Control-Z
Encyclopedia
In computing
, is a control character
in ASCII code, also known as the substitute (SUB
) 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 while holding down the key on a computer keyboard
. The equivalent Mac OS
and Mac OS X
key combination on Apple computers is .
In many GUIs and applications can be used to undo the latest action. In some applications earlier actions than the last one can be undone by clicking multiple times. was one of a handful of keyboard
sequences chosen by the program desiqwerewrgners at Xerox PARC
to control text editing
. Presumably these particular keystrokes were chosen because of their location on a standard QWERTY keyboard, since the Z (undo), X
(cut), C
(copy), and V
(paste) keys are located together at the left end of the bottom row of the standard QWERTY
keyboard.
In some operating systems, is used to signal an end-of-file
, and thus known as the EOF
character (more accurately: the EOF control code), when typing at a terminal, terminal emulator
, MS-DOS
command line, or Win32 console
. Early DEC
operating systems used this convention, which was borrowed by CP/M
, and was later in turn borrowed and continued in the MS-DOS and Microsoft Windows
operating systems.
On Unix-like
systems, is the most common default keyboard mapping for the key sequence that suspends
a process
(SIGTSTP
). When entered by a user at their computer terminal
, the currently running foreground process is sent a SIGTSTP
signal, which generally causes the process to suspend its execution. The user can later continue the process execution by typing the command 'fg
' (short for foreground) or by typing 'bg
' (short for background
) and furthermore typing the command 'disown' to separate the background process from the terminal.
On Blogger
, a weblog publishing service
, the shortcut actually replaces the current version with the one last saved automatically.
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...
, is a 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....
in ASCII code, also known as the substitute (SUB
Substitute character
A substitute character is a control character that is used in the place of a character that is recognized to be invalid or in error or that cannot be represented on a given device....
) character or a keyboard shortcut
Keyboard shortcut
In computing, a keyboard shortcut is a finite set of one or more keys that invoke a software or operating system operation when triggered by the user. A meaning of term "keyboard shortcut" can vary depending on software manufacturer...
. Strictly speaking, is not a printable character at all but a code for control purposes
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....
, though it is sometimes rendered by two characters as ^Z. It is generated by pressing the key while holding down the key on a computer keyboard
Computer keyboard
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...
. The equivalent 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...
key combination on Apple computers is .
In many GUIs and applications can be used to undo the latest action. In some applications earlier actions than the last one can be undone by clicking multiple times. was one of a handful of keyboard
Computer keyboard
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...
sequences chosen by the program desiqwerewrgners at Xerox PARC
Xerox PARC
PARC , formerly Xerox PARC, is a research and co-development company in Palo Alto, California, with a distinguished reputation for its contributions to information technology and hardware systems....
to control text editing
Text editor
A text editor is a type of program used for editing plain text files.Text editors are often provided with operating systems or software development packages, and can be used to change configuration files and programming language source code....
. Presumably these particular keystrokes were chosen because of their location on a standard QWERTY keyboard, since the Z (undo), 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), 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), and 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) keys are located together at the left end of the bottom row of the standard QWERTY
QWERTY
QWERTY is the most common modern-day keyboard layout. The name comes from the first six letters appearing in the topleft letter row of the keyboard, read left to right: Q-W-E-R-T-Y. The QWERTY design is based on a layout created for the Sholes and Glidden typewriter and sold to Remington in the...
keyboard.
In some operating systems, is used to signal an end-of-file
End-of-file
In computing, end of file is a condition in a computer operating system where no more data can be read from a data source...
, and thus known as the EOF
End-of-file
In computing, end of file is a condition in a computer operating system where no more data can be read from a data source...
character (more accurately: the EOF control code), when typing at a terminal, terminal emulator
Terminal emulator
A terminal emulator, terminal application, term, or tty for short, is a program that emulates a video terminal within some other display architecture....
, MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
command line, or Win32 console
Win32 console
Win32 console is a text user interface implementation within the system of Windows API, which runs console applications. A Win32 console has a screen buffer and an input buffer, and is available both as a window or in text mode screen, with switching back and forth available via Alt-Enter...
. Early DEC
Digital Equipment Corporation
Digital Equipment Corporation was a major American company in the computer industry and a leading vendor of computer systems, software and peripherals from the 1960s to the 1990s...
operating systems used this convention, which was borrowed by CP/M
CP/M
CP/M was a mass-market operating system created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc...
, and was later in turn borrowed and continued in the MS-DOS and 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...
operating systems.
On Unix-like
Unix-like
A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....
systems, is the most common default keyboard mapping for the key sequence that suspends
Process states
In a multitasking computer system, processes may occupy a variety of states. These distinct states may not actually be recognized as such by the operating system kernel, however they are a useful abstraction for the understanding of processes....
a process
Process (computing)
In computing, a process is an instance of a computer program that is being executed. It contains the program code and its current activity. Depending on the operating system , a process may be made up of multiple threads of execution that execute instructions concurrently.A computer program is a...
(SIGTSTP
SIGTSTP
SIGTSTP is a signal in a Unix computer system that tells a program to stop temporarily. On POSIX-compliant platforms, SIGTSTP is the signal sent to a process by its controlling terminal when the user requests that the process be suspended. The symbolic constant for SIGTSTP is defined in the header...
). When entered by a user at their computer terminal
Computer terminal
A computer terminal is an electronic or electromechanical hardware device that is used for entering data into, and displaying data from, a computer or a computing system...
, the currently running foreground process is sent a SIGTSTP
SIGTSTP
SIGTSTP is a signal in a Unix computer system that tells a program to stop temporarily. On POSIX-compliant platforms, SIGTSTP is the signal sent to a process by its controlling terminal when the user requests that the process be suspended. The symbolic constant for SIGTSTP is defined in the header...
signal, which generally causes the process to suspend its execution. The user can later continue the process execution by typing the command 'fg
Fg (Unix)
fg is a job control command in Unix and Unix-like operating systems that resumes execution of a suspended process by bringing it to the foreground and thus redirecting its standard input and output streams to the user's terminal...
' (short for foreground) or by typing 'bg
Bg (Unix)
bg is a job control command in Unix and Unix-like operating systems that resumes execution of a suspended process without bringing it to the foreground; the resumed process continues to execute in the background without receiving user input from the terminal. bg is required to be included in an...
' (short for background
Background (computer software)
A background process is a computer process that runs "behind the scenes" and without user intervention. Typical tasks for these processes include logging, system monitoring, scheduling, and user notification....
) and furthermore typing the command 'disown' to separate the background process from the terminal.
On Blogger
Blogger
Blogger may refer to:* A person who writes a blog, or weblog* Blogger , a web service for publishing blogs...
, a weblog publishing service
Weblog software
Weblog software is software designed to simplify the creation and maintenance of weblogs...
, the shortcut actually replaces the current version with the one last saved automatically.
Representation
- ASCIIASCIIThe 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...
and UnicodeUnicodeUnicode is a computing industry standard for the consistent encoding, representation and handling of text expressed in most of the world's writing systems...
representation of "substitute":- Octal code: 32
- Decimal code: 26
- Hexadecimal code: 1A, U+001A
- Mnemonic symbol: SUBSubstitute characterA substitute character is a control character that is used in the place of a character that is recognized to be invalid or in error or that cannot be represented on a given device....
- Binary value: 11010
See also
- Access key
- C0 and C1 control codesC0 and C1 control codesMost character encodings, in addition to representing printable characters, may also represent additional information about the text, such as the position of a cursor, an instruction to start a new line, or a message that the text has been received...
(ISO 646) - Control-CControl-CControl-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...
- Control-G
- Control-VControl-VIn 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...
- Control-XControl-XIn 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...
- Control-\