Kill -0 kills process

[Vincent Farrugia]

Hello,

How can the above happen? We have a process whereby we wish to check whether it is alive using kill -0 (SIGNULL). Instead, it is killed like a kill -9. How can this be? All other processes are not killed by kill -0, as usual.

Thanks,
Vince

[Steven Sim Kok Leong]

Hi,

This is indeed unusual. You may like to update your system patches in the hope that this is a system bug.

Hope this helps. Regards.

Steven Sim Kok Leong

[Ruediger Noack]

It depends of the programmers code how to handle a signal. Seems in your case the SIGNULL performs an exit.

Ruediger

[Rainer von Bongartz]

The application has it's own signal handler installed.

In an application you can define what to do upon receiving a signal. (using call sigset).

The application has the exit() function installed in its signal handler as a reaction to receiving signal 0.



Regards
Rainer

[Duncan Edmonstone]

I don't think it can be the signal handler in the process, as according to the man page for terminate, it never gets a signal:

SIGNULL (0), the null signal, invokes error checking but no signal is
actually sent. This can be used to test the validity or existence of
pid.

Very strange... what is the process in question?

Duncan

[Carlos Fernandez Riera]

If the process is a shell sig 0 is ERR (syntax error) , and then execute exit from the function ( if any) or script.


See man sh (trap).

HTH

[Vincent Farrugia]

The process is one used by a database software. The machine is new (rp5450) and contains the latest March 2002 patches.

[Deepak Extross]

Hi,

Can you just confirm that a "kill -0" is being used, and not a "kill 0".

[harry d brown jr]

Vince,

You don't have "kill" aliased do you?

Have you tried this manually from the command line on the process, because I'm assuming you have a script that is checking to see if the process is running?

Also, what shell are you using for your script?

live free or die
harry

[Vincent Farrugia]

Hello,

I'm using kill -s 0. Only this process is being killed, the others aren't, so no alias. I tried it on a script and also on the command line. I'm using the normal sh shell.

Vince

[Duncan Edmonstone]

Isn't terminate a built-in in the standard HP-UX POSIX shell? WHat happens if you explicitly specify /usr/bin/terminate instead?

HTH

Duncan

[Ruediger Noack]

May be tusc (an aquivalent to truss) will help you to find out what happens.
Look in this thread where tusc is to download:
http://forums.itrc.hp.com/cm/QuestionAnswer/1,,0x3d9fee3e323bd5118fef0090279cd0f9,00.html

Good luck
Ruediger

[Wodisch]

Hi,

actually it might be more about your shell, than about the signal handler: in the past it was a kind of custom to send kill to pseudo-pid 0 in order to kill all processes of your *session* (ascii-terminal session, remind you).
So the kill command was implemented differently (might have been a "built-in" command, i.e. built-into the shell, like "cd").

FWIW,
Wodisch