To shut down or power off a computer is to remove power from a computer's main components in a controlled way. After a computer is shut down, main components such as

CPU A central processing unit (CPU), also called a central processor, main processor, or just processor, is the primary processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, log ...

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modules and

hard disk drive A hard disk drive (HDD), hard disk, hard drive, or fixed disk is an electro-mechanical data storage device that stores and retrieves digital data using magnetic storage with one or more rigid rapidly rotating hard disk drive platter, pla ...

s are powered down, although some internal components, such as an internal clock, may retain power.

Implementations

The shutdown feature and

command Command may refer to: Computing * Command (computing), a statement in a computer language * command (Unix), a Unix command * COMMAND.COM, the default operating system shell and command-line interpreter for DOS * Command key, a modifier key on A ...

is available in

Microsoft Microsoft Corporation is an American multinational corporation and technology company, technology conglomerate headquartered in Redmond, Washington. Founded in 1975, the company became influential in the History of personal computers#The ear ...

Windows Windows is a Product lining, product line of Proprietary software, proprietary graphical user interface, graphical operating systems developed and marketed by Microsoft. It is grouped into families and subfamilies that cater to particular sec ...

ReactOS ReactOS is a Free and open-source software, free and open-source operating system for i586/amd64 personal computers that is intended to be binary-code compatibility, binary-compatible with computer programs and device drivers developed for Wind ...

, HP MPE/iX, and in a number of

Unix Unix (, ; trademarked as UNIX) is a family of multitasking, multi-user computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, a ...

and

Unix-like A Unix-like (sometimes referred to as UN*X, *nix or *NIX) operating system is one that behaves in a manner similar to a Unix system, although not necessarily conforming to or being certified to any version of the Single UNIX Specification. A Uni ...

operating systems such as

Apple An apple is a round, edible fruit produced by an apple tree (''Malus'' spp.). Fruit trees of the orchard or domestic apple (''Malus domestica''), the most widely grown in the genus, are agriculture, cultivated worldwide. The tree originated ...

macOS.

Microsoft Windows and ReactOS

In Microsoft Windows and

, a PC or server is shut down by selecting the item from the Start menu on the desktop. Options include shutting down the system and powering off, automatically restarting the system after shutting down, or putting the system into standby mode, stand-by mode. Just like other operating systems, Windows has the option to prohibit selected users from shutting down a computer. On a home PC, every user may have the shutdown option, but in computers on large networks (such as Active Directory), an administrator can revoke the access rights of selected users to shut down a Windows computer. Nowadays there are many software utilities which can automate the task of shutting down a Windows computer, enabling automatic computer control. The Windows Shutdown website lists various software utilities to automate the task of shutting down. In Windows, a program can shut down the system by calling the ExitWindowsEx or NtShutdownSystem function.

Command-line interface

There is also a shutdown

that can be executed within a shell (computing), command shell window. shutdown.exe is the command-line interface, command-line shutdown application (located in %windir%\System32\shutdown.exe) that can shut down the user's computer or another computer on the user's network. Different parameters allow different functions. More than one parameter can be used at a time for this command.

Apple macOS

macOS the computer can be shut down by choosing "Shut Down…" from the Apple Menu, by pressing key/button (or key), or by pressing the power key to bring up the power management dialog box and selecting button "Shut down". An administrator may also use the Unix shutdown

as well. It can also be shut down by pressing key/button (or key) or clicking Shut Down on the Apple Menu while holding the key, but this will not prompt the user anything at all. On newer and some older Apple computers, starting with Mac OS 9, the user is given a time limit in which the computer will automatically shut down if the user does not click the "Shut Down" button.

Unix and Linux

and Linux, the shutdown command can be used to turn off or Booting, reboot a computer. Only the superuser or a user with special privileges can shut the system down. One commonly issued form of this command is shutdown -h now, which will shut down a system immediately. Another one is shutdown -r now to reboot. Another form allows the user to specify an exact time or a delay before shutdown: shutdown -h 20:00 will turn the computer off at 8:00 PM, and shutdown -r +1 will automatically reboot the machine in one minute of issuing the command.

References

External links

shutdown Microsoft Docsshutdown.cc
– an article about various ways of automated and manual shutting down of Microsoft Windows {{DEFAULTSORT:Shutdown (Computing) Operating system technology Windows commands Windows administration MacOS Unix process- and task-management-related software