Control key
Encyclopedia
Computing
Computing is usually defined as the activity of using and improving computer hardware and software. It is the computer-specific part of information technology...
, a Control key is a modifier key
Modifier key
In computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....
which, when pressed in conjunction with another key, will perform a special operation (for example, Control-Alt-Delete
Control-Alt-Delete
Control-Alt-Delete is a computer keyboard command on IBM PC compatible systems that can be used to reboot the computer, and summon the task manager or Windows Security in more recent versions of the Microsoft Windows operating system...
); similar to the Shift key
Shift key
The shift key is a modifier key on a keyboard, used to type capital letters and other alternate "upper" characters. There are typically two shift keys, on the left and right sides of the row below the home row...
, the Control key rarely performs any function when pressed by itself. The control key is located on or near the bottom left side of most keyboards, with many featuring an additional one at the bottom right. It is usually labeled Ctrl, but sometimes Control or Ctl is seen, and it can be graphically represented as an “up arrowhead” (U+2303), or simulated with a caret
Caret
Caret usually refers to the spacing symbol ^ in ASCII and other character sets. In Unicode, however, the corresponding character is , whereas the Unicode character named caret is actually a similar but lowered symbol: ....
(^).
History
Keyboard (computing)
In computing, a keyboard is a typewriter-style keyboard, which uses an arrangement of buttons or keys, to act as mechanical levers or electronic switches...
, holding down the Control key while pressing another key zeroed the leftmost 2 bit
Bit
A bit is the basic unit of information in computing and telecommunications; it is the amount of information stored by a digital device or other physical system that exists in one of two possible distinct states...
s of the 7 bits in the generated ASCII
ASCII
The American Standard Code for Information Interchange is a character-encoding scheme based on the ordering of the English alphabet. ASCII codes represent text in computers, communications equipment, and other devices that use text...
character. This allowed the operator to produce the first 32 characters in the ASCII table. These are non-printing characters that signal the computer to control where the next character will be placed on the display device
Display device
A display device is an output device for presentation of information in visual or tactile form...
, eject a printed page or erase the screen, ring the terminal bell, or some other operation. Aptly, these characters are also called control character
Control character
In computing and telecommunication, a control character or non-printing character is a code point in a character set, that does not in itself represent a written symbol.It is in-band signaling in the context of character encoding....
s.
Using the Control key with either lowercase c or uppercase C will generate the same ASCII code on a teletypewriter because holding down the control key grounds
Ground (electricity)
In electrical engineering, ground or earth may be the reference point in an electrical circuit from which other voltages are measured, or a common return path for electric current, or a direct physical connection to the Earth....
(zeros the voltage on) the 2 wires used to carry the leftmost 2 bits from the keyboard. In modern computers, the interpretation of keypresses is generally left to the software. Modern keyboards distinguish each physical key from every other and report all keypresses and releases to the controlling software. This additional flexibility is not often taken advantage of and it usually does not matter, for example, whether the control key is pressed in conjunction with an upper or a lower case character.
When the original purpose of the ASCII control characters became either obsolete or seldom used, later software appropriated the Control key combinations for other purposes.
Because on older keyboards the Control key was located on the left of the keyboard, some people remap the keys to exchange Control and Caps Lock
Caps lock
Caps lock is a key on many computer keyboards. Pressing it sets an input mode in which typed letters are uppercase by default. The keyboard remains in caps lock mode until the key is pressed again...
, finding the traditional location more ergonomic for using programs benefiting from use of the Control key. This is sometimes called a "Unix" layout. Keyboards from Sun Microsystems
Sun Microsystems
Sun Microsystems, Inc. was a company that sold :computers, computer components, :computer software, and :information technology services. Sun was founded on February 24, 1982...
came in two layouts; Unix and PC-style, with the Unix layout having the traditional placing of the Control key and other keys. The OLPC XO-1
OLPC XO-1
The XO-1, previously known as the $100 Laptop, Children's Machine, and 2B1, is an inexpensive subnotebook computer intended to be distributed to children in developing countries around the world, to provide them with access to knowledge, and opportunities to "explore, experiment and express...
keyboard also has the Control key in this location. Keyboards for different computer systems with this placement of the Control key are also sold as extra peripherals, see for example the Happy Hacking Keyboard
Happy Hacking Keyboard
The Happy Hacking Keyboard is a small computer keyboard produced by PFU Limited of Japan, co-developed with Japanese computer pioneer Eiiti Wada...
. After the Mac OS became a Unix based OS, a keyboard-preference setting was added specifically to address this need.
