Sort lines, ignoring leading and trailing blank lines

gistfile1.rb

#!/usr/bin/ruby

input = STDIN.read

lead_regex = /\A[\n\s]*\n/
tail_regex = /[\n\s]*\Z/

lead_blank = input[lead_regex]
tail_blank = input[tail_regex]

content = input.sub(lead_regex, "").sub(tail_regex, "")
sorted = content.lines.collect { |l| l.sub(/\n\Z/, "") }.sort.join("\n")
finished = "#{lead_blank}#{sorted}#{tail_blank}"

STDOUT.write finished