vlanconvert.rb

#!/usr/bin/env ruby

INTEST = '5 10 20 50-60 70-73 75-79 80 95'.freeze
OUTTEST = '5 10 20 50 51 52 53 54 55 56 57 58 59 60 70 71 72 73 75 76 77 78 79 80 95'.freeze

def rangeconvert(r)
  start, finish = r.scan(/\d+/)
  raise "Invalid input" unless start < finish
  (start..finish).to_a.join(' ')
end

def vlanconvert(vlans)
  vlans.gsub(/\d+-\d+/) { |s| rangeconvert(s) }
end

outputtest = vlanconvert(INTEST)
raise "failed" unless outputtest == OUTTEST