Quick n' dirty utility to compare the state of packages on two ubuntu/debian machines.

compare_dpkg.rb

#!/usr/bin/env ruby

#
# This utility compares the state of `dpkg -l` on two given boxes
#

puts "Usage: #{$PROGRAM_NAME} hostname other_hostname" and exit unless ARGV.length == 2

PACKAGES = {}

def dpkg(hostname)
  raw = `ssh #{hostname} 'dpkg -l | egrep "^[a-z]{2} " | sed -r "s/ +/ /g" | cut -f 1,2,3,4 -d " "'`
  Hash.new.tap do |packages|
    raw.split("\n").each do |line|
      status, name, version, arch = *line.split(' ')
      name.gsub!(/:.*/, '')
      PACKAGES[name] ||= []
      PACKAGES[name] << [hostname, {
        status: status,
        version: version,
        arch: arch
      }]
    end
  end
end

ARGV.each do |hostname|
  dpkg hostname
end

exclusives = {}
shared     = {}

PACKAGES.each do |package, record|
  if record.length == 1
    hostname = record.first.first

    exclusives[hostname] ||= []
    exclusives[hostname] << package
  else
    first_host_package_info  = record.first.last
    second_host_package_info = record.last.last
    if first_host_package_info != second_host_package_info
      shared[package] = record
    end
  end
end


exclusives.each do |hostname, packages|
  packages.each do |package|
    puts "ONLY #{hostname} has package #{package}"
  end
end

shared.each do |package, installation_information|
  first_host_info  = installation_information.first
  second_host_info = installation_information.last

  first_host  = first_host_info.first
  second_host = second_host_info.first

  first_host_package_info  = first_host_info.last
  second_host_package_info = second_host_info.last

  differences = {}
  first_host_package_info.collect do |k, v|
    if v != second_host_package_info[k]
      differences[k] = {first_host => v, second_host => second_host_package_info[k] }
    end
  end

  puts "BOTH #{package} #{differences}"
end