shutdown computer after the halt command

Robison, Dave david.robison at
Tue Feb 8 01:46:41 UTC 2011

Allow me to split hairs here.

I was taught "sync;sync;sync;halt".

One for the father, one for the son, one for the holy spirit.

This, of course, in the days when I/O was slow enough that sync didn't 
have time to finish before the halt, so doing it three times ensured 
your file system shut down cleanly.


On 02/07/11 17:38, Devin Teske wrote:
> On Mon, 2011-02-07 at 19:26 -0600, Adam Vande More wrote:
>> On Mon, Feb 7, 2011 at 7:13 PM, Devin Teske<dteske at>  wrote:
>>          There's no technical reason to avoid using halt directly other
>>          than the
>>          fact that shutdown sends a message to connected users while
>>          halt does
>>          not.
>>          --
>>          Devin
>>          P.S. I welcome the rebuttle as a learning experience if the
>>          above is not
>>          100% accurate and true (but be-warned... I went around the
>>          office
>>          polling _really_ old UNIX hands before making the above
>>          statement).
>> I used to believe that until I was shown I was wrong.  The easiest way
>> to see you're wrong is to drop to ttyv0  then do one of each like a
>> reboot then a shutdown -r now.  In the latter case, you'll
>> notice /etc/rc.d/ and /usr/local/etc/rc.d/ stop scripts being
>> processed but not so in the former.  In both types of shutdowns,
>> everything *should* exit cleanly but processes are terminated with
>> different signals and certain types of applications really need the
>> full rc stop script to end cleanly like HAST and CARP for example.
>> shutdown -r/p is a really good habit to form.
>> FWIW, someone also stated reboot on Linux behaves like shutdown -r now
>> so that I sure contributes to the confusion.
> Thank you very much for the explanation!
> Yes, I (we) had completely forgotten about the shutdown scripts.
> Of course, many of us still remember the days when it standard fare to
> "sync; sync; halt".
> --
> Devin
>> -- 
>> Adam Vande More
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Dave Robison
Sales Solution Architect II
FIS Banking Solutions
510/621-2089 (w)
530/518-5194 (c)
510/621-2020 (f)
daver at
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