reverse_vowels.rb

#!/usr/bin/env ruby

# $ ./reverse_vowels.rb 'lalelilolul'
# lulolilelal
# $ ./reverse_vowels.rb 'lalelilolu'
# lulolilela

VOWELS = 'aeiouy'
string = ARGV[0]

consonants, vowels = string.scan(/([^#{VOWELS}]+)([#{VOWELS}]+)?/i).transpose
vowels.unshift(vowels.pop) if vowels.last.nil?
puts consonants.zip(vowels.reverse).flatten.join

test_vowels.sh

for s in                 \
  lalelilolulyl          \
  laleliloluly           \
  lalelilolul            \
  lalelilolu             \
  laaleeliilooluul       \
  laaleeliilooluu        \
  llallellillollull      \
  llallellillollu        \
  llaalleelliilloolluull \
  llaalleelliilloolluu
do
  ruby reverse_vowels.rb $s
done