Others leave the control key in the lower-left corner of the keyboard, and press it using the side of their palm. The choice of location for the control key often comes down to the typist's hand shape and posture.
Notation
There are several common notations for pressing the Control key in conjunction with another key. Each notation below means press and hold Control while pressing the x key:| ^X | Traditional notation |
| C-x | Emacs Emacs Emacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively... notation |
| CTRL-X | Old Microsoft Microsoft Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions... notation |
| Ctrl+X | New Microsoft notation |
| Ctrl/X | OpenVMS OpenVMS OpenVMS , previously known as VAX-11/VMS, VAX/VMS or VMS, is a computer server operating system that runs on VAX, Alpha and Itanium-based families of computers. Contrary to what its name suggests, OpenVMS is not open source software; however, the source listings are available for purchase... notation |
Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
and Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
uses the Traditional notation in menus.
Examples
Different application programs, user interfaces, and operating systems use the various control key combinations for different purposes.| Key combination | Microsoft Windows Microsoft Windows Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal... /KDE KDE KDE is an international free software community producing an integrated set of cross-platform applications designed to run on Linux, FreeBSD, Microsoft Windows, Solaris and Mac OS X systems... /GNOME GNOME GNOME is a desktop environment and graphical user interface that runs on top of a computer operating system. It is composed entirely of free and open source software... |
Unix Unix Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna... (command line and programs using readline) |
Emacs Emacs Emacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively... (if different from Unix command line) |
|---|---|---|---|
| Ctrl+A | Select all | Beginning of line | |
| Ctrl+B | Bold | Backward one character | |
| Ctrl+C Control-C Control-C is a common computer command. It is generated by pressing the key while holding down the key on a computer keyboard.In graphical user interface environments that use the control key to control the active program, control-C is often used to copy highlighted text to the clipboard... |
Copy (can also be used as an alternative to Ctrl+Break to terminate an application) | terminate application Break Break may refer to:* Break * Recess , a general term for a period of time in which a group of people is temporarily dismissed from its duties* Break , time off during a shift... |
Compound command |
| Ctrl+D | Font Window (Word Processing); Add to bookmarks (Browsers Web browser A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content... ) |
Forward delete, or if line is empty, end of input (traditional Unix) | Forward delete |
| Ctrl+E | Center Alignment (Word Processing) | End of line | |
| Ctrl+F | Find (usually a small piece of text in a larger document) | Forward one character | |
| Ctrl+G | Go To (Line number) | Bell | Quit - aborts current operation |
| Ctrl+H | Replace, or History in browsers | Delete previous character | Help key |
| Ctrl+I | Italic (sometimes incremental search) | Command line completion Command line completion Command line completion is a common feature of command line interpreters, in which the program automatically fills in partially typed commands.... |
Same as Tab key Tab key Tab key on a keyboard is used to advance the cursor to the next tab stop.- Origin :The word tab derives from the word tabulate, which means "to arrange data in a tabular, or table, form"... |
| Ctrl+J | Justify | Line feed Newline In computing, a newline, also known as a line break or end-of-line marker, is a special character or sequence of characters signifying the end of a line of text. The name comes from the fact that the next character after the newline will appear on a new line—that is, on the next line below the... (LFD) |
LFD (to evaluate Lisp expressions) |
| Ctrl+K | Insert Hyperlink (Word 2007) | Cut ("Kill") text between cursor and end of line | |
| Ctrl+L | Create List, Left align (word processing) | Clear screen | Redraw window/terminal, and recenter view around current line |
| Ctrl+M | Decrease margin by 1/2 inch (Microsoft Word) | Same as Enter key Enter key In computer keyboards, the enter key in most cases causes a command line, window form, or dialog box to operate its default function... |
|
| Ctrl+N | New (window Window (computing) In computing, a window is a visual area containing some kind of user interface. It usually has a rectangular shape that can overlap with the area of other windows... , document, etc.) |
Next line (in history) | Next line |
| Ctrl+O | Open | Flush output | Insert ("open") new line |
| Ctrl+P | Previous line (in history) | Previous line | |
| Ctrl+Q | Quit application | Resume transmission | Literal insert |
| Ctrl+R | Refresh page, Right align (word processing) | Search backwards in history | Search backwards |
| Ctrl+S | Save | Pause transmission | Search forward |
| Ctrl+T | Open New Tab | Transpose characters | |
| Ctrl+U | Underline | Delete text between beginning of line and cursor | Prefix numerical argument to next command |
| Ctrl+V Control-V In computing, Control-V is a control character in ASCII code, also known as the synchronous idle character. It is generated by pressing the key while holding down the key on a computer keyboard... |
Paste | Literal insert | Page down |
| Ctrl+W | Close window or tab Tab (GUI) In the area of graphical user interfaces , a tabbed document interface is one that allows multiple documents to be contained within a single window, using tabs as a navigational widget for switching between sets of documents... |
Delete previous word | Cut |
| Ctrl+X Control-X In computing, control-X is a control character in ASCII code, also known as the cancel character. It is generated by pressing the key while holding down the key on a computer keyboard... |
