Ruby: Remove blank lines and leading ^M characters

remove_blank_line.rb

#!/usr/bin/env ruby
#
# Wubin Qu <quwubin@gmail.com>
#

if ARGV.size != 1
  $stderr.puts "
  Remove blank lines and leading ^M characters

  Usage:

  #{$0} file_name

  Author: Wubin Qu <quwubin@gmail.com>
  "
  exit
end

File.open(ARGV[0]).each_line do |line|
  # Remove ^M when copy files from Windows
  line.gsub!(/\r\n?/, "\n")
  # Remove blank line
  line.sub!(/^\n/, "")
  next if line.size == 0
  $stdout.puts line
end