Ctrl-Alt-Del

Key sequence used on x86 machines to force a reboot - unless you are using Windows NT, in which case it is used to log in. Also known as the three finger salute. One of the most frequently used key combinations under Windows&operating systems.

A special key combination used to soft reboot machines running MS-DOS or OS/2. The same combination is used to login to Windows NT or to kill the current task on Windows 9x. On Linux PCs this combination is often tied to the shutdown command. These three keys are used because it's very difficult to hit all three accidentally.

The ultimate problem solving method incase of a BSOD or a freeze in a Microsoft based operating systems.

Allmost used exclusively when all your work is unsaved and critical, rendering frustration and somtimes tears.

Some Linux flavours use this combination as a SIG to actually take the machine down nicely.

That would be Ctrl+Alt+Del, for the Windows tech writer.

Microsoft Windows documentation has tried to offer a new standard way of describing keystrokes in text; it hasn't really converted many people, perhaps because few people who use Windows think of the mouse as an optional device.

The Ctrl-Alt-Del in NT/2k is for security, actually. You can define the login program to run at boot and that could contain some trojan, so microsoft set winnt up to run %WINDIR%\login.exe every time, and the executable must be digitally signed by M$ to run.

So, this all means to you that if your NT box is going down, then at least you know that the l33t h4x0r who did had enough money to pay m$ to sign his program. :)

(Actually, Microsoft will test the program out (highly skilled staff:) before they OK it.)

One of the other features of the Ctrl+Alt+Delete to login is that is the apparent login box is actually a trojan horse running in user space, Windows NT will display the logout box when the user press Ctrl+Alt+Delete instead of the expected login box. My personal opinion is that this is a rather nice feature.

Under Linux (and probably other x86 'NIXes) ctrl+alt+del either, in the "soft" case, sends a SIGINT to the init process which calls whatever is defined in /etc/inittab. In my case:

# Trap CTRL-ALT-DELETE
ca::ctrlaltdel:/sbin/shutdown -t3 -r now

or the "hard" case where it just restarts the system.

A lot of folks were wondering why Microsoft started using the ctrl+alt+del keystroke combination to log on to Windows NT. Pressing these three keys together creates a hardware interrupt, which would stop any other process displayed on the monitor. There were folks who were coming out with little hacks that would capture login screen names and passwords by displaying a fake login screen, but these were all defeated by the ctrl+alt+del combo. It added a little bit of security to the logon process.

Under NT, Ctrl-Alt-Delete is used to get the attention of the core system; no userland app can listen for or issue a Ctrl-Alt-Delete. Unless NT has bluescreened, it promptly pops up a helpful window that can start task manager, change your password, lock the computer, etc. Compare with 9X which may, if it's feeling like it, present a list of non-hidden processes that it may deign to attempt to close.

Why does NT require you to Ctrl-Alt-Delete before doing anything security related? Because only the system responds to a Ctrl-Alt-Delete, you will definitely get the real change password screen, the real lock workstation screen. Trojan Horses won't work, as the real NT dialogue will supplant them. If you've pressed Ctrl-Alt-Delete, you're definitely typing your password into the system, and not a third-party program.

Under linux, incidentally, if /etc/shutdown.allow is present Ctrl-Alt-Delete won't cause a shutdown unless a user specified in it is logged in. Stop random people walking up to your server and rebooting it!

The Macintosh equivalent of control-alt-delete is command-control-power. (Isn't that great? "Command! Control! Power! -- Bring me more; I yet lust for keys!")

Before resorting to that, however, try command-option-escape to bring up the force quit dialog, which sometimes gets rid of the hung application, sometimes gets rid of the hung application but releases bogons into your system, and sometimes doesn't work at all. If you're deserving, the system will be stable enough to draw the dialog naming the offending application, which might, e.g., clue you in to a software conflict.

If you're a hard-core Mac geek with a steady hand and a flinty gaze, try hitting command-power at your next Silent Screen. The very core of the OS will belch up a crude command-line debugger, drawn in an itty-bitty window, at which you can type "g finder" and hit return for unpredictable but occasionally beneficial results. (If you're cool, you've installed MacsBug, which replaces that crude debugger with a merely primitive one.)

If you don't want to remember this stuff, (a) install MacOS X, (b) install Yellow Dog or another PPC Linux, or (c) choose a date not too long after that of your Mac's manufacture and install no software released after it. Otherwise, accept that MacOS Classic, splendid creature though it is, ain't nohow a stable operating system.

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The comic strip Sally Forth once referred to the chord command-option-backspace. It was very possibly the most sad, stupid, pathetic thing ever.