kill -9 PID fails. why?

[nigel at cmsfl]

First of I'm not a guru on this but I have picked up a couple of things
along the way ...

In article <8498 at unix.SRI.COM>, ric at ace.sri.com (Richard Steinberger) writes:
> Sometimes I see a user has been logged on several days without doing
> anything.  ps shows that the process is sleeping, waiting for input.

You should try kill -1 PID first.  This is much nicer to the user i.e.
if he/she is in say vi and it gets a -1 signal it will save the edit
session for them.  A -9 will just clobber the process.

> Many times I am unable to kill such a process.  What I have been doing
> is kill -9 PID, where PID is the user's process ID.  Could someone
> shed some light on why such processes don't die.

The ones I have struck which can't be killed I have assumed to be what
are called zombie processes.  Processes whose parent i.e. the shell or
something, have died and they have not for what ever reason.  Perhaps
someone with real knowledge can fill that one in ;-)

> Is there a particular
> document that I might peruse to understand this situation better?  And
> if kill -9 doesn't work, do I have any alternatives other than reboot?

I have had to reboot as well.

> thanks to all who reply.  Apologies if this is frequently dealt with.

Never seen it before in comp.sys.ncr but probably has been beaten to
death in comp.unix.questions etc.

-- 
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