bash-control how many cpu/vm/io to stress

Question

I have created a script to stress the cpu, vm and io of a virtual machine and write the results to a file. I have written the script in such a way that it will read user input for how long in seconds they would like to run each test. However, I have had to hard code the number of cpus etc as 4. How can I change this script so that the user can select how many cpu/vm/io to stress in addition to how long?

The script is as follows:

#!/bin/bash
#
# Script to get stress statistics#

echo "Enter the number of intervals (seconds) for running the stress statistics:"


read seconds_to_run
# the variable "seconds_to_run" now has the value entered by keyboard

# The stress option chosen will be output to the corresponding file and timestamped with today's date.
out_cpufilename="/tmp/stress_cpu_stat_"$( date +"%B.%d" )
out_vmfilename="/tmp/stress_vm_stat_"$( date +"%B.%d" )
out_iofilename="/tmp/stress_io_stat_"$( date +"%B.%d" )


while true; do
    clear
    echo "*******************************"
    echo "* Choose from the following: *"
    echo "*******************************"
    echo "* [1] To stress cpu statistics *"
    echo "* [2] To view stress vm statistics *"
    echo "* [3] To view stress io statistics *"
    echo "Press A to quit."
    echo "************************"
    echo -n "Enter your menu choice [1-3]: "

    read choice


    case  $choice in    
        1) echo "stress cpu statistics"
            stress -c 4 -t $choice |tee $out_cpufilename 
            echo "This file will be saved to $out_cpufilename"
            sleep 3 ;;

        2) echo "stress cpu statistics"
            stress -m 4 -t $choice |tee $out_vmfilename 
            echo "This file will be saved to $out_vmfilename"
            sleep 3 ;;

        3) echo "stress cpu statistics"
            stress -i 4 -t $choice |tee $out_iofilename 
            echo "This file will be saved to $out_iofilename"
            sleep 3 ;;


        A) #Quit option
            echo You have chosen to quit.
            exit;;   

        *) #Wildcard option in case user enters an invalid option such as "e"
            echo Invalid choice, please make another choice
            sleep 3;;


    esac
done

Answer 1

grep -c ^processor /proc/cpuinfo

Will give you the number cores that the machine has

Answer 2

You just need to read the number of cores into a variable:

echo -n "Number of cores: "
read cores

Add this at the position you find most suitable. To use the variable instead of the hard coded values, replace each occurence of 4 with "$cores".

A small hint in case you choose to turn your back on Java and become a Bash enthusiast: In order to avoid typical problems with spaces and special characters, it is a best practice to always enclose bash variables in quotes ("$cores") or curly braces (${cores}).