Why doesn't kill work?
David Liguori
liguorid at albany.edu
Fri Jan 28 14:56:58 UTC 2005
Robert Locke wrote:
> On Thu, 2005-01-27 at 21:04 -0500, David Liguori wrote:
>
>>In another thread a user having problems with yum killed it. I am
>>curious how he accomplished that. When I run yum (or any other command,
>>for that matter), it stalls, and I stop it with ctrl-z, the following
>>happens:
>>
>
>
> First question, why are you stopping it with Ctrl-Z?? Ctrl-Z puts it to
> sleep into the background. Why not use Ctrl-C which is the intended
> approach?
>
>
>>[1]+ Stopped yum update
>>[root at tabby ~]# ps
>> PID TTY TIME CMD
>> 6179 pts/0 00:00:00 su
>> 6182 pts/0 00:00:00 bash
>> 6214 pts/0 00:00:21 yum
>> 6220 pts/0 00:00:00 ps
>>[root at tabby ~]# kill 6214
>>[root at tabby ~]# ps
>> PID TTY TIME CMD
>> 6179 pts/0 00:00:00 su
>> 6182 pts/0 00:00:00 bash
>> 6214 pts/0 00:00:21 yum ##still running!
>> 6221 pts/0 00:00:00 ps
>>[root at tabby ~]# exit
>>logout
>>There are stopped jobs. ##still running!
>>[root at tabby ~]#
>
>
> This is working as intended. You are using the kill command correctly
> by sending the default signal first (15), the problem is that you put
> the process to sleep earlier with the Ctrl-Z so it cannot "process" the
> TERM (15) signal that you have sent. You could at this point bring the
> process to the foreground waking it up by using the "fg" command, or you
> could awaken it in the background using the "bg" command. Once the
> process is awake, it will process the signal and go away.
>
> BTW, I would not recommend, as many people are wont to do, and jump onto
> the KILL (9) signal. If your process is still writing things to disk
> (asleep or awake), this signal pulls the proverbial rug out from
> underneath and you run the risk of ending up with corrupted data
> depending on the process. Use the KILL (9) signal only as a last
> resort.
>
> I think most books now say this is the proper order:
>
> Ctrl-C
> kill -15
> kill -9
>
> HTH,
>
> --Rob
>
Thanks for all the help on this.
--
Dave
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