class Chef::Knife::Ssh

def tmux
  ssh_dest = lambda do |server|
    identity = "-i #{config[:ssh_identity_file]} " if config[:ssh_identity_file]
    prefix = server.user ? "#{server.user}@" : ""
    "'ssh #{identity}#{prefix}#{server.host}'"
  end
  new_window_cmds = lambda do
    if session.servers_for.size > 1
      [""] + session.servers_for[1..].map do |server|
        if config[:tmux_split]
          "split-window #{ssh_dest.call(server)}; tmux select-layout tiled"
        else
          "new-window -a -n '#{server.host}' #{ssh_dest.call(server)}"
        end
      end
    else
      []
    end.join(" \\; ")
  end
  tmux_name = "'knife ssh #{@name_args[0].tr(":.", "=-")}'"
  begin
    server = session.servers_for.first
    cmd = ["tmux new-session -d -s #{tmux_name}",
           "-n '#{server.host}'", ssh_dest.call(server),
           new_window_cmds.call].join(" ")
    shell_out!(cmd)
    exec("tmux attach-session -t #{tmux_name}")
  rescue Chef::Exceptions::Exec
  end
end