Rudimentary script to convert my qmail/vpopmail mail forwarding rules to exim

qmail-to-exim.rb

#!/usr/bin/env ruby

def addr(file)
  if (file =~ /.qmail-default/)
    address = "*"
  elsif (file =~ /.qmail-(.+)/)
    address = $1
  end

  address
end

def dest(rules)
  dest_addr = nil

  if (rules.lines.count == 1)
    if (rules =~ /\| .+vdelivermail '' ([A-Z0-9+_.-]+@[A-Z0-9.-]+)/i)
      dest_addr = $1
    elsif (rules =~ /^([A-Z0-9+_.-]+@[A-Z0-9.-]+)$/i)
      dest_addr = $1
    elsif (rules =~ /^&([A-Z0-9+_.-]+@[A-Z0-9.-]+)$/i)
      dest_addr = $1
    elsif (rules =~ /\| .+vdelivermail '' delete/i)
      dest_addr = ":blackhole:"
    elsif (rules.strip == "#")
      dest_addr = ":blackhole:"
    end
  end

  dest_addr
end

if ARGV.size != 1
  puts("Usage: qmail-to-exim <qmail dir>")
  exit
end

path = ARGV[0]

$stderr.puts("Reading files from #{path}")

Dir.glob("#{path}/.qmail-*").each do |file|

  name = addr(file)

  rules = File.read(file)
  dest_addr = dest(rules)
  if (dest_addr)
    exim_rule = "#{name}: #{dest_addr}"
    puts exim_rule
  else
    $stderr.puts("Unable to parse address from #{file}")
  end

end