#!/bin/bash

# Variable Declarations!
word_count=$(wc -l $3 | cut -d ' ' -f 1)

#Error Checking!
# check if there are exactly 3 arguments given
if [[ "$#" -ne 3 ]]; then
 echo "Error: "$0" needs 3 arguments!"
 echo "usage: "$0" int int file_name"
 exit
elif [[ "$#" -eq 3 ]]; then

 # check if file exists
 if [[ -e "$3" ]]; then

  # check if the first num is less than or equal to the second num
  if [[ "$1" -le "$2" ]]; then

   # check if the number of lines in the file is greater than the last line to be printed
   if [[ $word_count -gt $2 ]]; then
    head -"$1" "$3"| tail -"$2"
   else
    echo "Error! File has less lines than the last line to be printed, print less lines!"
    exit
   fi

  else
   echo "Error! Invalid line paramaters: first argument must be less than the second!"
   exit
  fi

 else
  echo "Error: File does not exist!"
  exit
 fi

fi