[RUBY CODE]
#!/usr/local/bin/ruby

def file_contents(file)
  File.open(file, 'r') do |f|
    f.each_line do |line|
      return line
    end
  end
end

@hash = {}
def populate_and_sort_hash
  Dir.entries('.').each do |f|
    next if !f.match(/(a|b|c|d|e).txt/)
    @hash[f] = file_contents(f) if !File.directory? f
  end
  puts @hash.sort_by{|k,v| v}
end

populate_and_sort_hash


[OUTPUT]
aguevara@anthony ~/Documents/Bash/Temp $ ruby Test.rb
d.txt
Mar 05 13:00
b.txt
Mar 08 18:00
c.txt
Mar 10 20:00
e.txt
Mar 12 14:00
a.txt
Mar 15 19:15