On 20 Feb, 15:53, Chris S wrote:
> Hi,
>
> anyone seen this and have any ideas?
>
> I have created a script called /tmp/chris_script that looks like this
>
> #!/bin/ksh
>
> RET=`ps -ef | grep root | grep chris_script | grep -v grep`
> echo $RET
>
> When I run the script on a P5 box the RET string finds two processes
> (it should only find one - me runnig the script in the first place).
> The second is a child of the first and the first is a child of my
> shell
>
> If I run the script in an infinite while loop
>
> while :
> do
> /tmp/chris_script
> done
>
> then it finds anything from 1 to 5 processes
>
> If I run the script on a P4 box with the same version of AIX it only
> ever finds one process.
>
> Any ideas?

Remember that you will generate five separate processes when you run
you script:

chris_script
ps -ef
grep root
grep chris_script
grep -v grep

But you don't get them straight away - first a fork() creates a copy
of the original process image, then the exce() replaces that image -
so it looks like the POWER5 server is so fast that this process is
becoming visible to you.

>
> If I run the script on a P4 box with the same version of AIX it only
> ever finds one process.
>
> Any ideas?

You could always try simplifying it by cutting down on the number of
spawned processes by using only one grep like:

RET=$(ps -ef | grep -E "[r]oot.*chris_script")

Which should return the exact same result, the [r] part will eliminate
the grep process itself from being displayed.

regards,
Jesper James