write a c shell script that takes an integer number from the keyboard and displays the fibonacci numbners equal to the number entered from the keyboard. thus if the user enters 7, your script displays the first seven fibonacci numbers

#!/bin/bash
#####################################################
# File Name: sy_4_g
#
# Usage: ./sy_4_g
#
# Author: Suresh Yadagiri
# Date:  August 06,2010
#
# Requirements:
#     write a c shell script that takes an integer number
#     from the keyboard and displays the fibonacci numbners
#     equal to the number entered from the keyboard.
#     thus if the user enters 7, your script displays the
#     first seven fibonacci numbers
#
#
#####################################################

function printusageinfo(){
echo -e "\nUsage: $0 \n"
}

function is_integer() {
    printf "%d" $1 > /dev/null 2>&1
    return $?
}

if [ $# -eq 0 ]
then
        echo "At least one argument expected"
        printusageinfo
        exit 1
fi

if [ $# -gt 1 ]
then
        echo "Too many arguments"
        printusageinfo
        exit 1
fi

if ! is_integer $1;
then
        echo "Integer argument expected"
        printusageinfo
        exit 1
fi

if [ $1 -lt 2 ]
then
        echo "invalid arguments.enter greater value"
        printusageinfo
        exit 1
fi

echo "The first $1 fibonacci numbers are"
counter=2
n1=0
n2=1
echo $n1
echo $n2
until [ $counter -eq $1 ]
do
  current=`expr $n1 + $n2`
  echo $current
  counter=`expr $counter + 1`
  n1=$n2
  n2=$current
done
exit 0