Rake - upgrade a Ghost blog installation

ghost-upgrade.rake

require 'bundler'
require 'fileutils'
Bundler.require

GHOST_DIR = ENV['GHOST_HOME'] || '<your_ghost_folder>'
THEME = 'casper'

namespace :blog do

  desc 'Upgrades Ghost using given file'
  task :upgrade, :file do |t, args|
    ghost_archive = args[:file]
    abort 'Please specify a .zip package' unless File.extname(ghost_archive) == '.zip'
    Dir.chdir GHOST_DIR
    `tar cvzf content-backup.tgz content` # backup content files
    FileUtils.rm_rf 'core'
    Dir.mkdir 'tmp' unless Dir.exist? 'tmp'
    Dir.chdir 'tmp' do
      `unzip #{ghost_archive}`
      files = Dir.glob '*'
      FileUtils.cp_r files, GHOST_DIR, remove_destination: true
    end
    FileUtils.rm_rf 'tmp'
    `npm install --production`
    puts "Successfully upgraded to ghost version #{/((\d)+\.)+/.match(ghost_archive)[0].chop}!"
  end

end

Check out my informative blog post on this script