Shell Script - Kill Process if CPU usage gets to high for a given time

script.sh

#!/bin/bash

    # ----------------------------------------------------------
    # Author: Griep Marco, www.marcogriep.de
    # License:
    # You can edit, distribute or sell this snippet if you want,
    # but please contribute to my webpage www.marcogriep.com
    #
    # If you use this Script commercially, please send a dollar
    # to "[email protected]" via paypal. (Pay-What-You-Want)
    # ----------------------------------------------------------

    # ----------------------
    # Ajust for your needs :)
    # ----------------------
    _PROCESS_NAME=firefox         #could be kd001 or something like this
    _CPU_THRESHOLD=0.5          #Threshold in GhZ -> 0.2 = 500 mhz -> Will be killed after its still to high after x minutes
    _CPU_THRESHOLD_CRIT=0.7          #Threshold in GhZ -> 0.7 = 700 mhz -> Will be killed immediatly
    _MAX_WAIT=4             #Iterations. Check how often the CPU is to high. Bsp: A Value of 4 Needs 4 Rounds a 1 minute. 4 Minutes + First run = 5 Minutes. After 5 Minutes CPU is still to high, process will be killed

    # -----------------
    # DO NOT EDIT!
    # Instance Variables
    # -----------------
    _CPU_LOAD=0
    _PID=-1
    _CPU_HIGH_FOR=0

    #Endless Loop
    while [ true ]
    do
      #Search Process
      myProcesses=$(ps ax -o pid,pcpu,command | grep $_PROCESS_NAME)
      processList=$(echo $myProcesses | tr " " "\n")

      counter=1;
      for p in $processList
      do
        #Find Process ID
        if [ $counter -eq 1 ] ; then
           _PID=[$p]
          stringLengh=${#_PID}
          stringLengh=$((stringLengh-1));
          _PID=$(echo $_PID | cut -c 2-$stringLengh) 
        fi

        #Find CPU Load of current Process
        if [ $counter -eq 2 ] ; then
           _CPU_LOAD=[$p]
          stringLengh=${#_CPU_LOAD}
          stringLengh=$((stringLengh-1));
          _CPU_LOAD=$(echo $_CPU_LOAD | cut -c 2-$stringLengh)
           break; #if everything found, stop iteration
        fi

        counter=$((counter+1));
      done

      #Check if CPU Load of Process is more than Critical Threshold
      if [ $(bc <<< "$_CPU_LOAD >= $_CPU_THRESHOLD_CRIT") -eq 1 ]; then
        echo "CRITICAL-KILL: CPU usage is over critical threshold. Instant killing process...$_PID by CPU $_CPU_LOAD";
        kill -9 $_PID;
        $_PID=-1;
      else

        #If CPU Use is not Critical but to high.
         if [ $(bc <<< "$_CPU_LOAD >= $_CPU_THRESHOLD") -eq 1 ]; then
          echo "INFO: Found PID greater than Threshold...$_PID by CPU $_CPU_LOAD";

          #Check if after x Minutes, Process is still to high
          if [ $(bc <<< "$_CPU_HIGH_FOR >= $_MAX_WAIT") -eq 1 ]; then
            kill -9 $_PID
            $_PID=-1;
            _CPU_HIGH_FOR=0;
            echo "KILL: PID has to much CPU usage even after timeout. Killing PID... $_PID by CPU $_CPU_LOAD";
          else
            _CPU_HIGH_FOR=$((_CPU_HIGH_FOR+1));
            echo "WARNING: CPU is over threshold, waiting until timeout reached...$_PID by CPU $_CPU_LOAD";
          fi

        else
           echo "INFO: Process is not over Threshold....succeed checking runtime...$_PID by CPU $_CPU_LOAD";
        fi
      fi

      #Wait a minute after next run
      sleep 1m
    done