Clamp grip

from Wikipedia, the free encyclopedia
The standard key combination "Ctrl-Alt-Del" can only be reached with two hands, but the one-handed AltGr + Ctrl (right) + Del combination has the same effect in several operating systems.
The one-handed AltGr + Ctrl (right) + Del combination.

Users of personal computers and other computer systems described in IT jargon tight grip , monkey grip or (because of the weird hands Attitude) Geier handle or vulture's claw (short claw ), the key combination Strg + Alt+ Entf( Ctrl+ Alt+ Del), with the unresponsive ( crashed ) programs can be closed or the computer can be restarted warm . This key combination can usually only be reached with both hands in order to make it more difficult to press it inadvertently. As a rule, the key combination calls up an administrative function of the operating system or the graphical user interface that helps to rectify the fault.

MS-DOS and Windows

The term developed from the combination Strg+ Alt+ Entf, for the first time on IBM PCs under PC DOS or MS-DOS . The key combination is integrated in the PC BIOS and is therefore independent of the operating system. It is also possible early in the start sequence, even before the operating system starts, to restart a stuck PC using this key combination, which triggers a warm start (in contrast to a cold start ). An operating system on an IBM-compatible PC must redirect the BIOS function to prevent an uncontrolled restart. PC compatible DOS makes this usually not because it does not use a write cache and an unhooking ( English unmount file systems is not necessary). More modern operating systems such as Unix or Unix-like systems , but also Windows from Microsoft from the Windows 9x and Windows NT lines , usually write data to a data storage device such as a hard disk before a warm start is triggered and manage the BIOS Function to a function of the operating system. In the event of a serious error, a core dump can also be saved.

When developing the IBM PC, David Bradley , a computer science engineer, originally intended the Strg+ Alt+ combination Escfor it, but it was too easy to accidentally press it, for example if you slip your hand on the left side of the keyboard . The combination Strg+ Alt+ Entfwas then chosen because you can hardly press it accidentally. On older keyboards that only had Ctrl and Alt keys on the left, it could only be triggered with two hands; On newer keyboards, the same function can also be triggered with one hand with Strg+ AltGr+ Entfif the AltGr key is also interpreted as Alt (which the PC BIOS does, but not every operating system).

The exact function of Strg+ Alt+ Entfdepends heavily on the particular operating system. Under OS / 2 , like MS-DOS, the computer is restarted without a prompt, but OS / 2 does some cleaning up beforehand. In Windows NT, the use of the key combination depends on the context. The system could be configured in such a way that + + had to be pressed before logging in , which was supposed to provide additional security and was referred to by Microsoft Secure Attention Sequence , "SAS" for short. However , this is no longer preconfigured for Windows versions from Vista . After logging in, i.e. when a user is logged in and the desktop is already loaded, a comprehensive menu appears after pressing + + with commands for logging out or shutting down the computer, changing the password, calling up the lock of the station, in which the task manager is also opened can. The latter can also be called up directly using the + + key combination . With it you can stop, start and monitor computer programs . Furthermore, it offers the possibility to view the utilization of the processor and the main memory and to trace individual tasks back to processes and thus to open files. The operating system can also be shut down, restarted or switched to standby mode via the task manager . According to Microsoft, this key combination cannot be emulated by any application on the hardware level, and remote maintenance programs such as VNC only send this command to the operating system as an emulated keyboard command. StrgAltEntfStrgAltEntfStrgUmschaltEsc


