def sh (command, as: user, on: hosts, quiet: false, once: nil)
      self.once once, quiet: quiet do
        log.info "sh #{command}", quiet: quiet do
          hash_map(hosts) do |host|
            host.sh command, as: as, quiet: quiet
          end
        end
      end
    end
def sh (command, as: user, on: hosts, quiet: false, once: nil)
      self.once once, quiet: quiet do
        log.info "sh #{command}", quiet: quiet do
          hash_map(hosts) do |host|
            host.sh command, as: as, quiet: quiet
          end
        end
      end
    end
Execute a shell command on each host
 @macro onable
 @macro asable
 @macro quietable
 @macro onceable