Capistrano recipe to move and replace the secret-token on deployment if missing in shared directory

symlink_secret.rb

namespace :deploy do
  desc "Moves and replaces the secret-token if missing in shared directory"
  task :symlink_secret, :roles => :app, :except => { :no_release => true } do 
    filename       = 'secret_token.rb'
    release_secret = "#{release_path}/config/initializers/#{filename}"
    shared_secret  = "#{shared_path}/config/#{filename}"
    
    if capture("[ -f #{shared_secret} ] || echo missing").start_with?('missing')
      rake_command "secret:replace"
      run "mv #{release_secret} #{shared_secret}"
    end
    
    # symlink secret token
    run "ln -nfs #{shared_secret} #{release_secret}"
  end
end

What is rake_command?