# LibTmux::Async::ControlSubscription#next

- **Module:** LibTmux::Async
- **Package:** libtmux-async
- **Language:** Ruby
- **Kind:** method
- **Source:** https://github.com/libtmux/libtmux-ruby/blob/d8ce4bbee0ca7748a81929f81f7d8d07f8c51267/gems/libtmux-async/lib/libtmux/async/control.rb#L20
- **Page:** https://libtmux.org/en/ruby/v0.1.0.alpha.3/reference/libtmux-async-controlsubscription-next/

```
def next: (?timeout: ::Numeric?) -> ::LibTmux::ControlEvent
```

Behavior: Control subscriptions.

Behavior contract: Control subscriptions.

## Examples

Open a control connection inside an Async scope and read the notification tmux sends when a window is renamed. Use Ruby 4.0.7, Bundler, Git and tmux 3.3a or newer on Unix, with /bin/cat and /bin/sh available. In an empty directory, fetch the documented library revision:

```console
$ git clone https://github.com/libtmux/libtmux-ruby.git libtmux-source && \
  git -C libtmux-source checkout d8ce4bbee0ca7748a81929f81f7d8d07f8c51267
```

Save this dependency file as Gemfile:

```ruby
source "https://rubygems.org"

gem "libtmux-async", path: "libtmux-source/gems/libtmux-async"
```

Save this complete program as async_control.rb. Its Server.start block owns a private tmux server and stops it on exit, including after an error.

[Source example](https://github.com/libtmux/libtmux-ruby/blob/d8ce4bbee0ca7748a81929f81f7d8d07f8c51267/examples/api/async_control.rb).

```ruby
# frozen_string_literal: true

begin
  # docs:begin main
  require "libtmux"
  require "libtmux/async"

  LibTmux::Server.start do |server|
    session = server.new_session(name: "work", command: ["/bin/cat"])
    window = session.list_windows.fetch(0)
    Async do |parent|
      LibTmux::Async.open(parent: parent, server: server) do |scope|
        scope.server.open_control(session: session.ref) do |control|
          reply = control.exchange("display-message -p ready", timeout: 5)
          puts "reply: #{reply.blocks.last.body.strip}"
          events = control.events
          window.rename("renamed")
          event = events.next(timeout: 5) until event&.raw&.start_with?("%window-renamed")
          puts "event: #{event.raw.strip}"
        end
      end
    end.wait
  end
  # docs:end main
rescue StandardError => error
  warn "#{error.class}: #{error.message}"
  exit 1
end
```

Install the runtime dependencies and run the saved program. An operation or cleanup error makes it exit unsuccessfully:

```console
$ bundle config set --local path vendor/bundle && \
  bundle install --jobs 2 && \
  bundle exec ruby async_control.rb
```

Expected output:

```text
reply: ready
event: %window-renamed @0 renamed
```

## Parameters

- `timeout` (`::Numeric?`)