Quick n' dirty utility to compare sysctls between two machines.

compare_sysctl.rb

#!/usr/bin/env ruby

#
# This utility compares `sysctl -a` on two given boxes
#

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

SYSCTLS = {}

def sysctls(hostname)
  raw = `ssh #{hostname} 'sysctl -a'`
  Hash.new.tap do |packages|
    raw.split("\n").each do |line|
      name, value = *line.split('=').collect(&:strip)
      SYSCTLS[name] ||= []
      SYSCTLS[name] << [hostname, value]
    end
  end
end

ARGV.each do |hostname|
  sysctls hostname
end


exclusives = {}
shared     = {}

SYSCTLS.each do |name, record|
  if record.length == 1
    hostname = record.first.first

    exclusives[hostname] ||= []
    exclusives[hostname] << name
  elsif record.length == 2
    first_host_sysctl_value  = record.first.last
    second_host_sysctl_value = record.last.last
    if first_host_sysctl_value != second_host_sysctl_value
      shared[name] = record
    end
  else
    puts "MULTIPLE values for sysctl #{name}, you figure it out: #{record}"
  end
end

exclusives.each do |hostname, sysctls|
  sysctls.each do |sysctl|
    puts "ONLY #{hostname} has sysctl #{sysctl}"
  end
end

shared.each do |name, information|
  first_host_info  = information.first
  second_host_info = information.last

  first_host  = first_host_info.first
  second_host = second_host_info.first

  first_host_sysctl_value  = first_host_info.last
  second_host_sysctl_value = second_host_info.last

  if first_host_sysctl_value != second_host_sysctl_value
    differences = {first_host => first_host_sysctl_value, second_host => second_host_sysctl_value }
    puts "BOTH #{name} #{differences}"
  end

end