Re: [PATCH 2/2] ulogd: Implement PID file writing

[Chris Boot <bootc@bootc.net>]

On 11/05/2013 20:21, Pablo Neira Ayuso wrote:
> Hi Chris,
>
> On Sat, May 11, 2013 at 06:01:53PM +0100, Chris Boot wrote:
>> The deamon currently does not have the ability to write a PID file to track its
>> process ID. This is very useful to an init script and to ensure there is only
>> one running instance. This patch implements this functionality.
> This belongs to the scope of the script and it doesn't seem to be
> useful for the internal operation of ulogd2.
>
> You can generate that PID file with something like:
>
> ps -ef | grep ulogd$ | awk '{ printf $2 }'
>
> And someone may want to have more than one instance of ulogd2, that's
> perfectly possible. Actually that's a good idea if you need to log
> both NFLOG and NFCT at the same time and you're running ulogd2 in a
> multi-core system. That will help to avoid hitting Netlink overrun
> errors.

Hi Pablo,

I'd argue exactly the opposite point: that when you want multiple
instances a PID file can help you work out which is which. My patch adds
an option that takes a filename argument, so two instances can write to
two different PID files; grepping ps won't easily tell you which
instance is the correct one (without resorting to grepping for
command-line arguments). Additionally, using a PID file is completely
optional and there is no change in behaviour unless you pass the argument.

Cheers,
Chris

-- 
Chris Boot
bootc@bootc.net