clear

select a in \
  'a list of users with the UID greater than 999' \
  'the Day, Month, and Year' \
  'show a file name from lower case to upper case'
do

  case "$REPLY" in
    1) awk -F: '$3>=999' /etc/passwd ;;
    2) date +'Today is %d %B %Y' ;;
    3)
      echo 'What file would you like to change from lower case to uppercase?'
      select y in *; do
        clear
        tr '[:lower:]' '[:upper:]' < "$y"
        break
      done
    ;;
    *) echo 'Invalid input'
  esac

done