remove_duplicate_entries_in_csv.rb

require 'csv'


def remove_dupes
  uniq_csv = []
  CSV.foreach("input.csv","r+") {|csv| uniq_csv << csv }
  uniq_csv.uniq!.compact.compact
end

CSV.open("ouput.csv","w+") do |csv|
  remove_dupes.each { |entry| csv << entry }
end

If the source CSV isn't too large, could you have just done:

def remote_dupes
   CSV.read("input.csv").uniq
end

(I don't know your data so the #compact and perhaps the double #compact is required)

Also, there is no reason to use the self modifying version "uniq!" where I think you more mean the returning version of "uniq"