Write a shell script to Perform Following String Operations

Definition : Write A Script To Perform Following String Operations Using Menu: 

                       1. COMPARE TWO STRINGS.

                       2. JOIN TWO STRINGS.

                       3. FIND THE LENGTH OF A GIVEN STRING.

                       4. OCCURRENCE OF CHARACTER AND WORDS

                       5. REVERSE THE STRING.

File Name : ex18.sh

clear

choice=y

while [ "$choice" = "y" ]

do

echo "____________________________________________"

echo "1. COMPARE TWO STRINGS"

echo "2. JOIN TWO STRINGS"

echo "3. FIND THE LENGTH OF A GIVEN STRING"

echo "4. OCCURRENCE OF CHARACTER AND WORDS"

echo "5. REVERSE THE STRING"

echo "6. EXIT"

echo "____________________________________________"

echo "Enter Choice: \c"

read ch

echo "____________________________________________"

case $ch in

1)

        echo "Enter String1: \c"

        read str1

        echo "Enter String2: \c"

        read str2

        if [ $str1 = $str2 ]

        then

                echo "String is equal"

        else

                echo "String is not equal"

        fi

        ;;

2)

        echo "Enter String1: \c"

        read str1

        echo "Enter String2: \c"

        read str2

        str3=$str1$str2

        echo "Join String: \c" $str3

        ;;

3)

        len=0

        echo "Enter String1: \c"

        read str1

            len=$(echo "$str1" | wc -c)

            len=`expr $len - 1`

        echo "Length: " $len

        ;;

4)

        echo "Enter String: \c"

        read str

        echo "Enter Word to find : \c"

        read word

        echo $str | cat > str1.txt

        grep -o $word str1.txt | cat > str2.txt

        count=`grep -c $word str2.txt`

            echo "Count:  \c"$count

    ;;

5)

        echo "Enter String1: \c"

        read str

        len=`expr $str | wc -c`

        len=`expr $len - 1`

        while [ $len -gt 0 ]

        do

                rev=`expr $str | cut -c $len`

                ans=$ans$rev

                len=`expr $len - 1`

        done

        echo "Reverse String: \c"$ans

        ;;

6)         exit      ;;

*)         echo "Invalid Choice ....."                    ;;

            esac

 echo "Do u want to continue.....? [y/n]"

 read choice

 case $choice in

  Y|y) choice=y;;

  N|n) choice=n;;

  *) choice=y;;

 esac

done