  • Under DOS , this key combination is recognized by the BIOS, which starts a function that restarts the computer. It is possible to intercept this key combination, which has been done by some hard disk cache programs (for example SmartDrive ) to clear the write cache before the computer is restarted.
  • Under the Windows 9x series, a simple task manager is called up; if you press it again, a restart takes place.
  • In Windows NT and Windows 2000 , the Security dialog box appears.
  • In Windows XP , the Task Manager is displayed if the welcome page is activated, otherwise the "Windows Security" dialog box is displayed.
  • In Windows Vista and Windows 7 , the combination opens a selection page, similar to Windows XP with the welcome page deactivated. You can then open the Task Manager directly with Strg+ Umschalt+ Esc(as with Windows 2000 and XP).
  • In Windows 8 and 8.1 as well as Windows 10 , a selection page is also displayed, which offers the options to open the Task Manager, log out, change the user or open the lock screen . In addition, the regular power-off button, a language selection, the Ease of Access Center and a selection of the available networks are displayed in the lower right corner of the screen.


On IRIX , the monkey handle is Strg+ Shift+ F12+ Num /(i.e. /on the numeric keypad).


More detailed description under Magic S-Down key .
The " S-Abf " ("SysRq") function is an alternative assignment to the "Print Screen" key on IBM AT-compatible keyboards

Linux has several monkey handles. In addition to Strg+ Alt+ Entf, which can directly trigger a reboot in text mode consoles (depending on the required ctrlaltdel entry in / etc / inittab ), there are combinations with the so-called magic S-Abf key . These are with S-Abf+ entsprechende Taste(on English-language keyboards SysRq+ entsprechende Tasteselected), the S-Dep except on some notebooks, an alternative assignment to the key Druck(Engl. PrintScrn), And indeed Alt+ Druck. A clean as possible restart a crashed computer running Linux is retaining Alt+ Druckand during which the successive pressing R, E, I, S, U, Btriggered. Instead, Altyou can also Alt Gruse what is often easier to do with one hand.

In Linux, Strg+ + Altsends Entfa signal to the initprocess, which then executes a configured command (e.g. restart the computer). A local X server , however, intercepts this key combination and allows you to call your own functions. This is used by environments such as KDE or GNOME to display a configurable dialog box that is quite similar to the look and feel of Windows and in some cases offers additional functions.

Linux distributions with systemd version 219 or higher restart when pressed more than 7 times within 2s Strg+ Alt+ Entf.

X Window System

A number of monkey grips are also available under the cross-platform X Window System graphical user interface . The best known of these is possibly Strg+ Alt+ ←   (backspace), which immediately terminates the graphical user interface and all processes running under it. If a display manager is active, the graphical user interface is restarted by the display manager after pressing the key combination and then typically shows a new login screen. On some systems this key combination is disabled; it is controlled by the DontZap and HandleSpecialKeys options in the ServerFlags section of /etc/X11/xorg.conf . Sometimes (e.g. with OpenSUSE ) the X server is configured in such a way that a long beep sounds first as a warning and the X server is only terminated when you press Strg+ Alt+ ←   again.

In order to abort stuck processes , either the key combination Strg+ Alt+ Escfollowed by clicking the appropriate window (this starts the xkill program ) or the key combination Strg+ Esc, which opens a window similar to the Processes tab of the Windows Task Manager .

However, this behavior is completely dependent on the Window Manager used and can vary considerably under certain circumstances. Some window managers do not provide any emergency key combinations at all, so that you often have to switch to a console switch with Strg+ Alt+ F1or F2to F6.


On Macintosh computers, the key combination to quit a single program is:  +  + Esc.

To restart: Simultaneously press ctrl + and the power button (detached key with triangle pointing to the left), on later Macintosh computers (without the power button on the keyboard) ctrl +  + .

Clear parameter RAM : After switching on the computer, keep  +  + P + Rpressed until the start-up sound has been played for the third time, then release the keys. The  +  + N + key combination Vcan be used to reset the content of the NVRAM in the same way .

