write Shell script to show menu options and perform actions

#!/bin/bash
################################################################################
# Name: sy_3
#
# Menu options.
#
# Usage: sy_3
#
# Author: Suresh Yadagiri
# Date: 2010/07/20
# Write a Bourne Shell Script that displays the following menu and
# primpts you for one-character input to invoke a menu options as fillows
#   
#   a. list all files in the present working directory
#   b. display today's date and time
#   c. Invoke shell script for problem 14
#   d. display whethe a file is simple file or a directory
#   e. create a backup for a file
#   f. start a telnet session
#   g. start an ftp session
#
#   c. requires that you ask for a list of login names
#   Problem 14:   write a Bourne shell script that takes a list of
#   login names as its arguments and display the number of terminals
#   that each user is logged on to in a LAN environment
#     
#   d.insert a prompt for file names before invoking a shell command/program
#      
#   e.insert a prompt for file names before invoking a shell command/program
#       
#   f.insert a prompt for a domain name or IP address before initiating telnet
#   or frp session
#   Quit only one option x entered
#
#     Usage: ./sy_3
##################################################################################

function verifyfile(){
filename=$1
if [ -d $filename ]
then
echo "$filename  is a directory"
return
fi

if [ ! -f $filename ]
then
echo "\"$filename\" File or Directory not exists"
else
    echo "$filename is ordinary file"
fi
   
}

#
#
#

function createbackup(){

    filename=$1
    if [ -d $filename ]
    then
        echo "$filename  is a directory.enter file name"
        return
    fi

    if [ ! -f $filename ]
    then
        echo "File is not exists"
    fi

    backupfilename=${filename}_backup
    #echo "backup file name is $backupfilename"
    cp -f "$filename" $backupfilename >/dev/null 2>>/dev/null
    if [ $? -eq 0 ]
    then
    echo "Backup created and file name is $backupfilename"
    else
    echo "Backup creation failed"
    fi   

}

function handleftp(){
ftp $1 < /dev/tty
}


function handletelnet(){
telnet $1
}

while true
do
clear
echo "Use One of the following options:"

echo "    a|A:    List all files in the present working directory"
echo "    b|B:    Display today's date and time"
echo "    c|C:    Invoke shell script [display no.of terminal logged on]"
echo "    d|D:    Display whether a file is a simple file or direcotry"
echo "    e|E:    create a backup for a file"
echo "    f|F:    start the telnet session"
echo "    g|G:    start an ftp session"
echo "    x|X:    Exit"

echo -e "Enter your option and hit : \c"

read option

case "$option" in
    a|A)
         ls;   
        ;;
    b|B)   
        echo "Today date and time is `date`"   
        ;;
    c|C)
        echo "Enter login names separated by space: "   
        read loginnames
            ./sy_page1_14 $loginnames
        ;;
    d|D)   
          echo -e "Enter a file name to check its type: \c"   
        read filename
        verifyfile $filename
        ;;
    e|E)
          echo -e "Enter a file name for backup: \c"   
        read filename
        createbackup $filename
        ;;
    f|F)
        #echo "you entered f"
        echo -e "Enter IP address/domain name for telnet session: \c"
        read ipaddress
        handletelnet $ipaddress
        ;;
    g|G)
        #echo "you entered g"
        echo -e "Enter IP address/domain name for ftp session: \c"
        read ipaddress
        handleftp $ipaddress
        ;;
    x|X)
        echo "Thank you ....Bye"
        break;
        exit 0;
        ;;
    *)
        echo "Invalid Option; try again"
        ;;
esac
echo -e "Press [enter] key to continue. . .\c";
read presskey
done
exit 0