Ctrl alt del

What is ctrl alt del?

Control-Alt-Delete is quite widely abbreviated to Ctrl+Alt+Del, or shortened like this: ctrl alt del. It is often called the "three-finger salute" or "Security Keys." Ctrl alt del is a computer keyboard command right on IBM PC compatible computers, where it is invoked when pressing the "Delete" key and holding the "Control" and "Alt" keys altogether, i.e., Ctrl+Alt+Delete. The ctrl alt del key combination's function varies depending on the context, but this key combination generally facilitates or interrupts or interrupts a process.

For example, in the pre-boot environment right before an operating system starts or even in Windows 3.0, DOS, or earlier versions of Windows and OS/2, the ctrl alt del key combination reboots the computer. Starting with Windows 95, the ctrl alt del key invokes a security-related component or a task manager that facilitates killing a frozen application or ending a Windows session.

A brief history of ctrl alt del

Initially, the soft reboot function through the keyboard was designed by David Bradley. He is known as a developer of the machine's ROM-BIOS, who had initially used the key combination: Ctrl+Alt+Esc. As it is known, he found it too easy to bump the left side of the keyboard and then reboot the computer accidentally. According to Bradley's account, Mel Hallerman was the chief programmer of that project and offered to switch the key combination into Ctrl+Alt+Del as a safety measure.

The ctrl alt del feature was initially conceived only as a development feature for its internal use and not intended to be used by end-users since it triggered the reboot even without any alter, warning or confirmation. The key was designed for people writing documentation or programs to reboot their computers without powering the device down.

Ctrl alt del across different platforms

Ctrl alt del key combination is used in different platforms and devices, but it is noteworthy to mention that the name and the design of these keys may be slightly or entirely other. Below, you will find interesting and helpful information about the ctrl alt del key combination use across different platforms.

In Mac – On macOS, the key combination of Ctrl+Alt+Delete does not appear to be a keyboard shortcut. Instead, Mac uses ⌘ Command+⌥ Option+Esc key, which brings up the Force Quit panel. The Control+⌘ Command+Power key restarts the computer.

The initial Mac OS X Server used an Easter egg in which the user had to press the Control+⌥ Option+Delete since the Option key was the equivalent to the Alt key on a Mac keyboard so that it would show an alert warning: "This is not DOS!". In macOS use can use the following key buttons instead of ctrl alt del:

  • ⌥ Option+⌘ Command+Esc function is to force quit applications.
  • ⌘ Cmd+⌃ Control+⏏ Media Eject function is to quit all apps and restart the device.
  • ⌘ Cmd+⌥ Option+⌃ Control+⏏ Media Eject function is to stop all apps and shut down the machine.
  • Control+⏏ Media Eject function is to sleep, show restart, or shutdown dialog.
  • Control+⌘ Command+Power function is to restart the device immediately.

In Windows:

  • Windows 3.x Ctrl+Alt+Delete key function is to close unresponsive apps. The key, if pressed twice, performs a soft reboot.
  • Windows 9x Ctrl+Alt+Delete key function is to bring up the "Close Program" dialog box and, if pressed twice, perform a soft reboot.
  • Windows NT family Ctrl+⇧ Shift+Esc function is to bring up the Windows Task Manager.

In Windows NT:

  • Ctrl+Alt+Delete key button before login function brings up the login screen (also called a secure attention sequence); After logon, the process is to bring up Windows Security. E.g., if the welcome screen is enabled in Windows XP, the key combination brings up the Windows Task Manager. Otherwise, it brings up Windows Security.

In Linux:

  • Linux Ctrl+Alt+Delete, the function of ctrl alt del in Linux, signals the init process (typically configured to soft reboot) Alt+SysRq+function key. The Magic SysRq key function performs a specific low-level function, depending on the key role. Eg., reboot (forced soft reboot), sync (flush caches), unmount (remount filesystems read-only), etc.

In the X Window System:

  • Ctrl+Alt+← Backspace role is to immediately kill the X server (note that the key can be disabled). While using an X Display Manager, the ctrl alt button will regularly start the X server again.


  • The Ctrl+Alt+Delete key combination role is to perform a soft reboot without memory initialization through jumping into IPL reset vector, right after broadcasting a pending shutdown event of the device (usually on AT compatible machines).