Cut | Compound command | |
| Ctrl+Y Control-Y For some Microsoft Windows computer applications, the key combination will redo a previous action that the user chose to undo. usually does not have this meaning in the Apple Macintosh operating system, where often does it.... |
Redo (sometimes Ctrl+Shift+Z is used for this) | Paste Cut and paste In human-computer interaction, cut and paste and copy and paste offer user-interface interaction techniques for transferring text, data, files or objects from a source to a destination. Most ubiquitously, users require the ability to cut and paste sections of plain text... |
|
| Ctrl+Z Control-Z In computing, is a control character in ASCII code, also known as the substitute character or a keyboard shortcut. Strictly speaking, is not a printable character at all but a code for control purposes, though it is sometimes rendered by two characters as ^Z. It is generated by pressing the key... |
Undo Undo Undo is a command in many computer programs. It erases the last change done to the document reverting it to an older state. In some more advanced programs such as graphic processing, undo will negate the last command done to the file being edited.... |
Suspend program | Iconify Icon (computing) A computer icon is a pictogram displayed on a computer screen and used to navigate a computer system or mobile device. The icon itself is a small picture or symbol serving as a quick, intuitive representation of a software tool, function or a data file accessible on the system. It functions as an... window Window (computing) In computing, a window is a visual area containing some kind of user interface. It usually has a rectangular shape that can overlap with the area of other windows... |
| Ctrl+[ | Decrease font size | Same as Esc key Esc key On computer keyboards, the Esc key is a key labeled Esc or Escape that is used to generate the ASCII Escape character , the character code traditionally used to initiate an escape sequence... |
Same as Modifier key Modifier key In computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination.... (Alt key Alt key The Alt key on a computer keyboard is used to change the function of other pressed keys. Thus, the Alt key is a modifier key, used in a similar fashion to the Shift key. For example, simply pressing "A" will type the letter a, but if you hold down either Alt key while pressing A, the computer... ) |
| Ctrl+End | Bottom (end of document or window Window (computing) In computing, a window is a visual area containing some kind of user interface. It usually has a rectangular shape that can overlap with the area of other windows... ) |
undefined or rarely used | Bottom (end of text buffer) |
| Ctrl+Home | Top (start of document or window Window (computing) In computing, a window is a visual area containing some kind of user interface. It usually has a rectangular shape that can overlap with the area of other windows... ) |
undefined or rarely used | Top (start of text buffer) |
| Ctrl+Ins | Copy | undefined or rarely used | Copy |
| Ctrl+PgDn | Next tab Tab (GUI) In the area of graphical user interfaces , a tabbed document interface is one that allows multiple documents to be contained within a single window, using tabs as a navigational widget for switching between sets of documents... |
undefined or rarely used | Scroll window to the right |
| Ctrl+PgUp | Previous tab Tab (GUI) In the area of graphical user interfaces , a tabbed document interface is one that allows multiple documents to be contained within a single window, using tabs as a navigational widget for switching between sets of documents... |
undefined or rarely used | Scroll window to the left |
| Ctrl+Tab | Next window Window (computing) In computing, a window is a visual area containing some kind of user interface. It usually has a rectangular shape that can overlap with the area of other windows... or tab Tab (GUI) In the area of graphical user interfaces , a tabbed document interface is one that allows multiple documents to be contained within a single window, using tabs as a navigational widget for switching between sets of documents... |
undefined or rarely used | |
| Ctrl+Shift+Tab | Previous window Window (computing) In computing, a window is a visual area containing some kind of user interface. It usually has a rectangular shape that can overlap with the area of other windows... or tab Tab (GUI) In the area of graphical user interfaces , a tabbed document interface is one that allows multiple documents to be contained within a single window, using tabs as a navigational widget for switching between sets of documents... |
undefined or rarely used | |
| Ctrl + ← | Previous word | undefined or rarely used | Previous word |
| Ctrl + → | Next word | undefined or rarely used | Next word |
| Ctrl+Delete | Delete Next word | undefined or rarely used | Delete Next word |
| Ctrl+Backspace | Delete Previous word | undefined or rarely used | Delete Previous word |
| Ctrl+Alt+Backspace | undefined or rarely used | Restart X11 | undefined or rarely used |
| Ctrl + Alt + ↑ | Rotate Screen Upside down | unknown | unknown |
| Ctrl + Alt + ↓ | Rotate Screen Right side up | unknown | unknown |
| Ctrl + Alt + ← | Rotate Screen left | unknown | unknown |
| Ctrl + Alt + → | Rotate Screen right | unknown | unknown |
| Ctrl+Shift+Esc | Task Manager | unknown | unknown |
| Ctrl+Alt+Delete Control-Alt-Delete Control-Alt-Delete is a computer keyboard command on IBM PC compatible systems that can be used to reboot the computer, and summon the task manager or Windows Security in more recent versions of the Microsoft Windows operating system... |
Windows Security/Task Manager | Reboot (when on the console) | undefined or rarely used |
Similar concepts
Generally, the Command keyCommand key
The Command key, also historically known as the Apple key, open-Apple key or meta key is a modifier key present on Apple Keyboards. The Command key's purpose is to allow the user to enter keyboard shortcut commands to GUI applications...
