Get latest revision that deployed.

latest_revision.rb

# put this snippet to config/deploy.rb
# then call via Capistrano Rake task
# bundle exec cap staging latest_revision

desc "View latest commit that deploy on server"
task :latest_revision, :roles => :app do
  trap("INT") { puts 'Interupted'; exit 0; }
  run "cat #{deploy_to}/current/REVISION" do |channel, stream, data|
    puts  
    puts "******* REVISION ********"
    puts "Server   : #{channel[:host]}"
    puts "Revision : #{data}"
    puts "*************************"
    puts 
    break if stream == :err
  end
end