Test command

Shell Programming and Scripting
1

hello,
i'v trying to use the TEST command and i have some problems with it.
i am trying kill all proccess wich is greater than 25.
i started with - ps -f | grep -v TTY | awk '{print $4}'
but i dont know how to proceed from here..
10x a lot, Daniel.

2

Do you mean process ID's greater than 25 that started from a specific terminal?

cheers,
Devaraj Takhellambam

3

You try the following script.In that,I used ps ajx -U $USER which will list all the processes which are owned by the user.

for x in `ps ajx -U $USER |  grep -v "PID" | awk '{print $2}'`
do
if [[ $x -gt 25 ]]; then
echo "Process Id:$x"
kill -9 $x
fi
done
4

i just want to kill processes that takes more than 25% from the cpu without a script, in 1 command

5

So do u mean that from the top command's output which will list the process about their %CPU occupied level. In that you want to kill that process. Am I correct? Not the process Id greater than 25?

6 
ps -eo "cpu : %C  pid :%p"

this command can give the process id and cpu usage ,
extraction from top command would be a toughest task , since it prints
some terminal related characters

7

The syntax for "ps" varies, as does the output. Please post which Operating System you have.

Btw. When you have multiple CPUs the percentage from "ps" is a percentage of one CPU. Thus a single process could run at 100% CPU without having any adverse effect. The more CPUs you fit to the computer the more likely you are to see processes with a very high CPU percentage.

Detecting a looping process is a fine art and I don't think that a single snapshot of the CPU percentage is useful for deciding whether to kill a process. It is unlikely that you would come up with a single command line which would be safe to run in a commerical environment.

A perfectly sized and perfectly tuned computer would have everything running at 100% with no wait states.

8

exactly.. but i think it would be better to do it with ps

9

Loking more closely at your original post and guessing the version of "ps", I think you will find that column 4 of "ps -f" with heading "C" is not true CPU percentage. It is however a figure related to CPU usage and used for scheduling.

When the figure is rising towards 255, unix lowers the priority of the task to stop it hogging a CPU. The number in the "C" column then goes down until the machine is less busy whence unix then ups the priority again.

10

so.. is there any command that i can kill processes with, that are using more tan 25% of the CPU?

11 
ps -efopid,pcpu |
while read pid cpu
do
  [ ${cpu%.*} -gt 25 ] && kill "$pid"
done
12

@dadiT
Please post which Operating System you have and the number of CPUs on you server.

Unless this is coursework it is not sensible to kill a process just because it has a high %cu usage.