, labeled with the symbol on Apple Macintosh computers, performs the equivalent functions in Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
and Mac OS
Mac OS
Mac OS is a series of graphical user interface-based operating systems developed by Apple Inc. for their Macintosh line of computer systems. The Macintosh user experience is credited with popularizing the graphical user interface...
applications (for example, copies, while prints; the same holds for saving, cutting, and pasting).
Macintosh
Macintosh
The Macintosh , or Mac, is a series of several lines of personal computers designed, developed, and marketed by Apple Inc. The first Macintosh was introduced by Apple's then-chairman Steve Jobs on January 24, 1984; it was the first commercially successful personal computer to feature a mouse and a...
es also have a Control key, but it has different functionality. The original Apple mouse design reduced complexity by only offering one button. As the interface developed, Contextual Menus were offered to access extra options. Another button was needed to access these. On Unix and Windows, the user had other mouse buttons to use. On Mac OS, the Control key was used to invoke a "right-click". Apple calls this a "secondary click" as left-handers can choose which side this button is on.
- It is mostly used as a modifier keyModifier keyIn computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....
for key-combinations. - When pressing Control and clicking the mouse-button, you will get a contextual menu. This is a compatibility feature for users with one-button mice; users with two-button mice just use the right mouse-button, with no modifiers.
- It is used in the command line interface with programs made for that interface.
- In Quickbooks, the Control Key is used to validate login credentials during OLSU 1016 and OLSU 1013 errors. Keeping it depressed while sending information to the Quickbooks servers fixes the errors.
- Under Mac OS XMac OS XMac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
, the Control key allows the use of EmacsEmacsEmacs is a class of text editors, usually characterized by their extensibility. GNU Emacs has over 1,000 commands. It also allows the user to combine these commands into macros to automate work.Development began in the mid-1970s and continues actively...
-style key combinations in most text entry fields. For example, Ctrl-A moves the caret to the start of the paragraph, Ctrl-L vertically centers the current line in the editing field, Ctrl-K cuts text to the end of the line to a kill ring separate from the normal clipboardClipboard (software)The clipboard is a software facility that can be used for short-term data storage and/or data transfer between documents or applications, via copy and paste operations...
, etc.
See also
- Alt keyAlt keyThe Alt key on a computer keyboard is used to change the function of other pressed keys. Thus, the Alt key is a modifier key, used in a similar fashion to the Shift key. For example, simply pressing "A" will type the letter a, but if you hold down either Alt key while pressing A, the computer...
- Break keyBreak keyThe origins of the break key on a computer keyboard go back to telegraph practices. A standard telegraph key has a built-in knife switch that can be used to short the key's contacts. When the key was not in use, that switch was kept closed, so that a signal was continually sent...
- Control characters
- Control-Alt-DeleteControl-Alt-DeleteControl-Alt-Delete is a computer keyboard command on IBM PC compatible systems that can be used to reboot the computer, and summon the task manager or Windows Security in more recent versions of the Microsoft Windows operating system...
- Function keyFunction keyA function key is a key on a computer or terminal keyboard which can be programmed so as to cause an operating system command interpreter or application program to perform certain actions...
- Keyboard layoutKeyboard layoutA keyboard layout is any specific mechanical, visual, or functional arrangement of the keys, legends, or key–meaning associations of a computer, typewriter, or other typographic keyboard....
- Modifier keyModifier keyIn computing, a modifier key is a special key on a computer keyboard that modifies the normal action of another key when the two are pressed in combination....