its default value zero, the composed character is inserted; if it is set to one, the composed character code is handled as another diacritic code like those due to dead key presses, and occurs typically as a second argument in other deadlist entries.

Chaining dead keys allows for compose key emulation by simply using the dead key feature. This may be performed either with proprietary keyboard editing software,^[3] or with driver development kits.^[4]

Dead keys on various keyboard layouts[edit]

A key may function as a dead key by default, and many non-English keyboard layouts in particular have dead keys directly on the keyboard. The basic US keyboard does not have any dead keys, but the US-International keyboard layout, available on Windows and the X Window System, places some dead keys directly on similar-looking punctuation marks. Old computer systems, such as the MSX, often had a special key labeled dead key, which in combination with the Ctrl and Shift keys could be used to add some of the diacritics commonly needed in the Western European languages (´, `, ˆ and ¨) to vowels that were typed subsequently.

In the absence of a default dead key, even a normal printing key can temporarily be altered to function as a dead key by simultaneously holding down another modifier key (typically AltGr or Option). In Microsoft Word (and in most other text-input fields), using the Control key with a key that usually resembles the diacritic (e.g. ^ for a circumflex) acts as a dead key: ^[5]

• Ctrl+' → á, é, í, ó, ú
• Ctrl+` → à, è, ì, ò, ù
• Ctrl+⇧ Shift+: → ä, ë, ï, ö, ü, ÿ
• Ctrl+⇧ Shift+^ → â, ê, î, ô, û
• Ctrl+⇧ Shift+~ → ã, õ, ñ
• Ctrl+, → ç

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On the Macintosh, many keyboard layouts employ dead keys. In the U.S. layout, the following selection of dead keys appears:

• ⌥ Option+e → á, é, í, ó, ú
• ⌥ Option+` → à, è, ì, ò, ù
• ⌥ Option+u → ä, ë, ï, ö, ü, ÿ
• ⌥ Option+i → â, ê, î, ô, û
• ⌥ Option+n → ã, õ, ñ

For example, when ⌥ Option+E are first pressed simultaneously and then followed by A, the result is á. On a Macintosh, pressing one of these Option-key combinations creates the accent and highlights it, then the final character appears when the key for the base character is pressed. However, some diacritically-marked Latin letters less common in the Western European languages, such as ŵ (used in Welsh) or š (used in many Eastern European languages), cannot be typed with the U.S. layout, which predates Unicode and only provides access to characters found in the legacy Mac Roman character set. Access to many more diacritics is provided by the U.S. Extended keyboard layout.

In AmigaOS, dead keys are generated by pressing Alt in combination with F (acute), G (grave), H (circumflex), J (tilde) or K (trema) (e.g., the ALT-F combination followed by the a key generates á and ALT-F followed by e generates é, whereas ALT-G followed by a generates à and ALT-G followed by e generates è).^[6]Sims 4 key generator no survey online.

See also[edit]

References[edit]

1. ^'Dead Key Definition of Dead Key by Merriam-Webster'. Merriam-webster.com. Retrieved 2017-05-01.
2. ^The Unicode Standard, version 8.0.0, ch.05, §12 Strategies for Handling Nonspacing Marks: Keyboard Input https://www.unicode.org/versions/Unicode8.0.0/ch05.pdf#G1076
3. ^'Chained dead keys'. Kbdedit.com. Retrieved 2017-05-01.
4. ^'Download Windows Driver Kit Version 7.1.0 from Official Microsoft Download Center'. Microsoft.com. 2010-02-26. Retrieved 2017-05-01.
5. ^'How do I get letters with accent marks in Microsoft Word?'. www.computerhope.com. Retrieved 21 February 2019.
6. ^Commodore-Amiga, Inc. AMIGA ROM Kernel Reference Manual LIBRARIES. Addison-Wesley. pp. 823–827. ISBN0-201-56774-1.

External links[edit]

What Key Combination Generates A Backspace Character Quizlet 1