Apple II

The computers of the older Apple II series (not to be confused with the Macintosh II ) have a Resetkey on the keyboard that directly resets the processor. With all Apple II models except the rare original model, Resethowever, something is only effective if it is Ctrlheld down at the same time (with the Apple II + this can be selected via a slide switch on the inside of the computer on the keyboard board, but is switched on by default). This simple reset by the key combination Ctrl+ Resetcan be intercepted by programs from the Apple II +, it is also intercepted by the standard firmware of the computer and in this case only causes a stop of the possibly running program and a reset of the screen to text mode ; the Apple II + can therefore only be completely restarted by switching it off and on again. From the Apple IIe model, there is also the Ctrl+ Leerer Apfel+ key combination that cannot be intercepted Reset(or Ctrl+ + Reseton the Apple II GS and the Apple IIc +), which triggers a restart without prompting. The key combination Ctrl+ Ausgefüllter Apfel+ Reset(or Ctrl+ + Reset), on the other hand, causes a self-test of the system. On the Apple II GS , the key serves as the Resetkey that serves as the power button on the Macintosh - it is usually marked with a triangle pointing to the left.


On Amiga computers, the monkey handle consists of the key combination Ctrl+ Amiga+ Amiga. This is already recognized by the microcontroller built into the keyboard ; this acts directly on the reset signal of the computer. Depending on the version, the microcontroller has its own connection to the reset signal (e.g. Amiga 500 ), or it generates an otherwise unused signal sequence on the data connection to the computer, which is recognized by a circuit in the computer which generates a reset signal from it ( e.g. Amiga 1000 ). This means that no part of the operating system needs to be running; Interception by the software is only possible by engaging in the boot process .

Commodore 8-bit computer

On the VC 20 , C64 and C128 , the key Restorethat is the only key that is directly connected to the CPU triggers an NMI (non-maskable interrupt), which is normally intercepted by the operating system or the application and therefore has no visible effects. If, however, Restorethe button is Run/Stopheld down while pressing , the operating system performs a kind of soft reset, which halts a running program (but leaves it in the memory), resets the sound and video chips and the other interface modules to the start settings, the screen and takes the user back to the BASIC prompt. This soft reset is only effective if the processor has not crashed and the memory content is still halfway intact. On the old C64 variant in the brown bread box housing, Restorebecause of an incorrectly dimensioned capacitor, it only works if the key is pressed very briefly and forcefully; on the newer C64 and on the other Commodores it can also be pressed normally.

Because Restorein many cases the desired performance is not achieved, many users also install a hardware reset button or connect it externally to the user port or the serial bus ( CBM bus , 6-pin DIN socket ). Since via the serial bus z. B. If the floppy disk drive or printer is connected, these devices are also reset. Later Commodore models already had a hardware reset button on the side ex works. Pressing such a hardware reset button can also be intercepted by appropriately designed programs . In this case , many copy-protected games delete z. B. the memory to complicate the creation of a so-called. Pirate copy .

AS / 400, iSeries, System i

On a 5250 terminal session in the OS / 400 operating system (means from version V5R3 i5 / OS) you can call up the system request menu with the monkey handle Shift+ S-Abf+ Daten Freigabe. There is then the option of canceling the previous program, opening an alternative job (session) or completely logging off the currently running dialog job from the system. The terminal session is only the client, the program runs on the server. In contrast S-Abfto the classic PC keyboard, the key is an extra key at the top left, because the keyboards for the AS / 400 have 122 keys.


See also

Web links

Individual evidence

  1. Enable Press Ctrl + Alt + Del Secure Logon On Windows 7 or Vista. My Digital Life, January 28, 2010, accessed September 3, 2019 .
  2. Interactive login: No CTRL + ALT + DEL required. Microsoft, accessed September 3, 2019 .
  3. Windows Logon Options: Part Two of Two (English)
  4. Secure Attention Sequence (English)
  5. Documentation from the Linux kernel: /usr/src/linux/Documentation/sysrq.txt
  6. [systemd-devel] [ANNOUNCE] systemd 219
  7. ^ X manpage at
  8. Manpage of xorg.conf at
  9. with the VC 20 actually via an interface module, but that does not matter for the functionality described here