#!/usr/bin/env ruby
#--
#    Name    : vm_mac_fixer
#    Author  : Jerod Santo
#    Contact : "moc.liamg@otnas.dorej".reverse
#    Date    : 2008 September 15
#    About   : Debian-based vmware virtual machines lose their eth0 after being copied to a new
#              host. This script will check to see if a machine has lost its eth0, fix it, and reboot
#--

if_status = `ifconfig eth0 2>&1` # 2>&1 redirects stderr to stdout so we can capture it
config_file = "/etc/udev/rules.d/z25_persistent-net.rules"

if if_status =~ /Device not found/
  config_text = Array.new
  File.open(config_file,"r") { |file| config_text = file.readlines }
  relevant_text = config_text.select { |line| line =~ /^SUBSYSTEM==/ }
  output = relevant_text.last.gsub(/eth\d/,"eth0")
  File.open(config_file,"w"){ |file| file.puts output }
  system("reboot")
end