first_perf_script

#!/bin/bash
#This script measures CPU temps and clock every second

# exits the script when any command fails
set -e

# if the scripts catches a "USR1" signal, or an interruption signal, it will exit itself
trap "exit" USR1 SIGHUP SIGINT SIGTERM

# specifying all excutables' paths for newly installed packages and some file names
readonly RM=/bin/rm
readonly SUDO=/usr/bin/sudo
readonly VCGENCMD=/usr/bin/vcgencmd
readonly AWK=/usr/bin/awk
readonly EGREP=/bin/egrep
readonly CUT=/usr/bin/cut
readonly SLEEP=/bin/sleep
readonly FILENAME=kernel_performance_data

# deletes the previous data files in case it exists to avoid conflict
$SUDO $RM -rf $FILENAME

# prints the header to the data file, with a tab delimitor
$AWK -v OFS='\t' 'BEGIN { printf "%s\t%s\t%s\n", "Second elapsed", "Temperature(degrees C)", "CPU Clock(Mhz)" }'  >>$FILENAME

# the second variable
second=0

while true #creates an infinite loop until the script exits itself
do 
    # gets cpu temp and clock using vcgencmd, and uses egrep and cut to get its numeric value
    temp=$($SUDO $VCGENCMD measure_temp | $EGREP -o '[0-9]*\.[0-9]*') 
    cpu_clock=$($SUDO $VCGENCMD measure_clock arm | $CUT -d '=' -f 2-) 

    # prints the tab-delimited data to the file
    $AWK -v OFS='\t' -v second="$second" -v temp="$temp" -v cpu_clock="$((cpu_clock/1000000))" 'BEGIN { printf "%s\t%s\t%s\n", second, temp, cpu_clock }'  >>$FILENAME
    
    # increments the second by 1
    second=$((second + 1))

    # puts the process to sleep for 1 second
    $SLEEP 1
done