up vote 4 down vote favorite
share [g+] share [fb]

Is there any command by which I may shutdown my system instantly?

link|improve this question
71% accept rate
21  
Flipping the power switch at the wall. – Sam152 Feb 14 '10 at 11:51
Sam152: One and done. – Urda Feb 14 '10 at 19:56
1  
@Sam152: sudo flipping the power switch at the wall. ;) – Bobby Feb 16 '10 at 9:18
feedback

migrated from stackoverflow.com Feb 14 '10 at 11:52

This question came from our site for professional and enthusiast programmers.

6 Answers

up vote 8 down vote 
sudo shutdown -h now
link|improve this answer
That wouldn't shutdown a system instantly. ;) – Marcel Korpel Feb 14 '10 at 11:57
8  
@Marcel Korpel: As instantly as one should do without damaging his system ;) – Felix Feb 14 '10 at 12:05
@Felix - I keep hearing that Linux is a very robust system, and it can't handle the same "hard reboots" as my Windows endured? Would be surprising ;) – Gnoupi Feb 16 '10 at 9:57
@Gnoupi: No OS can be built without some vulnerability to abrupt shutdown. Otherwise, the answer to the fastest shutdown method would be to yank the power cord. – harrymc Feb 16 '10 at 11:03
1  
Some versions the syntax is different. "sudo shutdown -g0 -y -i5" (Solaris). And of course, just to make it difficult, the exact value following "i" can be different for shutdown on different systems. I believe it's 0 on a lot of other systems for shutdown. Sigh. Gotta love standards, so many to choose from! – Brian Knoblauch Feb 16 '10 at 13:34
show 1 more comment
feedback
up vote 3 down vote

Hold the power key for about 4 seconds, it's quite fast.

link|improve this answer
If doing so, flipping the power switch is actually faster ;) – Gnoupi Feb 16 '10 at 9:58
That's the same as any other shutdown method, assuming that the OS does power management. – harrymc Feb 16 '10 at 11:04
1  
If you actually can't wait a few seconds, and are going to kill power, use a journaling filesystem like ext3/ext4 so you don't lose as much data due to unwritten writes. – CarlF Feb 16 '10 at 11:33
feedback
up vote 2 down vote 
poweroff

This should work on most common distros. Unlike with shutdown, on many systems you can execute this as a normal user (no sudo needed).

link|improve this answer
feedback
up vote 2 down vote

On certain linux distributions, shutdown offers the option -n. (See man shutdown). Certain distributions (such as ubuntu which makes use of upstart instead of sysvinit) don't support his flag however, and this flags is (as can be learned from the manpage) not without risk. Though I've been using this for years (on my laptop i don't care that all daemons are terminated properly, it just want everything killed and my diskcache flushed) (it is faster than a regular shutdown, and more safe than pulling the plug (and friends ) ). You could see if this solves your problem.

link|improve this answer
feedback
up vote 1 down vote

You've got to use the Magic SysRq key combination REISUB.

Repeat after me: "Raising Elephants Is So Utterly Boring..."

link|improve this answer
No. REISUB will restart it. REISUO will shutdown. Or simply O. – Benoit Nov 22 '10 at 20:19
feedback
up vote 0 down vote

halt is pretty quick.

link|improve this answer
On some systems it's known as "haltsys" rather than just "halt". – Brian Knoblauch Feb 16 '10 at 13:35
feedback

Your Answer

 
or
required, but never shown

Not the answer you're looking for? Browse other questions tagged or ask your own question.