script to provide some kernel purging routines for ubuntu/debian. this is a first pass at a maintenance script.

purge_old_kernels.rb

#!/usr/bin/env ruby
# 130306, nate
# automate purging old kernels from /boot and updating/upgrading

require 'optparse'

def get_installed_kernels
  installed = %x(/usr/bin/dpkg --get-selections).split("\n").map! {|e| e.sub!(/\t+install/,"")}
  kernels = installed.select {|pkg| pkg =~ %r[linux-image]}
end

def purge_old_kernels(kernels,cutoff)
    kernels.sort![1..-2]
    #kernels.pop
    kernels[1..-cutoff].each do |kernel|
      puts "uninstalling #{kernel}...\n\n"
      %x(/usr/bin/dpkg --purge #{kernel})
  end
end


def apt_fix_broken
  %x(/usr/bin/apt-get -yf install)
end

def apt_autoremove
  %x(/usr/bin/apt-get -y autoremove)
end

def apt_update_upgrade
  %x(/usr/bin/apt-get -y update && /usr/bin/apt-get -y upgrade)
end


options = {}

optparse = OptionParser.new do |opts|

opts.on( '-h', '--help', 'Display this screen' ) do
  opts.separator  ""
  opts.separator "Order should be: #{$0} -k VERSION -faU"
  opts.separator  ""
  puts opts
  exit
end

opts.on( '-A', '--all', "Perform all operations in sequence" ) do
  options[:kernels] = 4
    purge_old_kernels(get_installed_kernels,options[:kernels])
    apt_fix_broken
    apt_autoremove
    apt_update_upgrade
end


opts.on( '-a', '--autoremove', "Run apt-get autoremove" ) do
  options[:simple] = true
  apt_autoremove
end

opts.on( '-f', '--fix-broken', "Run apt-get -f install" ) do
  options[:simple] = true
  apt_fix_broken
end

options[:opt] = false 
opts.on( '-k', '--kernel [KERNELS_TO_KEEP]', Integer, "List the number of kernels to keep. Example: -k 4" ) do |k|
  options[:opt] = k || 4
    purge_old_kernels(get_installed_kernels,options[:opt])
end

opts.on( '-l', '--list-kernels', "Lists currently installed kernels" ) do
  options[:simple] = true
  get_installed_kernels.each {|k| puts k}
end

opts.on( '-n', '--noop', "Just show passed options and quit" ) do
  options[:simple] = true
  p options
  exit
end

opts.on( '-U', '--update-upgrade', "Run apt-get update && apt-get upgrade" ) do
  options[:simple] = true
  puts "upgrading now..."
  apt_update_upgrade
end


# opts.on( '-R', '--reboot', "Reboot this host upon completion of updates" ) do
#   options[:simple] = true
#   puts "rebooting now..."
# end

end

optparse.parse!