Question

Write a script that works in vim:

We are given a Java program RandomTest.java that generates specified number of random integers in the range [0...99]. The program prints FAIL if either 0 or 99 is generated (along with a count of how many times). Otherwise it prints PASS. The program takes the number of random integers to generate as a command line argument as shown below. Note that the given results each time is is run.

[an@localhost ~] java Random Test

Usage: java RandomTest<numRandoms>

[an@localhost ~] java RandomTest 10

PASS

[an@localhost ~] java RandomTest 10

Fail 2

[an@localhost ~] java RandomTest 10

FAIL 1

Write a shell script named tester.sh that compiles RandomTest.java and then runs RandomTest a hundred times, with numRandoms=10 each time, and keeps track of the number of times it passes. (Hint: use a for loop) The output looks like as follows (where the pass rate varies because of random numbers):

[an@localhost ~] ./tester.sh

For numRandoms = 10 pass rate = 79

Modify your shell script such that it runs the tests for numRandoms= 10, 20, 30, and 40. For each number of randoms, it prints out he pass rate (Hint: use a nested for loop). For example, the output may now look like as shown below:

[an@localhost ~] ./tester.sh

For num Randoms = 10 pass rate = 82

For num Randoms = 20 pass rate = 56

For num Randoms = 30 pass rate = 60

For num Randoms = 40 pass rate = 42

Answer 1

This seems to be a very interesting Integration problem where you need to invoke your java program through a shell script.

PART ONE: JAVA PROGRAM

Consider the following java program to understand the basic working of how to generate random numbers in java:

******************************START OF PROGRAM*********************************

import java.util.*;
class RandomTest{
public static void main(String[] args) {
int count_0_99=0; //Counter to hold count of 0 and 99
Random rnum = new Random();
for (int counter = 0; counter <= Integer.parseInt(args[0]); counter++) {
int a = rnum.nextInt(100);
       if (a==99 || a==0)
           {

count_0_99++; //Incrementing Counter
           }
         
}
  
   if(count_0_99 == 0)
       System.out.println("PASS");
   else
       System.out.println("FAIL " + count_0_99);   
      
}
}

********************END OF JAVA PROGRAM**************************

PART TWO: WRITING A SHELL SCRIPT

Shell scripts are also called as bash scripts. They have extension of .sh or .bash. They are an abbreviation of Bourne-Again Shell.

* Writing a shell script is a very handy tool and it helps us to do numerous operations like searching, storing, printing etc.

* Now we will write a shell script to run the above java program 100 times for generating 10 integers and take actions accordingly.

* Make sure to read comments inside the code at all the important places

**************************BASH SCRIPT*************************************

#!/bin/bash
counter = 0
for i in {1..100}
do
javac RandomTest.java                  #COMPILING JAVA PROGRAM
returnValue = $(java RandomTest 10)    #RUNNING JAVA PROGRAM FOR 10 INTEGERS and STORING ITS OUTPUT            

if [[ $returnValue = *PASS* ]]         #Searching inside the variable to detect "PASS" or "FAIL"
then
    let "counter+=1"                   #PASS COUNTER
fi
done

echo "For numRandoms=10 pass rate=$counter

*************************END OF BASH SCRIPT***********************************

PART THREE: MODIFICATION TO SHELL SCRIPT

This part contains the modification to shell script to run for 10,20,30,40 integers the same test that we carried above.

* The idea here is we are going to use nesting of loops.

* The First loop will iterate from 10,20,30 and 40 whereas the second loop will do the same as above. The only difference is the arguments passed in the above will now change. e.g. For the first iteration, 10 random numbers will be processed, for 2nd iteration 20 random numbers will be processed and so on.

* Please read the comments at all important sections of code.

* HAPPY CODING :)

*************************START*************************

#!/bin/bash

for j in {10..40..10}                      #LOOP TO ITERATE OVER 10,20,30,40
do
    counter = 0                            #COUNTER FOR HOLDING PASS 
    for i in {1..100}
    do
    javac RandomTest.java                  #COMPILING JAVA PROGRAM
    returnValue = $(java RandomTest $j)    #RUNNING JAVA PROGRAM and STORING ITS OUTPUT IN A VARIABLE
    if [[ $returnValue = *PASS* ]]         #Searching inside the variable to detect "PASS" or "FAIL"
    then
        let "counter+=1"                   #INCREMENTING PASS COUNTER
    fi
    done
    echo "For numRandoms=$j pass rate=$counter"
done

***************************COMPLETE*******************************

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