Don't randomize. That way you are going to get the same quotes repeated.

Instead do one of the following:
  • Keep a simple counter in the file and increment it each time a quote is issued. When you run out of quotes reset it to "1". This will give you a new quote each time you run it.
  • Convert the day to an internal number and use "internal_date mod number_of_quotes" to determine which quote to use. This will give you a new quote every day, but if you run the script many times on the same day you will always get the same quote. This has the added bonus that you cam make the quote file read only.