Cooler CPU

#!/bin/bash
# Filename: cpulimit-ghb.sh
# Version.: 09032017
# Author..: robz
# I know, I'm cheap, I should buy a better than stock cooling fan, but....
# Dynamically use the cpulimit utility to keep cpu within a sane temperature
# range when using Handbrake or another resource hammering program.
# sudo apt install cpulimit lmsensors - use PPA for the latest Handbrake.
# Dependant on the output of "sensors" you may need to tweak line ##.

if [ "$UID" != "0" ]; then                          # Get root privilege.
    sudo -k; exec gksudo --message "$(echo\
    'Enter your password please, you need root';\
    echo 'privileges to run cpulimit effectively.')"\
    "$0"
fi

max='67'                                            # Maximum temperature°C.
cores='2'                                           # Number of cpu cores.
prog='/usr/bin/ghb'                                 # Program you're limiting.
limit=$((100*cores))                                # Total 100% limit range.
base="$limit"

while [[ "$(pidof "$prog")" ]]; do
    temp=$(sensors | grep 'CPU:' | cut -c18-19)     ## Get cpu temperature.
    if [[ "$temp" -gt "$max" && "$limit" -gt '25' ]]; then
        killall /usr/bin/cpulimit                   # Kill old process.
        ((limit-=25))                               # Increment limit down.
        cpulimit -qb -P "$prog" -l "$limit"         # Start new process.
    elif [[ "$temp" -lt "$max" && "$limit" -lt "$base" ]]; then
        killall /usr/bin/cpulimit
        ((limit+=25))                               # Increment limit up.
        cpulimit -qb -P "$prog" -l "$limit"
    fi
    sleep 5
done

killall /usr/bin/cpulimit
exit