Bonus.script

#!/bin/bash 

clear 
echo "
  Please input: 
  #. Three Letter Airport Code
  or
  #. City, State Name
  or
  #. "Quit" to Exit
  " 
invalid_input () { 
  echo "Invalid input '$REPLY'" >&2 
  exit 1 
} 

read -p "Please Input " 
     if [[ "$REPLY" == Quit ]]; then
     echo "Exit."
     exit 
     
     fi
#this is for the three letter code
     if [[ "$REPLY" =~ ^[a-zA-Z]${3} ]]; then 
        echo -e "The number of delayed flights to or from $REPLY is:"
        grep -w "$Reply" /ufrc/zoo6927/share/Class_Files/data/flights.May2017-Apr2018.csv | cut -d "," -f 3,7,13,16,24 | grep GNV | grep 1.00 | wc -l
        
#For city, state name
     elif [[ $REPLY =~ ^[a-zA-Z]\,[a-zA-Z]{2}$ ]]; then
        echo -e "The number of delayed flights to or from $REPLY is:"
        grep -w /ufrc/zoo6927/share/Class_Files/data/flights.May2017-Apr2018.csv | cut -d "," -f 3,7,13,16,24 | grep GNV | grep 1.00 | wc -l
#invalid input
     else
          invalid_input >&2
          exit
     fi