On 02/22/2016 10:50 AM, Ranjan Maitra wrote:
On Mon, 22 Feb 2016 10:38:30 -0800 Rick Stevens <ricks@xxxxxxxxxxxxxx> 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 ricks@xxxxxxxxxxxxxx -
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- -
- Memory is the second thing to go, but I can't remember the first! -
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