Question

2

What is wrong with my shell script?

rated 0 times [ 2] [ 0] / answers: 1 / hits: 653 / 1 Year ago, wed, february 1, 2023, 2:58:16

The following program is giving error on line 7 and 9: the while loop does not seem to be working. It is a program to show all the prime and composite numbers from 3 to a desired given input.

echo prograam to find all the prime numbers from 3 to given number

echo enter the last number

read number

n=$number

i=3

m=3

    while [ $m -le $n ]

    do 

        while [ $i -le $m ]

        do  

        m=`expr $n % $i`

        i=`expr $i +1`

            if [ $m -eq 0 ]

            then

            echo $n is a prime number 



            else

            echo $n is not a prime number 



            fi

        done

    m=`expr $m +1`

    done

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answered 1 Year ago antorchestr · Accepted Answer

Re-wrote the shell script for you:

echo "program to find all the prime numbers from 3 to given number"

echo "enter the last number"

read number

n=$number

i=2

m=2

is_prime=0

    while [ "$m" -lt "$n" ]

    do

        while [ "$i" -le "$m" ]

        do

            m=$(expr $n % $i)

            i=$(expr $i + 1)

            if [ "$m" -eq 0 ]

                then

                echo "$n is not a prime number"

                exit

            else

                is_prime=1

            fi

        done

    m=$(expr "$m" + 1)

    done

if [ "$is_prime" -eq 1 ]; then

    echo "$n is a prime number"

fi

exit

Referred to the following for this:

Operators in bash

How to use expr in bash