[TriLUG] kill signals

[Jon Carnes]

First of all, what kill does with a signal is somewhat dependent on the
programming of the process or daemon.  In general though I have found these
three to be used in this manner:
  kill -1 (thats a one) tell the process to re-read its config file or to
re-initialize the process
  kill -6  tells the process to finish up it current process, flush its
buffers and then stop
  kill -9  tells the process to die, die, die immediately.

I was raised to do a kill -1 on process after I had changed its config file.
INETD is a good example of that.  Inetd only reads the config file on
start-up, so if you modify it, instead of stopping and restarting it, you
send it a "kill -1" which tells it to re-load its config into memory.  The
same is true for Named.

I believe that "kill -6" is the default signal, so when you "kill" a process
you are actually sending it signal #6 (SIGABRT - signal to abort).

Normally "kill -6" works great, but sometimes the errant process stops
listening for signals.. whats a sysadmin to do? that's when its time to
bring on the heavy guns: "kill -9"... because we all know that rebooting is
only for Windows!

As I recall, there was great message detailing signal use that passed
through this list about 2 years ago...  It would be in the old archives on
sunsite - not that google cant provide adequate fruit to quench the hunger
of our questions.

Jon
----- Original Message -----
From: "Chris Knowles" <knowlesc at telocity.com>
To: <trilug at trilug.org>
Sent: Thursday, February 14, 2002 8:26 AM
Subject: [TriLUG] kill signals


> OK, I knew -KILL, and thanks to Jon Carnes I'm now familiar with -HUP,
(which
> worked to kill the ppp side of the pptpd gracefully.  Thanks)
>
> I do a kill -l  (That's an L) and I see all these other signals.
>
> How can I find out what they mean?
>
> CJK
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