Re: -1 pid on sys.wait4?

[Nicholas Murphy <halcyonic at gmail dot com>]

So, yes, dumb question. :)  (sorry...confused myself between $pid and pid())

Thanks,
Nick

On Nov 9, 2012, at 2:59 PM, Josh Stone <jistone@redhat.com> wrote:

> On 11/09/2012 11:53 AM, Nicholas Murphy wrote:
>> Maybe a dumb question, but: why would $pid show up as -1 fairly
>> consistently in a "probe kernel.function("sys_wait4").call" probe?
> 
> Check out "man 2 wait", which says:
> 
>  The value of pid can be:
> 
>  < -1   meaning  wait for any child process whose process group ID is
>         equal to the absolute value of pid.
> 
>  -1     meaning wait for any child process.
> 
>  0      meaning wait for any child process whose process group ID is
>         equal to that of the calling process.
> 
>> 0    meaning wait for the child whose process ID is equal to the
>         value of pid.
> 
> 
> So it just means that the sys_wait4 caller was not specific about which
> child process they're waiting for.