Unix Shell Programming Example for B.Sc, B.Tech, BCA, MCA

 8.Print twin prime numbers within a range.

PROGRAM:

echo "enter a range:"

read a

read b

n=$a

while [ $n -le $b ]

do

    c=0

    d=1

    while [ $d -le $n ]

    do

        if [ `expr $n \% $d` -eq 0 ]

        then

            c=`expr $c + 1`

        fi

        d=`expr $d + 1`

    done

    if [ $c -eq 2 ]

    then

        f=$n

        e=`expr $n + 2`

        m=$e

        c=0

        d=1

        while [ $d -le $m ]

        do

            if [ `expr $m \% $d` -eq 0 ]

            then

                c=`expr $c + 1`

            fi

            d=`expr $d + 1`

        done

        if [ $c -eq 2 ]

        then

            echo "twin prime pair=$f,$e"

        fi

       

    fi

n=`expr $n + 1`

done

OUTPUT:

enter a range:

2

10

twin prime pair=3,5

twin prime pair=5,7

[bgc@localhost ~]$ sh 9.sh

enter a range:

3

100

twin prime pair=3,5

twin prime pair=5,7

twin prime pair=11,13

twin prime pair=17,19

twin prime pair=29,31

twin prime pair=41,43

twin prime pair=59,61

twin prime pair=71,73

[bgc@localhost ~]$