On 02/22/2016 10:50 AM, Ranjan Maitra wrote:
On Mon, 22 Feb 2016 10:38:30 -0800 Rick Stevens <ri...@alldigital.com> wrote:

On 02/22/2016 10:19 AM, Ranjan Maitra wrote:
Hi,

I am running a fully updated F23 box but this question does not have much to do 
with Fedora itself, hence the designator and the disclaimer.

I am wanting to run a script which will look at all the jobs that are running 
and renice all of them which have been on for more than five minutes. (Then I 
can run the script as a cron job as root and be done with automating the 
process.)

Are there any suggestions as to how to go about this task efficiently? 
Actually, before I reinvent the wheel, are there any standard options that 
already exist and which would be more suitable for me than just to do 
everything from scratch.

Use the "-o pid,etimes=" options of ps to get the elapsed time of
tasks in seconds. To get a full list, for example, as root:

        ps ax -o pid,uid,etimes=
        ...
        21412     0     833
        21499     0  631433
        21541     0     773
        21597  1000     769
        21604  1000     769
        21605  1000     769
        21608  1000     769
        21610  1000     769
        21613  1000     769
        21681  1000     769
        21686  1000     769
        21697  1000     769
        21751  1000     742
        ...

(run it as root so you can see ALL of the processes)

As you can see, you get three columns: the first is the PID of the
task, the second is the EUID of the user running it, and the third is
the elapsed time.

So, pull that data into a shell array, look for stuff that has the
second column equal to the user ID you're interested in and the third
column >= 300 seconds and renice the PID in the first column. Note that
I'd avoid renicing any tasks with UIDs < your lowest normal user ID
(typically 100) to keep from starving system tasks.

Hope that helps!

Yes, this absolutely helps, thanks!! But is there a 2-d array in bash (or do we 
do array of arrays)? (I am presuming that I need to store this in a 2-d array 
and then look at columns 2 and 3  and renice the PIDs in column 1.) Also, how 
does one assign the output of the ps to a 2-d array?

Uhm, no. You can simulate them using associative arrays, but it gets
rather hairy. You may want to try something like awk or PHP or Perl to
do this more easily.

----------------------------------------------------------------------
- Rick Stevens, Systems Engineer, AllDigital    ri...@alldigital.com -
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-  Memory is the second thing to go, but I can't remember the first! -
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