Control-Z
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In computing, control-Z is a control character in ASCII code, also known as the substitute (SUB) character. It is generated by pressing the Z key while holding down the Ctrl key on a computer keyboard.
In some operating systems, control-Z is used to indicate end-of-file. Early DEC operating systems used this convention, which was borrowed by CP/M, and was later in turn borrowed and continued in the Microsoft DOS operating system.
Control-Z was one of a handful of keyboard sequences chosen by the program designers at Xerox PARC to control text editing. It is used to undo the last cut-and-paste operation performed by the user. 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 keyboard row. Such usage continues today in many GUI-based operating systems (including Microsoft Windows and Mac OS) and word processing software. Some software programs also provide a keystroke that functions as the opposite redo operation, which re-applies the last editing operation, generally activated by a control-Y or control-shift-Z.
On Unix and Unix-like operating systems, control-Z is the most common default keyboard mapping for the key sequence that suspends a process. 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 or run the process in background mode.
[edit] Summary
- ASCII and Unicode representation of "substitute":
- Octal code: 32
- Decimal code: 26
- Hexadecimal code: 1A, U+001A
- Mnemonic symbol: SUB
